What do Adirondack chairs, Stetson hats, the city of Pasadena, and World War I have in common? According to John Green, all of their origin stories include tuberculosis.

In his new book, John argues that it’s impossible to separate the deadliest disease in history from, well, the rest of history. Adirondack chairs were designed by a man who vacationed in the New York mountains—a popular spot for TB patients seeking fresh air—and soon became staples of sanatorium porches across the country. John B. Stetson, who had TB himself, traveled west for dry mountain air and invented the cowboy hat to protect from sun, wind, and rain. Pasadena became a hub for TB treatment in the late 1800s, and TB “tourism” was a major driver of the city’s early economy, real estate, and identity. And the teenage assassins who killed Archduke Franz Ferdinand, which kicked off World War I? They were more willing to die for their cause since they were already dying of TB. 

No wonder John calls this book Everything Is Tuberculosis. In so many ways, TB shaped the world we live in. Even though the disease is now both rare and treatable in rich countries, in poorer places it’s on the rise and still a death sentence for so many.  

John is best known as the author of some of the best young adult novels of all time (at least according to my daughter Phoebe, whose encouragement led me to read The Fault in Our Stars and Turtles All the Way Down). So a lot of people were surprised when he announced that his next book would be about global health—about a disease most people in the western world think of in the past tense.

I wasn’t. After all, I first met John over a decade ago, when he joined me on a Gates Foundation trip to Ethiopia. While traveling, we talked about a lot of the big questions John wrestles with in Everything Is Tuberculosis—like why the place a person is born influences their odds of surviving childhood (or childbirth), and what people like us can do to increase those odds.

Since then, John has been an invaluable partner to the foundation, bringing his curiosity and clarity to our events and helping raise awareness of our work. But he’s also become a powerful advocate for global health in his own right. I don’t know anyone else who could turn a book about tuberculosis into a number one New York Times bestseller.

Everything Is Tuberculosis is poignant, smart, and at times infuriating. At its heart is the story of a boy named Henry, whom John met at a TB clinic in Sierra Leone. Henry was just six when he started showing classic signs of the disease: fatigue, weight loss, night sweats. But the first tests he got came back negative, so he was sent home from the hospital. By the time he was eventually diagnosed, Henry was already very sick.

He began treatment with the standard cocktail of decades-old antibiotics. It’s a brutal regimen that involves months of pills, painful injections, constant side effects—and, once the infection starts to subside, aching hunger from having an appetite again. The drugs only work if they’re taken consistently and on schedule, but that’s often unrealistic for patients. In much of the world, TB treatment means walking miles to a clinic, missing work or school, going into debt, and facing social stigma and isolation. Even though Henry’s mom did everything she could to support him, there were interruptions to his treatment, and eventually the TB became drug-resistant.

In the end, Henry got lucky. Even as he got sicker and ran out of options, his doctors wouldn’t give up on him. They fought to get him access to a personalized drug regimen—something that’s rarely available to kids in poor countries. That care ended up saving his life, and today Henry is thriving. After years stuck in the hospital, he’s caught up academically and now in university (and even has a YouTube channel where he shares his journey and advocates for other TB patients). John doesn’t romanticize Henry’s story as some kind of miracle. Instead, he uses it as proof: that TB is curable, that good care works, and that the real question isn’t whether we can save lives—but whether we’re willing to make that care available to everyone.

Even though John finished writing the book last year, he nails the urgency of this moment. He shows how a disease that most people in rich countries have forgotten is still killing over a million people a year, and how easily that number could keep climbing. That’s especially true now, as foreign aid cuts disrupt TB care across the globe. Henry might not be alive today if it weren’t for organizations like Partners In Health—funded in part by U.S. health aid—which fought to get him the treatment he needed. These aid cuts will be devastating for kids like him, who may lose access to treatment altogether. They’ll also lead to more interrupted care, more cases, more drug resistance, and more strains of an infectious disease that will be harder and more expensive for the entire world to contain.

This is a book about the central challenge of global health today: the reality that, in John’s words, “the cure is where the disease is not, and the disease is where the cure is not.”

A book about tuberculosis could be pretty boring, but John makes it super compelling by weaving in TB’s long and strange history, from the myth that it only afflicted white people, to the theory that it inspired creative genius, to its influence on Victorian beauty standards. (I didn’t know about those last two… or the Stetson hats.) If you’re familiar with John’s work, this approach won’t surprise you. He has a gift for getting people to care about things they might not think are “for me,” whether that’s poetry, astrophysics, or infectious disease.

John ends Everything Is Tuberculosis with a stirring call to action. He makes the case that saving lives from TB isn’t really a scientific challenge anymore; it’s a moral one. I largely agree. But I also think there are more reasons for hope than the book lets on.

While John is clear-eyed about the failures of the past and present—the slow pace of progress, the sky-high prices of new TB drugs, the inequality that determines who gets treated and who doesn’t—he doesn’t spend much time on what comes next. Having spent the last two-and-a-half decades investing in the science behind TB care through the Gates Foundation, I’ve seen a different side of the story. I know what’s in the pipeline, and I know what’s possible.

Today, we’re closer than ever to breakthroughs that could change everything about how we treat and even prevent TB: shorter drug regimens, better diagnostics, and even vaccines. These tools will only make a difference if they’re affordable enough to reach kids like Henry. But I think it’s important to recognize that the companies often criticized for pricing are also, ironically, the only ones that have been willing to invest in TB at all. We need to keep working with them as partners, keep the innovation coming, and keep bringing costs down.

If we do, we can make Henry’s story of survival the norm, not the exception—and make tuberculosis a disease of the past, not the future.

In the introduction to his latest book, How to Feed the World, Vaclav Smil writes that “numbers are the antidote to wishful thinking.” That one line captures why I’ve been such a devoted reader of this curmudgeonly Canada-based Czech academic for so many years. Across his decades of research and writing, Vaclav has tackled some of the biggest questions in energy, agriculture, and public health—not by making grand predictions, but by breaking down complex problems into measurable data.

Now, in How to Feed the World, Vaclav applies that same approach to one of the most pressing issues of our time: ensuring that everyone has enough nutritious food to eat. Many discussions about feeding the world focus on increasing agricultural productivity through improved seeds, healthier soils, better farming practices, and more productive livestock (all priorities for the Gates Foundation). Vaclav, however, insists we already produce more than enough food to feed the world. The real challenge, he says, is what happens after the food is grown.

This kind of argument is classic Vaclav—questioning assumptions, forcing us to rethink the way we frame problems, and turning conventional wisdom on its head. His analysis is never about the best- or worst-case scenarios; it’s about what the numbers actually tell us.

And the numbers tell a striking story: Some of the world’s biggest food producers have the highest rates of undernourishment. Globally, we produce around 3,000 calories per person per day—more than enough to feed everyone—but a staggering one-third of all food is wasted. (In some rich countries, that figure climbs to 45 percent.) Distribution systems fail, economic policies backfire, and food doesn’t always go where it’s needed.

I’ve seen this firsthand through the Gates Foundation’s work in sub-Saharan Africa, where food insecurity is driven by low agricultural productivity and weak infrastructure. Yields in the region remain far lower than in Asia or Latin America, in part because farmers rely on rain-fed agriculture rather than irrigation and have limited access to fertilizers, quality seeds, and digital farming tools. But even when food is grown, getting it to market is another challenge. Poor roads drive up transport costs, inadequate storage leads to food going bad, and weak trade networks make nutritious food unaffordable for many families.

And access is only part of the problem. Even when people get enough calories, they’re often missing the right nutrients. Malnutrition remains one of the most critical challenges the foundation works on—and it’s more complex than eating enough food. While severe hunger has declined globally, micronutrient deficiencies remain stubbornly common, even in wealthy countries. One of the most effective solutions has been around for nearly a century: food fortification. In the U.S., flour has been fortified with iron and vitamin B since the 1940s. This simple step has helped prevent conditions like anemia and neural tube defects and improve public health at scale—close to vaccines in terms of lives improved per dollar spent.

One of the most interesting parts of the book is Vaclav’s exploration of how human diets evolved. Across civilizations, people independently discovered that pairing grains with legumes created complete protein profiles—whether it was rice and soybeans in Asia, wheat and lentils in India, or corn and beans in the Americas. These solutions emerged from practical experience long before modern science could explain why they worked so well.

But just as past generations adapted their diets to available resources, we’re now facing new challenges that require us to adapt in different ways. Technology and innovation can help. They’ve already transformed the way we produce food, and they’ll continue to play a role. Take aquaculture: Once a tiny industry, it’s grown over the past 40 years to supply more seafood for the world than traditional fishing—a scalable way to meet global protein demands. The Green Revolution is another example. Beginning in the 1960s, innovations in higher-yielding crops, more effective fertilizers, and modern irrigation prevented widespread famine in India and Mexico. These changes were once seen as unlikely, too.

New breakthroughs could drive even more progress. CRISPR gene editing, for instance, could help develop crops that are more resilient to drought, disease, and pests—critical for farmers facing the pressures of climate change. Vaclav warns that we can’t count on technological miracles alone, and I agree. But I also believe that breakthroughs like CRISPR could be game-changing, just as the Green Revolution once was. The key is balancing long-term innovation with practical solutions we can implement immediately.

And some of these solutions aren’t about producing more food at all—they’re about wasting less of what we already have. Better storage and packaging, smarter supply chains, and flexible pricing models could significantly reduce spoilage and excess inventory. In a conversation we had about the book, Vaclav pointed out that Costco (which might seem like the pinnacle of U.S. consumption) stocks fewer than 4,000 items, compared to 40,000-plus in a typical North American supermarket.

That kind of efficiency—focusing on fewer, high-turnover products—reduces waste, lowers costs, and ultimately eases pressure on global food supply, helping make food more affordable where it is needed most.

How to Feed the World had a lot to teach me—and I’m sure it will teach you a lot, too. Like all of Vaclav’s best books, it challenges readers to think differently about a problem we thought we understood. Growing more and better food remains crucial—especially in places like sub-Saharan Africa, where there simply isn’t enough. But as the world’s population approaches 10 billion, increasing agricultural productivity alone won’t solve hunger and malnutrition. We also need to ensure that food is more accessible and affordable, less wasted, and just as nutritious as it is abundant.

After all, the goal isn’t to make more food for its own sake—it’s to feed more people.

When people ask me about artificial intelligence, their questions often boil down to this: What should I be worried about, and how worried should I be? For the past year, I've responded by telling them to read The Coming Wave by Mustafa Suleyman. It’s the book I recommend more than any other on AI—to heads of state, business leaders, and anyone else who asks—because it offers something rare: a clear-eyed view of both the extraordinary opportunities and genuine risks ahead.

The author, Mustafa Suleyman, brings a unique perspective to the topic. After helping build DeepMind from a small startup into one of the most important AI companies of the past decade, he went on to found Inflection AI and now leads Microsoft’s AI division. But what makes this book special isn’t just Mustafa’s firsthand experience—it’s his deep understanding of scientific history and how technological revolutions unfold. He's a serious intellectual who can draw meaningful parallels across centuries of scientific advancement.

Most of the coverage of The Coming Wave has focused on what it has to say about artificial intelligence—which makes sense, given that it's one of the most important books on AI ever written. And there is probably no one as qualified as Mustafa to write it. He was there in 2016 when DeepMind’s AlphaGo beat the world’s top players of Go, a game far more complex than chess with 2,500 years of strategic thinking behind it, by making moves no one had ever thought of. In doing so, the AI-based computer program showed that machines could beat humans at our own game—literally—and gave Mustafa an early glimpse of what was coming.

But what sets his book apart from others is Mustafa’s insight that AI is only one part of an unprecedented convergence of scientific breakthroughs. Gene editing, DNA synthesis, and other advances in biotechnology are racing forward in parallel. As the title suggests, these changes are building like a wave far out at sea—invisible to many but gathering force. Each would be game-changing on its own; together, they’re poised to reshape every aspect of society.

The historian Yuval Noah Harari has argued that humans should figure out how to work together and establish trust before developing advanced AI. In theory, I agree. If I had a magic button that could slow this whole thing down for 30 or 40 years while humanity figures out trust and common goals, I might press it. But that button doesn’t exist. These technologies will be created regardless of what any individual or company does.

As is, progress is already accelerating as costs plummet and computing power grows. Then there are the incentives for profit and power that are driving development. Countries compete with countries, companies compete with companies, and individuals compete for glory and leadership. These forces make technological advancement essentially unstoppable—and they also make it harder to control.

In my conversations about AI, I often highlight three main risks we need to consider. First is the rapid pace of economic disruption. AI could fundamentally transform the nature of work itself and affect jobs across most industries, including white-collar roles that have traditionally been safe from automation. Second is the control problem, or the difficulty of ensuring that AI systems remain aligned with human values and interests as they become more advanced. The third risk is that when a bad actor has access to AI, they become more powerful—and more capable of conducting cyber-attacks, creating biological weapons, even compromising national security.

This last risk—of empowering bad actors—is what leads to the biggest challenge of our time: containment. How do we limit the dangers of these technologies while harnessing their benefits? This is the question at the heart of The Coming Wave, because containment is foundational to everything else. Without it, the risks of AI and biotechnology become even more acute. By solving for it first, we create the stability and trust needed to tackle everything else.

Of course, that’s easier said than done.

While previous transformative technologies like nuclear weapons could be contained through physical security and strict access controls, AI and biotech present a fundamentally different challenge. They're increasingly accessible and affordable, their development is nearly impossible to detect or monitor, and they can be used behind closed doors with minimal infrastructure. Outlawing them would mean the good guys unilaterally disarm while bad actors forge ahead anyway. And it would hurt everyone because these technologies are inherently dual-use. The same tools that could be used to create biological weapons could also cure diseases; the same AI that could be used for cyber-attacks could also strengthen cyber defense.

So how do we achieve containment in this new reality? It’s hardly fair to complain that Mustafa hasn’t single-handedly solved one of the most complex problems humanity has ever faced. Still, he lays out an agenda that’s appropriately ambitious for the scale of the challenge—ranging from technical solutions (like building an emergency off switch for AI systems) to sweeping institutional changes, including new global treaties, modernized regulatory frameworks, and historic cooperation among governments, companies, and scientists. When you finish his list of recommendations, you might wonder if we can really accomplish all this in time. But that’s precisely why this book is so important: It helps us understand the urgency while there’s still time to act.

I’ve always been an optimist, and reading The Coming Wave hasn’t changed that. I firmly believe that advances in AI and biotech could help make breakthrough treatments for deadly diseases, innovative solutions for climate change, and high-quality education for everyone a reality. But true optimism isn’t about blind faith. It’s about seeing both the upsides and the risks, then working to shape the outcomes for the better.

Whether you’re a tech enthusiast, a policymaker, or someone simply trying to understand where the world is heading, you should read this book. It won’t give you easy answers, but it will help you ask the right questions—and leave you better prepared to ride the coming wave, instead of getting swept away by it.

I didn’t like biology when I was a kid. I remember dissecting a flatworm in high school and thinking, “What relevance does this have for my life?” The answer, of course, is a great deal—but at the time, I didn’t see the connection between a worm’s biology and a person’s. It wasn’t until I started learning about global health that I began to fully understand and appreciate the subject.

If I had been able to read The Song of the Cell by Siddhartha Mukherjee in school, I might have fallen in love with biology a lot earlier. He does a terrific job of explaining in clear, accessible language not only how cells work but why they are the foundation of all life.

Although he’s a Pulitzer Prize-winning author, Mukherjee is primarily an oncologist whose passion for the subject of cellular biology comes through on every page. Early in the book, he writes, “I love looking at cells in the way that a gardener loves looking at plants—not just at the whole, but also the parts within the parts.” The result is just as good as his two previous books: The Emperor of All Maladies, which is about cancer, and The Gene, which you can probably guess the subject of.

The Song of the Cell starts by helping you understand the evolution of life. When life first emerged on our planet, it was in the form of single-celled organisms. (The Vital Question by Nick Lane is another terrific book that tackles this topic.) Billions of years later, the human body is home to hundreds of highly specialized cells, which all work in harmony with one another to help you grow and continue to function throughout adulthood. Mukherjee does a great job explaining how every dysfunction—every illness or consequence of aging—eventually comes down to something going wrong with one of these cells.

Although it’s been nearly two centuries since two German scientists first proposed cell theory—the idea that all organisms are made up of cells—our understanding of how to manipulate the building blocks of life to treat disease is still in its relative infancy. Mukherjee spends a lot of time exploring the history and current state of cell therapy, which involves taking your cells out, growing new ones, and then putting them back in.

The most successful and best-known type of cell therapy today involves stem cells. Unlike most cells in the human body, stem cells are a blank canvas. Think of them as potential, with the ability to become almost any cell in the body. When an embryo is first formed in the womb, it’s almost entirely made up of these blank canvases. By the time you’re an adult, you have a lot fewer of them—but the stem cells you do have play a key role in replacing damaged cells. As you get older, they age with you. Their DNA gets damaged over time and they become less effective, which means that your tissue takes longer to replenish. (If you have reached the age where it takes a lot longer to recover from an injury than it used to, your aging stem cells deserve some of the blame.)

Scientists have long been excited about the therapeutic potential of stem cells. The hope is that, one day, we’ll be able to use stem cells to revert your cells to a younger, healthier state. I’m still optimistic that will be the case eventually, but I think the initial excitement was a bit overoptimistic. For example, researchers had grand visions of repairing a broken spine with neural stem cells that would regrow the spinal cord. That hasn’t panned out yet, and to date, there is only one form of successful stem cell therapy: hematopoietic stem cell transplantation, which involves blood cells.

The history of the stem cell transplant is equal parts amazing, inspiring, and heartbreaking. Mukherjee devotes an entire chapter to the subject. In 1963, a team at the Fred Hutchinson Cancer Research Center—affectionately known here in Seattle as Fred Hutch—knew that the most effective way to treat leukemia was to destroy the cancer cells with chemotherapy. But there was a problem: The process destroyed the immune system.

If left untreated, leukemia is usually fatal. So, they came up with a bold solution. The doctors would dose a patient with chemotherapy and then give them stem cells from a donor to rebuild the entire immune system from scratch. When the procedure was first done, it was very risky, and the initial patients died. Mukherjee interviewed some of the nurses who worked in the leukemia wing at Fred Hutch. It’s hard to read their stories of watching their patients—many of whom were children—struggle to recover after the procedure.

Slowly but surely, over time, both the operation itself and the ongoing survival rate improved. Today, hematopoietic stem cell transplantation is a common treatment for leukemia and other cancers like multiple myeloma. And research is ongoing into whether it could be used to treat deadly diseases like HIV and sickle cell disease.

The journey to effective cell therapies has been long and bumpy, but I’m optimistic that our new understanding of cells will soon lead to massive breakthroughs. As Mukherjee explains in the book, we are just starting to grasp how cells interact with one another. “We can name cells, and even systems of cells, but we have yet to learn the songs of cell biology,” he writes. We don’t yet know how cells work together to create the cohesive melody that powers the human body. Once we learn those songs—as he so elegantly puts it—I believe we will unlock transformative new treatments that will change how we think about medicine.

If I could go back in time and tell my teenage self how biology is relevant to his life, I would say this: All of us will get sick at some point. All of us will have loved ones who get sick. To understand what’s happening in those moments—and to feel optimistic that things will get better—you need a foundational knowledge about the building blocks of life. Mukherjee understands that “to locate the heart of normal physiology, or of illness, one must look, first, at cells.” The world of medicine moves very quickly, and The Song of the Cell will help you appreciate just how far we’ve come to achieve each breakthrough.

Long before I became a software engineer, I thought like a civil engineer. As a kid, I’d look around my Seattle neighborhood and wonder how all those power lines, telephone cables, sewers, and water pipes worked. I still remember when the city separated its sewage and stormwater systems, a massive project that was all about improving water quality and reducing flooding.

I wish I’d had Grady Hillhouse’s book Engineering in Plain Sight back then. It takes all those mysterious structures you see every day and explains them in a way that's both entertaining and enlightening.

For instance, when you see a bunch of cables and boxes on a utility pole, do you know what each one does? I sort of did, but I understand it much better since reading this book. Hillhouse breaks it all down, explaining why there are so many different components up there and showing what each one does.

Hillhouse is a former civil engineer—he now works full-time on his YouTube channel, Practical Engineering—but you don’t need any background in the subject to appreciate the explanations in this book. He uses straightforward language and a lot of illustrations to make it all easy to understand. He explains why we have voltage step-downs on utility poles and what those mysterious backflow preventers are that you see in water systems. He also gets into the nitty-gritty of things like natural gas distribution and water systems. I was particularly fascinated by the sections on water and sewage systems.

I also appreciate how the book encourages curiosity. It’s not about becoming an expert on every piece of infrastructure you see, but about sparking that “aha” moment when you finally understand what something is and why it’s there. Personally, I’m curious about cell towers; Hillhouse explains how they work and why they’re designed the way they are, which is both interesting and reassuring.

One of the coolest aspects of Engineering in Plain Sight is how it ties everyday observations to larger engineering principles. For instance, why do some countries have big water tanks on top of houses while others don’t? It’s all about the reliability of the local water distribution system. In places with less reliable systems, those tanks ensure a steady supply of water. It’s a simple solution to a complex problem, and it’s these kinds of insights that make the book so rewarding.

The book's engaging style makes it a perfect read for the holidays. It's informative without being dry, and you can pick it and put it down without losing track of the narrative. It's the kind of book that makes you look at the world a little differently, and maybe even appreciate the engineering marvels that keep our modern lives running smoothly. This would have been a perfect holiday gift for my younger self, and I think it would be great for anyone who is similarly curious about the things that make modern life possible.

When Hannah Ritchie arrived at the University of Edinburgh in 2010, she was eager to learn how to solve the world’s biggest challenges. But over the next four years, she became convinced—through college lectures and keeping up with the news—that the most existential environmental issues were only getting worse. Like so many people, including many climate activists today, she believed she was “living through humanity’s most tragic period.” By the time she graduated with a degree in environmental geoscience, Ritchie was ready to find a new career path entirely.

Fortunately, she found Hans Rosling first. A Swedish physician and statistician, Rosling was renowned for using data to prove that by so many metrics of human well-being, despite such common misconceptions otherwise, the world was making progress. His life and work have influenced my own tremendously—and just a few pages into Ritchie’s essential and hopeful new book, Not the End of the World: How We Can Be the First Generation to Build a Sustainable Planet, it became clear that she was carrying on his tremendous legacy.

Like Rosling, Ritchie has a perspective shaped less by the news than by the facts—something she’s refined through her work as lead researcher at Our World in Data, an online platform that publishes some of my favorite data-driven articles and graphics on global issues today. (The Gates Foundation is a funder.) Also like Rosling, she uses those facts to tell a surprisingly optimistic and often counterintuitive story, one that completely contradicts the doomsday-ism in most climate change conversations. 

After reading her whole book—which comes out in the U.S. on January 9, 2024, and in the U.K. on January 11—I can confidently say that Ritchie has done for the environment what Rosling spent his life doing for public health and global development.

A key way she does this is by tackling a word I don’t usually love, sustainability, head-on. As she explains it, there’s a misconception that the world was once sustainable, and that it’s been getting less and less so over time. But from the UN’s definition—“meeting the needs of the present without compromising the ability of future generations to meet their own needs”—it’s clear that there are two parts to this concept. Sustainability requires making sure everyone today can live a good, healthy life and not degrading the environment in a way that takes away opportunities from people tomorrow. 

Ritchie makes the case, convincingly, that the world has never been sustainable because both halves of the definition have never been achieved simultaneously.

The first half has never been achieved, period: For most of human history, half the population died before adulthood; while that statistic has improved drastically, five million kids a year still don’t make it to their fifth birthday.

Still, the progress that has been and will continue to be made on child mortality—along with six other measures of human well-being including hunger, maternal mortality, life expectancy, education, extreme poverty, and access to basic resources like clean water, energy, and sanitation—is why Hannah argues there is no better time to be alive than the present. That doesn’t negate the violence and instability we see around the world. But compared to the past, we’re closer than we’ve ever been to meeting the needs of people today and achieving the first half of the definition.

As for the second half, Ritchie analyzes seven big environmental problems we face today: air pollution, climate change, deforestation, food, biodiversity loss, ocean plastics, and overfishing. On most of these fronts, things are worse today than they were in the distant past. But on all of them, progress has been made recently, and we’re on a better trajectory than most people assume—even though that rarely makes the end-of-the-world headlines dominating the news.

In the United Kingdom, where Ritchie lives, individual carbon footprints are down to 1850s levels after peaking in the 1960s thanks to much more energy-efficient technologies and much less coal. In rich countries, per capita emissions are falling, and worldwide, we hit peak per capita emissions in 2012. The other “peaks” that people have been told to dread—peak population, peak fertilizer and agricultural land use, peak whaling, peak deforestation of the Amazon—are either already behind us or will be soon. Across many regions, threatened wildlife species are repopulating. Electricity, which too many of the world’s poorest live without, was cheaper across the board in 2019 than it was in 2009—and in that decade, solar and wind went from the priciest per unit to the cheapest. And on, and on, and on.

That doesn’t mean things aren’t bad, or there is no reason to worry. For example, air pollution globally still kills nine million people a year. And if we don’t get serious about combating climate change and dramatically reducing emissions, the consequences for people and the planet will be disastrous. The world is bad, but much better: Those two things can be true at once. So can a third: “The world can be much better.”

In each chapter, Ritchie provides tangible action that people, companies, and governments can take to build that better world—one where trade-offs between human well-being and environmental protection, between life today and life tomorrow, no longer have to be made. She also assigns responsibility to rich countries, the ones that built their wealth on fossil fuels, to continue investing in clean energy, making it cheaper, eliminating Green Premiums, and deploying those innovations to poor countries that otherwise can’t be expected to “leapfrog a long fossil-powered development path.” I couldn’t agree more.

I’ve written my own book on climate change, and I work on clean solutions daily with Breakthrough Energy. Still, I was surprised by how much Ritchie’s book—filled with all the numbers and charts a math nerd could dream of—managed to surprise me. I think everyone who reads it will feel the same, even those who consider themselves tuned in to environmental issues.

The reality is that it’s easier to track breaking news than trend lines. But if we don’t zoom out and look at the larger picture, we don’t just miss out on learning that progress has been made. We miss out on learning how. That’s why so many people’s intuitions on issues like lab-grown meat, dense cities, and nuclear energy—all pretty good for the planet—are, in Ritchie’s words, “so off.”

Perhaps that’s also why so many people believe the world is ending—and why even those who do believe we can build a better one don’t know where to start.

My recommendation? This book.

When you walk into my office, one of the first things you see is a huge version of the periodic table. It includes examples or representations of all 118 elements, like a clock with glow-in-the-dark dials for radium and a bottle of Pepto Bismol for bismuth. (Sometimes visitors are just as interested in the table as they are in whatever we’re meeting about—and I don’t blame them!)

Aside from being a neat piece of art, the periodic table reminds me of how one discovery can lead to countless others. All the complexity of the universe comes from the properties on that chart. Because we understand atoms, we can make chips, and therefore we can make software, and therefore we can make AI. Everything goes back to the periodic table.

But how exactly did the periodic table come to be? Anyone who has taken a grade school science class might remember that it was first proposed by the Russian chemist Dmitri Mendeleyev. But the table was actually the culmination of two-and-a-half millennia of scientific discovery.

Paul Strathern’s terrific book Mendeleyev’s Dream traces that journey all the way back to ancient Greece, when people first started questioning why the world is the way it is. It’s hard to imagine a time before science. But until Thales of Miletus figured out that the presence of seashell fossils on land must mean the entire world was once a sea, Strathern reminds us that people were more focused on questions of religion than on questions of science.

Strathern spends much of his book exploring chemistry’s roots in alchemy, which was one of the earliest forms of science. For centuries, many of the brightest minds—including Isaac Newton—were fascinated by the idea of turning base materials into gold or an elixir that made you immortal. Although the science proved to be faulty, alchemy inspired generations of scientists to think about how materials interact with each other.

Mendeleyev’s Dream sounds like a dense book, but Strathern keeps things light by writing about the many outrageous personalities who studied alchemy and chemistry over the years. One of the most entertaining chapters is about Paracelsus, a Swiss physician and alchemist from the 1500s. Paracelsus made important contributions to toxicology and medicine. He was also a quirky character with a flair for the dramatic. During one of his lectures, Strathern writes, “Paracelsus opened by announcing that he would now reveal the greatest secret in medical science. Whereupon he dramatically uncovered a pan of excrement.” (He’s a man after my own heart.)

Mendeleyev was also an unusual guy. He was known to get so angry that he would dance “with Rumpelstiltskin-like rage,” and the book’s title refers to his claim that the periodic table came to him in a dream. Regardless of its origins, there is no question of how significant a breakthrough this was. Other scientists had hinted at repeating patterns in the atomic weights of elements, but Mendeleyev was the first to lay them out—and fill in the gaps. He accurately predicted the existence of gallium and germanium before either element was discovered. For the first time, humanity had a road map to understanding the building blocks of the universe.

Mendeleyev’s Dream is the best book I’ve ever read on the periodic table. It helps you understand how it all got pieced together and why it’s so helpful. It’s also a fascinating look at how a new science develops. Strathern describes the story of the periodic table as “a wayward parable of human aspiration,” and I agree. The history of chemistry tells us as much about the evolution of human thinking as it does about the science of matter.

I occasionally check the bestseller lists for ideas about what to read next. A few weeks ago I looked at the New York Times’s nonfiction list and got quite a surprise. The latest book by Vaclav Smil, How the World Really Works, was number 8!

I have been a fan of Vaclav’s work for years—he is one of my favorite authors. But his style is not for everyone. Many of his books are dense and packed with data, and it is an understatement to say they have never sold especially well. So as an admirer of Vaclav’s work, I was excited to see his latest one in the top 10 list. The more people who read his books, the better. (I’m sure his new book got a boost from this largely positive review in the New York Times Book Review.)

What I love about How the World Really Works is that it sums up all of the incredible knowledge Vaclav has gained over the years. Most of his 50 books go into great detail about complex subjects including energy, manufacturing, shipping, and agriculture. He wrote an entire book on how diets in Japan have changed.

Because he has gone so deep into such specific topics, he is qualified to step back and write a broad overview for a general audience, which is what he has done with How the World Really Works. If you want a brief but thorough education in numeric thinking about many of the fundamental forces that shape human life, this is the book to read.

Energy is a great example. I have learned more about energy and its impact on society from Vaclav than from any other single source. In 2017 I reviewed his masterpiece Energy and Civilization: A History and wrote that “he goes deep and broad to explain how innovations in humans’ ability to turn energy into heat, light, and motion have been a driving force behind our cultural and economic progress over the past 10,000 years.”

But if you are not up for a long, dense book on the role of energy in human history—Energy and Civilization is 568 pages long and reads like an academic text—you can get the most important ideas by reading the first three chapters of How the World Really Works. They should be required reading for anyone who wants to have an informed opinion on climate change. All Vaclav wants is for people to look at all the areas of emissions—producing electricity, manufacturing, transportation, and so on—and propose realistic, economically viable plans for reducing emissions in each one.

As I wrote in my book on climate change, parts of which drew on Vaclav’s work, I am more optimistic than he is about the opportunity to innovate our way out of a climate disaster. But I highly recommend reading him on the subject because he is so good at explaining how the world’s energy systems work today. Chapter 1, which you can download for free below, is a great example—it covers fuels and the production of electricity.

Another good example of Vaclav’s approach is from the chapter on food. To help you understand the ways in which new sources of energy have allowed humans to grow crops and raise animals more efficiently, he portrays life on three different farms from three eras. He starts with a hypothetical farmer in western New York state in 1801 and explains all the laborious steps required for that person to harvest wheat. Then he skips ahead a century and takes you to eastern North Dakota, showing you all the advances, including plows and harvesters, that made farming far more efficient. Finally he goes to Kansas in 2021 and shows you how things have changed even more dramatically in the past century.

As usual, Vaclav has crunched all the numbers, so he can explain all of this change in both qualitative and quantitative ways. “In two centuries,” he writes, “the human labor to produce a kilogram of American wheat was reduced from 10 minutes to less than two seconds.”

And then he puts that statistic in an even broader context, showing how higher crop yields freed up people to move off of farms and into urban areas where they could collaborate on other innovations. “Most of the admired and undoubtedly remarkable technical advances that have transformed industries, transportation, communication, and everyday living,” he writes, “would have been impossible if more than 80 percent of all people had to remain in the countryside in order to produce their daily bread… or their daily bowl of rice.”

Although Vaclav has strong opinions on many subjects, they are always grounded in facts. And when he weighs in on a huge problem like climate change, he avoids extremes. As he told one interviewer, “What we need is the dull, factually correct and accurate middle. Because only from that middle will come the solutions.”

I disagree with one word in that quote. How the World Really Works is certainly factually correct and accurate, but it is never dull. It is a compelling and highly readable book that leaves readers with the fundamental grounding needed to help solve the world’s toughest challenges.

Of all the subjects I’ve been learning about lately, one stands out for its mind-boggling complexity: understanding how the cells and connections in our brains give rise to consciousness and our ability to learn.

Thanks to better instruments for observing brain activity, faster genetic sequencing, and other technological improvements, we’ve learned a lot in recent years. For example, we now understand more about the different types of neurons that make up the brain, how neurons communicate with one another, and which neurons are active when we’re performing all kinds of tasks. As a result, many people call this the golden era of neuroscience.

But let’s put this progress in context. We’re only beginning to understand how a worm’s brain works—and it has only 300 neurons, compared with our 86 billion. So you can imagine how far we are from getting answers to the really big, important questions about brain function, including what causes neurodegeneration and how we can block it. Watching helplessly as my dad declined from Alzheimer’s made me feel as if this era is not yet a golden era. I think it’s more like an early dawn.

Over the years, I’ve read quite a few books about the brain, most of them written by academic neuroscientists who view it through the lens of sophisticated lab experiments. Recently, I picked up a brain book that’s much more theoretical. It’s called A Thousand Brains: A New Theory of Intelligence, by a tech entrepreneur named Jeff Hawkins.

I got to know Hawkins in the 1990s, when he was one of the pioneers of mobile computing and co-inventor of the PalmPilot. After his tech career, he decided to work with a singular focus on just one problem: making big improvements in machine learning. His platform for doing that is a Silicon Valley–based company called Numenta, which he founded in 2005.

Machine learning has incredible promise. I believe that in the coming decades we will produce machines that have the kind of broad, flexible “general intelligence” that would enable them to help us address truly complex, multifaceted challenges like improving medicine through a more advanced understanding of how proteins fold. Nothing we call AI today has anything like that kind of intelligence.

As Hawkins puts it, “There is no ‘I’ in AI.” Computers can beat a grandmaster in chess, but they don’t know that chess is a game. Hawkins argues that we can’t achieve artificial general intelligence “by doing more of what we are currently doing.” In his view, understanding much more about the part of the brain called the neocortex is key to developing true general AI, and that’s what this book is about.

A Thousand Brains is appropriate for non-experts who have little background in brain science or computer science. It’s filled with fascinating insights into the architecture of the brain and tantalizing clues about the future of intelligent machines. In the foreword, the legendary evolutionary biologist Richard Dawkins says the book “will turn your mind into a maelstrom of … provocative ideas.” I agree.

Hawkins begins by walking us through the basics of the neocortex, which makes up 70 percent of the human brain. It’s responsible for almost everything we associate with intelligence, such as our ability to speak, create music, and solve complex problems.

Borrowing from the work of neuroscientist Vernon Mountcastle, Hawkins reports that the basic circuit of the neocortex is called a “cortical column,” which is divided into several hundred “minicolumns” with about a hundred individual neurons. He argues that “our quest to understand intelligence boils down to figuring out what a cortical column does and how it does it.”

He believes that the basic function of the cortical column is to make constant predictions about the world as we move through it. “With each movement, the neocortex predicts what the next sensation will be,” Hawkins writes. “If any input doesn’t match with the brain’s prediction … this alerts the neocortex that its model of that part of the world needs to be updated.”

The name of the book comes from Hawkins’s conclusion that cortical columns operate in parallel, each making separate predictions about what the next sensory input will be. In other words, each column functions as its own separate learning machine.

If Hawkins is right that the only viable path to artificial general intelligence is by replicating the workings of the neocortex, that means it’s unlikely that intelligent machines will supplant or subjugate the human race—the kind of thing you see in classic sci-fi movies like The Matrix and The Terminator. That’s because the neocortex operates differently from parts of the brain that evolved much earlier and that drive our primal emotions and instincts.

“Intelligent machines need to have a model of the world and the flexibility of behavior that comes from that model, but they don’t need to have human-like instincts for survival and procreation,” Hawkins writes. In other words, we will eventually be able to create machines that replicate the logical, rational neocortex without having to wrap it around an old brain that’s an “ignorant brute” wired for fear, greed, jealousy, and other human sins. That’s why Hawkins dismisses the notion that humans will lose control of the machines they create.

Unfortunately, we may still need to worry about the dark side of artificial intelligence. Even if intelligent machines replicate only the “new brain” and are not saddled with an “old brain,” some people will still try to use them for bad purposes. Sadly, that is human nature.

In the end, I come back to my starting premise that we’re still early in our understanding of the human brain compared with just about every other part of our world. We don’t know yet whether Hawkins’s Thousand Brains Theory will hold up to experimental scrutiny. And even if it does, we still don’t know how to replicate cortical columns with digital technologies.

All I know for sure is that I’ll be reading a lot more about this topic. My hope is that it will help lead to great breakthroughs in the way we go about solving the world’s hardest problems.

In 2016, I called The Gene: An Intimate History one of my favorite books of the year. The book’s author, Siddhartha Mukherjee, decided to write it largely because of a huge advance that had received far less attention than it deserved: Biochemist Jennifer Doudna and microbiologist Emmanuelle Charpentier’s discovery of “genetic scissors” that allow scientists to cut any DNA sequence with incredible precision. Doudna and Charpentier’s discovery earned them the 2020 Nobel Prize in Chemistry.

The “scissors” Doudna and Charpentier discovered are known as CRISPR (pronounced like “crisper”), which stands for Clustered Regularly Interspaced Short Palindromic Repeat. The CRISPR system is a sophisticated defense that bacteria evolved to disarm invading viruses, similar to the way fungi developed penicillin to protect themselves against bacterial infection. The CRISPR system makes it much easier for scientists to alter human and other genomes in beneficial ways, such as repairing gene mutations that cause awful diseases like cystic fibrosis.

In the five years since Mukherjee wrote his book, researchers have done a remarkable job of honing the CRISPR system for medical and agricultural applications, and my excitement about CRISPR has grown from super high to off the charts. CRISPR has fundamentally changed my thinking about what’s possible for improving the health and nutrition of families in poor countries—and how quickly. For example, it took more than 30 years to develop the first effective vaccine for malaria (which the Gates Foundation helped fund)—and that vaccine has an efficacy of only about 50 percent against severe malaria in the first year, dropping in subsequent years. Thanks to the CRISPR system, it’s very likely that our grantees will be able to develop much more effective vaccines in the next five years.

The foundation is investing in many other projects that use the CRISPR system, such as:

• plant varieties that can withstand the effects of climate change
• a new suite of tools called programmable medical therapies, which could greatly speed up the development of treatments for new viruses and head off future pandemics
• quick, inexpensive ways of diagnosing diseases in poor countries
• monoclonal antibodies that could target and kill the pathogens that cause malaria and AIDS.

When I heard that one of my favorite authors, Walter Isaacson, was working on a book about CRISPR and its inventor, I was eager to read it. The title, The Code Breaker: Jennifer Doudna, Gene Editing, and the Future of the Human Race, suggests that the book is a biography of Doudna, but its scope is broader than that. In fact, Isaacson goes into detail about every CRISPR researcher the foundation is supporting (and many others as well). I found the book to be valuable on a number of levels.

First, it’s great to read a story about scientific discovery with a woman at its center. As a dad, I was touched by the sections in which Doudna’s father, Martin, who was a professor, helps stoke his daughter’s passion for science and her confidence to pursue it at the highest levels. Unfortunately, Martin died of melanoma before his daughter achieved international fame.

Second, I thought Isaacson did a good job of highlighting the most important ethical questions that arise from the CRISPR revolution. Many applications of CRISPR are inarguably good, such as using it to cure blood diseases like sickle cell anemia and beta thalassemia. In these cases, scientists are alleviating human suffering in a way that does not alter the human germline. In other words, the edits affect only the person who receives them and do not get passed along to subsequent generations.

But some scientists are not treating the germline as a red line. As Isaacson covers with nuance, three years ago a Chinese researcher named He Jiankui used CRISPR to edit the genomes of human embryos and then implanted these embryos in women who consented to carrying them to term. Two babies, named Nana and Lulu, have now been born from those embryos. If Nana and Lulu someday have babies of their own, their babies will inherit the genetic modifications Nana and Lulu received. The Chinese researcher’s intentions were good—helping HIV-positive couples give birth to children who had a gene that would confer resistance to infection with HIV—but he disregarded scientific guardrails established by Chinese and American authorities.

While the foundation is not funding any CRISPR projects that involve germline editing, Doudna says it doesn’t make sense to ban germline editing outright. For one thing, she argues, editing that does not involve germline cells, known as “somatic editing,” has limitations. As I mentioned above, scientists are now able to cure sickle cell anemia, but that somatic approach is out of reach for the vast majority of the four million people who suffer from the disease, because it’s such a complex and expensive procedure and can only be done in top-tier hospitals. The germline version might be much less expensive and therefore much more accessible in low- and middle-income countries, which are home to most of the 300,000 babies born with sickle-cell disease each year.

But then another ethical dilemma arises. In Isaacson’s words, “Let’s suppose that researchers show that editing out the sickle-cell mutation is safe. Would there then be any reason to prohibit parents from having the gene edited out when they conceive children?” His answer: maybe. Isaacson introduces us to a California teen named David Sanchez, who gets sickle-cell crises so debilitating that he had to drop out of high school. When one of Sanchez’s doctors told him that “maybe one day with CRISPR they could go in and change the gene in the embryo so that the kid, when it’s born doesn’t have sickle cell,” Sanchez responded in a way you might not expect: “I think it should be up to the kid later,” he said. “There’s a lot of things that I learned having sickle cell. Because I had it, I learned patience with everyone.” The moral of the story: figuring out what’s right to edit into or out of a human genome is not clear cut.

The Code Breaker is highly accessible for non-scientists. And that’s super important, because the ethics of CRISPR’s use are not clear. Doudna is now spending a big portion of her time focused on these moral and ethical issues, especially the potential for genetic editing to exacerbate inequality. As she says to Isaacson, “If you think we face inequalities now, imagine what it would be like if society became genetically tiered along economic lines and we transcribed our financial inequality into our genetic code.”

As with artificial intelligence, facial recognition, and other digital technologies, the public should play an engaged role in drawing the ethical lines. That’s the best way to ensure that the world maximizes the potential for these remarkable innovations to improve the human condition.

The journalist Elizabeth Kolbert has created a fascinating beat for herself. I’m not sure how she would describe the field she covers, but I’d call it something like “humanity’s impact on nature and our attempts to control it.”

That dry description doesn’t really do Elizabeth’s work justice, though. She brings the subject to life with well-told stories, thorough reporting, and portraits of interesting people. I loved her book The Sixth Extinction, which won a Pulitzer Prize in 2015. I read everything she writes in The New Yorker. And I was excited to have her as a guest talking about climate change on the podcast I did with Rashida Jones last year.

So I was looking forward to reading her new book, Under a White Sky: The Nature of the Future, which came out earlier this year. I’m glad I picked it up. Although I have some issues with the book, overall it is a fine example of her work and an insightful look at the role that scientists and engineers play at the intersection of nature and humans.

Under a White Sky is, as Elizabeth writes at the end, “a book about people trying to solve problems caused by people trying to solve problems.” Humans have affected so much of the planet’s land and oceans that we face a future without any precedent, she writes. The challenge for us is no longer just the control of nature—it is “the control of the control of nature.”

For example, the opening chapter is about how wildlife management officials, looking to control invasive aquatic weeds without the use of poisons, introduced Asian carp into a few American rivers in the 1960s. The idea was that the carp would eat the weeds, and they did. But—thanks to the construction of canals that connected the Mississippi and Great Lakes basins—the carp began invading other waterways and causing other problems, including threatening to kill off sport fish in the Great Lakes. So now the Army Corps of Engineers has built an electric barrier to try to keep out the fish that were introduced to keep out the weeds.

Elizabeth covers lots of other topics, including attempts to save coral reefs and to control flooding in southern Louisiana. I was especially interested to read her take on two subjects I’ve studied a lot over the years.

One is a concept known as gene drive. The term covers several approaches, but the basic idea is to use gene editing to rewrite the usual rules of gene inheritance, so that a given parent passes all of its genes on to its children (rather than just half of them). Elizabeth explains how gene drive might be used in Australia to control the invasive, poisonous cane toad—which needs to be controlled because it has spread like mad after being introduced by humans in the 1930s to get rid of a pest that was decimating the country’s sugar cane crops.

The other idea is geoengineering. It’s an umbrella term that describes various ways to lower the planet’s temperature by making temporary changes in the earth’s oceans or atmosphere. Geoengineering is a kind of “Break Glass in Case of Emergency” approach. It wouldn’t absolve us of the respon­sibility to reduce emissions; it would just buy us time to get our act together in avoiding a climate disaster.

As I’ve come to expect from Elizabeth’s work, she explains gene drive and geoengineering in a compelling and lucid way. You meet interesting people—including David Keith, one of the scientists who educated me on climate years ago and who’s doing some interesting research on geoengineering now. You learn about some of the ripple effects that human interventions can have, and you get a good sense of how scientists and engineers are trying to deal with them.

But the potential side effects of our attempts to control nature are only part of the story. Although it may not seem like it right now, while a pandemic is still going on, the human condition today is better than at any time in the past—and much of the progress is due to human discoveries, inventions, and interventions in nature. Humans created vaccines for COVID-19 decades faster than any vaccine had been invented before. Synthetic fertilizer, better seeds, and farm tools allow us to feed far more people with much less labor than in the past.

I’m glad that smart writers like Elizabeth are reminding us of the risks of trying to intervene in nature. But I wish she had also explored whether the risks are worth taking, or what the alternatives might be.

For example, there are many things we can do about climate change aside from dimming the sun, as I wrote in my book this year. (Geoengineering gets just a few paragraphs out of 230 pages.)

Similarly, gene drive isn’t just for toads. As I explained in this post a couple of years ago, it could be a powerful way to control the species of mosquito that spread malaria. Our foundation is funding some exciting work in this area, and we’re also part of the global conversation about its pros and cons. I’m glad there’s a vigorous debate going on in the global health community about the use of this technology.

I suspect I’m more of an optimist than Elizabeth is. I don’t think it’s inevitable that humans will keep degrading the environment forever. As the standard of living rises, population growth levels off and people start devoting resources to preserving and cleaning up the environment. We’re also developing new ways of understanding the impact we have on nature—including computer models that can predict how mosquito populations will respond to various attempts to kill them off.

Despite these reservations, I still recommend reading Under a White Sky. Elizabeth has a breezy, easy-to-read style, and her book is a good reminder that we need to watch out for the unforeseen effects of our actions. Even though that’s only half the story, it’s an important half.

The COVID-19 pandemic has sparked intense interest in and great questions about the immune system. Why would a virus kill some people while having little or no apparent effect on others—even those of similar age and background? What’s happening inside the body when it gets exposed to a novel virus? What happens when a vaccine gets injected into the arm? What is herd immunity? And so on.

If you’re asking these kinds of questions, you should pick up An Elegant Defense: The Extraordinary New Science of the Immune System, by Pulitzer Prize–winning New York Times reporter Matt Richtel. He wrote the book before the pandemic, which means there’s nothing here about COVID-19 or the virus that causes it. Nonetheless, Richtel’s timing was good, because his book gives you all the context you need to understand the science of immunity.

Even though I dropped out of college, I really enjoy reading textbooks. But I know most people who don’t have a degree in immunology prefer books with a story that brings scientific concepts to life. That’s exactly how Richtel constructs this book. He anchors it in the tales of four real people whose health challenges illustrate the immune system’s features and bugs. The most poignant of these is the story of Richtel’s lifelong friend Jason Greenstein, a traveling salesman who was diagnosed with Hodgkin’s lymphoma. (I came to know this form of cancer all too well when my friend and Microsoft co-founder, Paul Allen, was diagnosed with it while we were working together. He died in October 2018 of a different form of cancer.)

In the process of reading about the four people in An Elegant Defense, you absorb quite a lot of useful and interesting science. For example, you’ll learn about all the key components of the immune response … the ways pathogens can outsmart our defenses … how women’s heightened immune systems lead to longer life on average … how sleep, meditation, and exercise improve immune function … why the pursuit of immortality is a fool’s errand … and why following the “five second rule” for eating food that falls on the floor is actually a healthy thing to do.

Most important, you’ll come away with a much better understanding of our immune system’s awesome complexity—and the delicate, even precarious, tradeoffs inherent in its workings.

Millions of years of evolution have produced an immune system with multiple ingenious mechanisms for detecting and killing invaders, even ones it has never seen before. But seek and destroy is less than half of the story. Since the 1980s, immunologists have learned that the immune system is tuned to find a balance “between attacking and neutralizing real dangers and showing sufficient restraint such that its potency didn’t destroy the body,” Richtel writes. “This is what makes our defense so elegant.” In other words, evolution found a Goldilocks set point for the human immune system. When it’s working well, it’s aggressive enough to fend off most invaders but not so powerful that it’s constantly attacking its own cells.

One of the most exciting developments in all of science and medicine is our growing ability to tweak this balance in precise ways—an area I track closely and that Richtel covers well. In the course of telling the story of his friend Jason Greenstein’s cancer, Richtel describes effective new treatments that help our immune systems target our own cells that have gone rogue. Through the stories of lupus patient Merredith Branscombe and rheumatoid arthritis patient Linda Segre, Richtel helps us understand new drugs that tamp down the immune system for those who suffer from debilitating autoimmune disorders.

These treatments fall into a class of drugs known as “biologics,” which now make up more than a quarter of the entire pharmaceutical market. Traditional medicines are based on small molecules with relatively simple chemical structures. Biologics, in contrast, are derived from living cells and are much more complex in structure, making them expensive to manufacture and a big factor in the rising costs of health care. What makes them so appealing to doctors and patients is that they don’t go everywhere in the body; they target and modulate specific chemicals or cells at the core of the immune system’s responses. Therefore, they’re usually less toxic and more effective than traditional drugs.

The best-known example of this type of drug is Humira. I have friends who take it and describe it in glowing terms compared to other treatments they’ve been prescribed. It’s made up of synthetic antibodies that dial down the production of a protein that’s thought to be at the root of a dozen major autoimmune disorders, including Crohn’s disease and ulcerative Colitis. (Incidentally, the term monoclonal antibody, which includes drugs like Humira, is abbreviated “mab,” which is why the generic name of so many new drugs ends in that suffix. You’ll notice it in most of the pharmaceutical ads you see on TV or in print.)

We’re just at the beginning of the mab revolution. For example, as scientists develop ways to make monoclonal antibodies cheaper and easier to administer, they could help fight diseases that disproportionately affect people in poor countries. I’m also excited about their potential for sparking advances in treatments for Alzheimer’s disease, which my dad had for years before he died last fall. The immune system and the inflammation that it produces may well play key roles in neurodegenerative disease.

Back in simpler, pre-COVID-19 times, I read and reviewed Dr. Siddhartha Mukherjee’s The Gene: An Intimate History. An Elegant Defense left me with the same sense of awe I had when I read The Gene. I marvel over the intricacy and sophistication of the systems that make up the human body. Now that I’ve read , I have a deeper, more nuanced appreciation for the system that is at the core of humanity’s fight against COVID-19 and everything our foundation’s Global Health program is trying to do.

When I worked at Microsoft, it was always a thrill to see a product we’d been working on for years finally get released to the public. I’m feeling the same sense of anticipation today. My new book on climate change is available now online and in bookstores.

I wrote How to Avoid a Climate Disaster because I think we’re at a crucial moment. I’ve seen exciting progress in the more than 15 years that I’ve been learning about energy and climate change. The cost of renewable energy from the sun and wind has dropped dramatically. There’s more public support for taking big steps to avoid a climate disaster than ever before. And governments and companies around the world are setting ambitious goals for reducing emissions.

What we need now is a plan that turns all this momentum into practical steps to achieve our big goals. That’s what How to Avoid a Climate Disaster is: a plan for eliminating greenhouse gas emissions.

I kept the jargon to a minimum because I wanted the book to be accessible to everyone who cares about this issue. I didn’t assume that readers know anything about energy or climate change, though if you do, I hope it will deepen your understanding of this incredibly complex topic. I also included ways in which everyone can contribute—whether you’re a political leader, an entrepreneur, an inventor, a voter, or an individual who wants to know how you can help.

The effort I founded called Breakthrough Energy, which started with a venture fund to invest in promising clean energy companies, has expanded to a network of philanthropic programs, investment funds, and advocacy efforts to accelerate energy innovation at every step. We’ll be supporting great thinkers and cutting-edge technologies and businesses, as well as pushing for public- and private-sector policies that will speed up the clean energy transition. Over the coming weeks and months, we’ll be turning the ideas in my book into action and trying to turn this plan into reality.

Below is an excerpt from the introduction, which gives you a sense of what the book is about and how I came to write it. I hope you’ll check out the book, but much more important, I hope you’ll do what you can to help us keep the planet livable for generations to come.

Excerpt from How to Avoid a Climate Disaster

Two decades ago, I would never have predicted that one day I would be talking in public about climate change, much less writing a book about it. My background is in software, not climate science, and these days my full-time job is working with my wife, Melinda, at the Gates Foundation, where we are super-focused on global health, development, and U.S. education.

I came to focus on climate change in an indirect way—through the problem of energy poverty.

In the early 2000s, when our foundation was just starting out, I began traveling to low-income countries in sub-Saharan Africa and South Asia so I could learn more about child mortality, HIV, and the other big problems we were working on. But my mind was not always on diseases. I would fly into major cities, look out the win­dow, and think, Why is it so dark out there? Where are all the lights I’d see if this were New York, Paris, or Beijing?

I learned that about a billion people didn’t have reliable access to electricity and that half of them lived in sub-Saharan Africa. (The picture has improved a bit since then; today roughly 860 million people don’t have electricity.) I began to think about how the world could make energy affordable and reliable for the poor. It didn’t make sense for our foundation to take on this huge problem—we needed it to stay focused on its core mission—but I started kick­ing around ideas with some inventor friends of mine.

In late 2006 I met with two former Microsoft colleagues who were starting nonprofits focused on energy and climate. They brought along two climate scientists who were well versed in the issues, and the four of them showed me the data connecting greenhouse gas emissions to climate change.

I knew that greenhouse gases were making the temperature rise, but I had assumed that there were cyclical variations or other fac­tors that would naturally prevent a true climate disaster. And it was hard to accept that as long as humans kept emitting any amount of greenhouse gases, temperatures would keep going up.

I went back to the group several times with follow-up questions. Eventually it sank in. The world needs to provide more energy so the poorest can thrive, but we need to provide that energy without releasing any more greenhouse gases.

Now the problem seemed even harder. It wasn’t enough to deliver cheap, reliable energy for the poor. It also had to be clean.

Within a few years, I had become convinced of three things:

1. To avoid a climate disaster, we have to get to zero greenhouse gas emissions.
2. We need to deploy the tools we already have, like solar and wind, faster and smarter.
3. And we need to create and roll out breakthrough technologies that can take us the rest of the way.

The case for zero was, and is, rock solid. Setting a goal to only reduce our emissions—but not eliminate them—won’t do it. The only sensible goal is zero.

This book suggests a way forward, a series of steps we can take to give ourselves the best chance to avoid a climate disaster. It breaks down into five parts:

Why zero? In chapter 1, I’ll explain more about why we need to get to zero, including what we know (and what we don’t) about how rising temperatures will affect people around the world.

The bad news: Getting to zero will be really hard. Because every plan to achieve anything starts with a realistic assessment of the barriers that stand in your way, in chapter 2 we’ll take a moment to consider the challenges we’re up against.

How to have an informed conversation about climate change. In chapter 3, I’ll cut through some of the confusing statistics you might have heard and share the handful of questions I keep in mind in every conversation I have about climate change. They have kept me from going wrong more times than I can count, and I hope they will do the same for you.

The good news: We can do it. In chapters 4 through 9, I’ll break down the areas where today’s technology can help and where we need breakthroughs. This will be the longest part of the book, because there’s so much to cover. We have some solutions we need to deploy in a big way now, and we also need a lot of innovations to be developed and spread around the world in the next few decades.

Steps we can take now. I wrote this book because I see not just the problem of climate change; I also see an opportunity to solve it. That’s not pie-in-the-sky optimism. We already have two of the three things you need to accomplish any major undertaking. First, we have ambition, thanks to the passion of a growing global move­ment led by young people who are deeply concerned about climate change. Second, we have big goals for solving the problem as more national and local leaders around the world commit to doing their part.

Now we need the third component: a concrete plan to achieve our goals.

Just as our ambitions have been driven by an appreciation for climate science, any practical plan for reducing emissions has to be driven by other disciplines: physics, chemistry, biology, engineering, political science, economics, finance, and more. So in the final chap­ters of this book, I’ll propose a plan based on guidance I’ve gotten from experts in all these disciplines. In chapters 10 and 11, I’ll focus on policies that governments can adopt; in chapter 12, I’ll suggest steps that each of us can take to help the world get to zero. Whether you’re a government leader, an entrepreneur, or a voter with a busy life and too little free time (or all of the above), there are things you can do to help avoid a climate disaster.

That’s it. Let’s get started.

In 1999, a Microsoft colleague named Paul Flessner approached me with a personal request: Would I be willing to help fund the development of new drugs for cystic fibrosis, an awful lung disease that affects about 30,000 people—including more than 10,000 children—in the U.S. and about 70,000 people worldwide?

Ten years after the discovery of the gene implicated in CF, researchers still had not produced any medical breakthroughs for CF patients, and Paul was concerned that time was running short for his sons. So he asked me to support an effort by a small startup called Aurora Biosciences to screen up to 10,000 chemical compounds a day in an effort to find ones that might help CF patients; at the time, typical screening methods allowed for testing just a few chemical compounds a day.

The whole project was untried and risky. But my dad, who was helping Melinda and me with our early philanthropic efforts, and I reasoned that philanthropists should be willing to take big risks like this, and so we decided to provide $20 million of the $47 million needed to launch this research project.

This pathbreaking work led, over two decades, to several very effective CF medicines, including drugs marketed with the names Kalydeco, Orkambi, and Trikafta. For many CF patients, these medicines produce the kind of miraculous “Lazarus effect” that I would see when I visited with AIDS patients taking cocktails of antiretroviral medicines. In fact, Paul recently sent me a video of one of his sons, a software engineer in his early 30s, running at an altitude of 7,500 feet. “For both boys, it’s like not having CF anymore,” he wrote. “Since Trikafta, one of the boys has stopped taking all of the antibiotics he used to control infections and stopped all airway-clearance therapy. It is a huge new liberty for him.”

Through Paul, I’ve been able to follow the big milestones in this success story. But now, thanks to a new book called Breath from Salt, I understand a lot more about all the people who made these breakthroughs possible, including many thousands of physicians, scientists, statisticians, engineers, patients, advocates, donors, and entrepreneurs.

Breath from Salt is not for everyone. It’s long and sometimes feels overly detailed; I suspect the author, Bijal P. Trivedi, felt obliged to include all of the people she interviewed, even if they played minor roles. But given my interest in the process of discovery and my connection to this specific effort, I couldn’t put the book down.

The book is reminiscent of Tracy Kidder’s 1981 book Soul of a New Machine, which documents the creation of a powerful new computer, because Trivedi leads you on a tour through the ups and downs of the discovery process. She gives it life-and-death urgency and emotion. In fact, I was surprised to learn that she doesn’t have a family connection to CF.

Among the heroes Trivedi profiles is the O’Donnell family, who live near Boston. In 1974, Kathy and Joe O’Donnell had their first child, Joey. Unfortunately, Joey inherited CF mutations from both of his parents, which meant he got the disease. Like all CF patients, Joey could not produce healthy copies of the protein we all need to maintain the balance of salt and water on surfaces in our bodies, such as the surface of the lung. That meant his tiny lungs would fill with thick, sticky mucus, reducing his lung capacity and making him highly susceptible to dangerous infections.

Joe and Kathy knew that many CF patients didn’t make it past adolescence. But they simply would not give up on Joey. They found outstanding healthcare providers, spent months on end in hospitals, and dedicated hours of every day to clapping on Joey’s chest to help free mucus from his airway. Even with Kathy and Joe’s significant resources, their son died at age 12.

Joe, who had grown up in a tough neighborhood but had gone on to become a very successful businessman, found purpose in leading huge fundraising campaigns to spur CF drug discovery. Without his own financial contributions, fundraising prowess, and business acumen, there’s no way that CF patients would have the treatments they have today. Joe helped raise money for drugs that would have worked for his son, but the book makes it clear that that wasn’t his motivation. He did it for all children with CF.

The second hero of this story is the Cystic Fibrosis Foundation and its three generations of leaders. Given that CF is an orphan disease that affects only a small slice of the population, it’s remarkable to me that this organization grew to become one of the biggest and most powerful players among disease-research charities. I was impressed by the courage of the foundation leaders who made the controversial decision to place almost all their chips on scientific research and to build sophisticated patient registries to facilitate clinical trials. I also admired the creative “venture philanthropy” approaches the CF Foundation used to fund drug discovery.

The third group of heroes is the CF researchers who kept building the knowledge necessary to produce these drugs, such as the San Diego-based team that started with Aurora and now work for a company called Vertex. Breath from Salt shows us their passion for their work, the ways they fought to protect it even when it wasn’t paying financial dividends, and the remarkable scientific breakthroughs they pioneered.

It was touching to learn about emotional moments in the process, such as when Fred Van Goor, one of the leaders of the San Diego team, heard the results of the clinical trial on the drug combination he’d helped to create. “Hearing how the patients’ lungs responded to this new medicine, how dramatically it opened them up, made [him weep]. Van Goor was unprepared for the pent-up emotions that had been swirling in him for the past 18 years, and for how desperately he’d wanted those treatments to work.”

The final group of heroes are compassionate caregivers, including parents, who fought to keep CF children alive when they had few tools for doing so. This list includes not just senior physicians like Joey’s doctor at Massachusetts General Hospital but also unsung heroes like a physical therapist who grew very close to Joey and so many other children while working with them every day to help them keep their lungs as healthy as possible.

Breath from Salt is an inspiring book. It’s a testament to what’s possible when passionate leaders help to harness the unique strengths of philanthropy, nonprofits, government, academia, biotechs, big pharma, and medical providers. Given the remarkable pace of innovation in the biosciences, I know there will be more success stories like this in the coming years.

My dad’s mom, Lillian Gates, was lucky to have survived the 1918 influenza pandemic. Unlike COVID-19, which is hitting older people the hardest, the influenza pandemic caused the highest mortality among people in their twenties. The most vulnerable of all were pregnant women. In 1918, my grandmother was 27 and pregnant with my dad’s older sister. She was living in Bremerton, WA, which suffered big losses from influenza because it had a big Navy shipyard and sailors coming from all over the world.

Then as now people isolated themselves at home, streets were empty, and industry shut down. Doctors and nurses were incredibly heroic, putting their own lives at risk and working themselves to the bone. The best parts of human nature were frequently on display—but so were acts of ignorance, greed, and fear of the “other.”

To refresh my memory about the realities and lessons of that devastating pandemic, I recently reread The Great Influenza (2004), by John M. Barry. He does a great job of showing just how profoundly that pandemic affected not just millions of families like mine but also the entire flow of history.

Barry speculates that if not for the pandemic, World War II might never have erupted. In 1918, when President Woodrow Wilson was in the midst of negotiating with his British and French counterparts the treaty to end World War I, he got a violent case of the flu. He survived, but he was never the same again, physically or mentally. Previously, Wilson had insisted that the treaty must represent “peace without victory” and would not give in to the harsh terms French President Georges Clemenceau wanted to impose on the Germans. But after getting the flu, Wilson “yielded to Clemenceau everything of significance Clemenceau wanted,” Barry writes.

No one can know for sure what effect the flu really had on Wilson, or what the effect of a gentler Treaty of Versailles might have been. But Barry is sure that Wilson’s illness contributed to the rise of Hitler: “Historians with virtual unanimity agree that the harshness towardGermany of the Paris peace treaty helped create the economic hardship, nationalistic reaction, and political chaos that fostered the rise of Adolf Hitler.”

When The Great Influenza first came out, I got a copy from Bill Foege, a good friend and public-health hero who helped to eradicate smallpox. I’m glad I read it. It’s one of several books that made it clear to me that the world needed to do a better job of preparing for novel pathogens. Writing roughly 16 years ago, Barry was clear and persuasive that “another pandemic not only can happen…. It almost certainly will happen.”

I wasn’t the only one who took Barry’s admonition to heart. As ABC recently reported, “President George W. Bush was on vacation at his ranch in Crawford, Texas, when he began flipping through a … copy of a new book about the 1918 flu pandemic [given to him by Health Secretary Mike Leavitt]. He couldn’t put it down.” Bush and Leavitt then worked to pass a multi-billion-dollar pandemic-preparation bill.

So what are the big lessons from the 1918 influenza pandemic?

First and foremost, leadership matters. Scientific leaders like Army Surgeon General William Gorgas stepped up. And so did some, but by no means all, governors and mayors. In St. Louis, for example, the city mobilized quickly and staged effective responses that saved many lives. In Philadelphia, in contrast, the mayor ignored the advice of experts that he should cancel a massive parade in support of the war effort. A few days later, the bodies started piling up. “Undertakers, themselves sick, were overwhelmed. They had no place to put bodies…. Undertakers’ work areas were overflowing, they stacked caskets in halls, in their living quarters,” writes Barry.

Second, truth matters. In 1918, America’s political leaders—even health commissioners—sugarcoated bad news to avoid panicking the public. That greatly undermined their authority when citizens saw friends and neighbors dying in great numbers. Barry concludes that “those in authority must retain the public’s trust. The way to do that is to distort nothing, to put the best face on nothing, to try to manipulate no one.”

Third, philanthropy has an important role to play. In fact, things could have been much worse if not for the gifts of John D. Rockefeller, Johns Hopkins, and many other donors. These gifts fundamentally transformed American science and medicine in the late 19^thth and early 20 centuries giving the country hundreds of thousands of well-trained professionals to treat those who fell ill from influenza and guide the public-health response.

Fourth, pandemics are humbling. Despite the brilliant work at the Rockefeller Institute, Johns Hopkins University, and other institutions, doctors never had the benefit of effective antiviral medications or a vaccine. In fact, it was not until 1933 that scientists confirmed that it was a virus, rather than a bacterium, that caused the influenza pandemic.

This time around, we have many more tools at our disposal for creating effective vaccines and therapeutics. But the science is still slower than any of us would like, and putting an end to this pandemic will require more than just great science. It will also take a lot of political will, especially encouraging social distancing and making sure that scientific miracles spread as far and wide as the virus itself.

When Melinda and I first started learning about childhood vaccines, we were appalled to learn that it often took decades for a new vaccine to be put to widespread use in the developing world. So even before we have all the tools we need to defeat COVID-19, my colleagues at the Gates Foundation, Gavi, and many other organizations are working to raise the money, organize the institutions, and develop a global plan of action for distributing them around the globe. In 1918, the world just didn’t have the systems to do that. Melinda and I are deeply committed to making sure we will this time around.

Back in my early Microsoft days, I routinely pulled all-nighters when we had to deliver a piece of software. Once or twice, I stayed up two nights in a row. I knew I wasn’t as sharp when I was operating mostly on caffeine and adrenaline, but I was obsessed with my work, and I felt that sleeping a lot was lazy.

Now that I’ve read Matthew Walker’s Why We Sleep, I realize that my all-nighters, combined with almost never getting eight hours of sleep, took a big toll. The book was recommended to me by my daughter Jenn and John Doerr. Walker, the director of UC Berkeley’s Center for Human Sleep Science, explains how neglecting sleep undercuts your creativity, problem solving, decision-making, learning, memory, heart health, brain health, mental health, emotional well-being, immune system, and even your life span. “The decimation of sleep throughout industrialized nations is having a catastrophic impact,” Walker writes.

I don’t necessarily buy into all of Walker’s reporting, such as the strong link he claims between not getting enough sleep and developing Alzheimer’s. In an effort to wake us all up to the harm of sleeping too little, he sometimes reports as fact what science has not yet clearly demonstrated. But even if you apply a mild discount factor, Why We Sleep is an important and fascinating book.

Because this is a short review, I’ll answer a few questions that I suspect are top of mind for you.

Does everyone really need seven or eight hours of sleep a night?The answer is that you almost certainly do, even if you’ve convinced yourself otherwise. In the words of Dr. Thomas Roth, of the Henry Ford Hospital in Detroit, “The number of people who can survive on five hours of sleep or less without impairment, and rounded to a whole number, is zero.”

Why do we sleep?After all, when you’re sleeping—and all animals do—you can’t hunt, gather, eat, reproduce, or defend yourself. Yet Walker concludes that the evolutionary upsides of sleep are far greater than these downsides. In brief, sleep produces complex neurochemical baths that improve our brains in various ways. And it “restocks the armory of our immune system, helping fight malignancy, preventing infection, and warding off all manner of sickness.” In other words, sleep greatly enhances our evolutionary fitness—just in ways we can’t see.

What can I do to improve my sleep hygiene?

• Replace any LEDs bulbs in your bedroom, because they emit the most sleep-corroding blue light.
• If you’re fortunate enough to be able to control the temperature where you live, set your bedroom to drop to 65 degrees at the time you intend to go to sleep. “To successfully initiate sleep … your core temperature needs to decrease by 2 to 3 degrees Fahrenheit,” according to Walker.
• Limit alcohol, because alcohol is not a sleep aid, contrary to popular belief. While it might help induce sleep, “alcohol is one of the most powerful suppressors of REM [rapid-eye-movement] sleep,” Walker says.
• If you can possibly take a short midday nap like our ancestors used to and some Mediterranean and South American cultures still do, you should (but no later than 3 pm). It will likely improve your creativity and coronary health as well as extend your lifetime.

It took me a little longer than usual to finish Why We Sleep—ironically, because I kept following Walker’s advice to put down the book I was reading a bit earlier than I was used to, so I could get a better night’s sleep. But Walker taught me a lot about this basic activity that every person on Earth needs. I suspect his book will do the same for you.

After astronaut Rusty Schweickart looked down on Earth from space for the first time, he described a sense of awe that has become common to almost every space traveler since: “You realize that on that little blue and white thing there is everything that means anything to you, all history and music and poetry and art and death and birth and love, all of it on that little spot out there you can cover with your thumb.” NASA calls this realization “the overview effect.” No matter what country you’re from, you return from space with a feeling that our home is tiny, fragile, and something we need to protect.

Anyone who reads the new book Growth, the newest of 39 brilliant books by one of my favorite thinkers, will come away with similar urgency. The author, the Czech-Canadian professor Vaclav Smil, approaches things from a scientist’s point of view, not an astronaut’s, but he reaches the same conclusion: Earth is fragile and “before it is too late, we should embark in earnest on the most fundamental existential [task] of making any future growth compatible with the long-term preservation of the only biosphere we have.”

Before I get into how Smil came to this conclusion, I should warn you. Although Growth is a brilliant synthesis of everything we can learn from patterns of growth in the natural and human-made world, it’s not for everyone. Long sections read like a textbook or engineering manual. (“A plot of the annual totals of passenger-kilometers flown by all US airlines between 1930 and 1980 produces a trajectory that is almost perfectly captured by the quartic regression (fourth order polynomial with r²=0.9998), and continuation of this growth pattern would have multiplied the 1980 level almost 10 times by 2015.”) And it has 99 pages of references!

As Smil writes, “My aim is to illuminate varieties of growth in evolutionary and historical perspectives and hence to appreciate both the accomplishments and the limits of growth in modern civilization... Simply put, this book deals in realities as it sets the growth of everything into long-term evolutionary and historical perspectives and does so in rigorous quantitative terms.”

When Smil says “the growth of everything,” he means everything. Chapter 1 introduces a lot of technical detail behind the three most common growth curves seen in our natural and built environments: linear, exponential, and hyperbolic. Even if you don’t like math, don’t let this chapter scare you off, because it makes a really important point: It destroys the idea that you can take an early growth curve for a particular development—the uptake of the smartphone, for example—and use it as the basis for predicting the future. Yes, Intel co-founder Gordon Moore made a surprisingly accurate prediction about the exponential growth in the number of transistors on a chip. But even that “law” is likely reaching the end of its useful life. Transistors are now so small, we’re running into problems making them even smaller.

The next few chapters are easier to follow. Chapter 2 is all about the growth of living systems—from microorganisms to sequoia forests, and from humans to dinosaurs. (By the way, did you know that the T. rex weighed only a bit more than a male African elephant, and a tapeworm can live 25 years?) My favorite part of this chapter was Smil’s discussion of food production, which is instructive for our foundation’s work in agriculture and does a good job of explaining what kinds of productivity gains are possible.

In chapter 3, he lands on a topic he knows better than just about anyone else: the development and diffusion of new sources of energy—from traditional water wheels to nuclear reactors. He has covered a lot of this terrain in previous books such as his masterful Energy and Civilization. But here he’s setting the stage for subsequent chapters on technological developments that were made possible by the conversion of resources like water, wind, carbon, and solar radiation into energy.

When I read chapters 4 (artifacts, such as cathedrals, cars, and computers) and 5 (societies and economies), I had to marvel over how Smil’s mind works. The way he synthesizes information from dozens of different domains is amazing. I also marveled over all the miracles that modern civilization is built on, including power grids, water systems, air transportation, and computing. The book gave me new appreciation for how many smart people had to try things out, make mistakes, and eventually succeed.

Smil’s goal for these chapters is to show that no matter what domain you’re talking about, eventually you hit growth limits. Steel, the backbone of modern economies, is a great example. After many years of metallurgical and mechanical innovation, we’re simply not able to make it a lot cheaper or with a lot less energy. Ultimately, his analysis shows that what we’re trying to do in terms of changing our physical economy and the energy flows upon which it is built would be unprecedented in our history.

In chapter 6 and in a brief coda, Smil sounds less like an academic than an activist. He concludes that “treating the biosphere as a mere assembly… of goods and services to be exploited (and used as a dumping ground) with impunity—must change in radical ways.”

I don’t agree with all of his analysis. In particular, I’m more optimistic than he is about the degree to which today’s renewable energy technologies can be deployed, and the pace at which scientists and engineers will develop new clean sources. In my view, Smil underestimates our accelerating ability to model the physical world using digital technologies equipped with artificial intelligence. For example, future generations of clean energy will be designed and tested in computers, not on paper, before we try them in the world—a process that will speed up innovation in a dramatic way.

But I’ve always felt that Smil’s great strength isn’t predicting the future, it’s documenting the past. There’s great value in that—you can’t see what’s coming next if you don’t understand what’s come before. Nobody sees the big picture with as wide an aperture as Vaclav Smil.

Last year I highly recommended Bad Blood, about the rise and fall of the Silicon Valley blood-diagnostics company Theranos and its founder, Elizabeth Holmes. Since then, I watched the HBO documentary The Inventor, which covers the same story.

I’m not alone in my interest. A lot of my friends and colleagues have read the book, watched the movie, or listened to a podcast called The Dropout. I think part of people’s fascination with the Theranos story has to do with the drama of it all. But personally, I’m also interested in the topic of blood and diagnostic tools that involve blood. I recently started making investments in blood tests that would help detect Alzheimer’s disease years or even decades before disease symptoms show up. I’m also involved with a company that’s trying to speed up the search for blood tests that can detect cancers.

With this context in mind, you can understand why I decided to pick up the book Nine Pints: A Journey Through the Money, Medicine, and Mysteries of Blood. (The title refers to the volume of blood in the average adult.)

The author, an English nonfiction writer named Rose George, is interested in blood because of her own life story. She has a debilitating condition called premenstrual dysphoric disorder, which I knew very little about. Before George gets her period every month, PMDD causes her to writhe on the floor in pain and gives her such dark thoughts that she has to “avoid a nearby road bridge because I don’t have the defenses to stop myself from jumping off it.” The treatments for PMDD are terribly inadequate, in large part because there’s been so little funding for research (especially compared to conditions that primarily affect men).

Nine Pints takes George all around the world. For example, she visits a plasma clinic in Saskatoon, Canada; an HIV clinic in the South African township of Khayelitsha; a rural Nepalese village where menstruating women are relegated to unheated sheds; and Indian communities benefitting from the work of an entrepreneur named Arunachalam Muruganantham, who developed a technique for manufacturing cheap sanitary pads for poor women. (I had a great time speaking on a panel with him a few years ago.)

The book is packed with super-interesting facts that I had to work very hard not to share with unsuspecting friends and colleagues during social occasions. For example:

• The Nazis’ ideology gave the Allies a surprising advantage: An unknown number of Nazi soldiers died of survivable wounds simply because Nazi doctors wouldn’t use “non-Aryan blood” for transfusions.
• Trade in human and animal blood is worth more than $20 billion a year. Blood, which costs the equivalent of $67,000 a barrel, is the 13th-most-traded commodity in the world.
• The blood flow in the modern human brain is 600 percent greater than it was in early humans.

Even if these kinds of strange facts don’t capture your imagination, I suspect many of George’s stories will. Some of them will make your blood boil. For example, George writes about girls in poor countries having sex with older men simply so they can afford pads and tampons. “It’s called ‘sex for pads,’ and though it is hidden, it is common,” she writes, citing a report from a field officer in one African slum that 50 percent of the girls she encountered there had turned to prostitution to afford sanitary pads.

But I don’t want to leave you with the impression that the book is all doom and gloom. Many aspects of the book were uplifting, especially the parts that reminded me of the life-saving innovations that emerge from a better understanding of blood and its component parts. Blood tests have already made it easier and faster to diagnose diseases and predict when a pregnant woman will deliver her baby.

In the future, I hope we’ll find more ways to harness substances in our blood to reduce inflammation and promote healing. I’m particularly optimistic about the new ways we’re using immune cells in the blood to fight cancer. I also hope that stimulating the immune cells in our blood could eventually allow us to do a better job of attacking the proteins that have been implicated in Alzheimer’s, Parkinson’s, and other neurodegenerative diseases.

Nine Pints may not sound like a typical light summer book. But George is a great reporter and writer who makes it easy to follow along. And I think everyone wants to know at least a little more about this topic. After all, there is nothing that more people have in common than blood.

I don’t read a lot of page turners. I often find myself unable to put a book down—but they’re not the kinds of books that would keep most people glued to their chairs. Still, I recently found myself reading a book so compelling that I couldn’t turn away.

Bad Blood: Secrets and Lies in a Silicon Valley Startup by John Carreyrou details the rise and fall of Theranos. If you aren’t familiar with the Theranos story, here’s the short version: the company promised to quickly give you a complete picture of your health using only a small amount of blood. Elizabeth Holmes founded it when she was just 19 years old, and both she and Theranos quickly became the darlings of Silicon Valley. She gave massively popular TED talks and appeared on the covers of Forbes and Fortune.

By 2013, Theranos was valued at nearly $10 billion and even partnered with Walgreens to put their blood tests in stores around the country. The problem? Their technology never worked. It never came close to working. But Holmes was so good at selling her vision that she wasn’t stopped until after real patients were using the company’s “tests” to make decisions about their health. She and her former business partner are now facing potential jail time on fraud charges, and Theranos officially shut down in August.

The public didn’t know about Theranos’ deception until Carreyrou broke the story as a reporter at the Wall Street Journal. Because he was so integral to the company’s demise, Bad Blood offers a remarkable inside look.

Some of the details he shares are—for lack of a better word—insane. Holmes would invite prospective investors to the lab, so they could get their blood tested on a Theranos machine. The device had been programmed to show a really slow progress bar instead of an error message. When results didn’t come back right away, Holmes sent the investors home and promised to follow up with results.

As soon as they left, an employee would remove the blood sample from the device and transfer it to a commercial blood analyzer. Her investors got their blood tested by the same machines available in any lab in the country, and they had no idea.

There’s a lot Silicon Valley can learn from the Theranos mess. To start, a company needs relevant experts on its board of directors. The Theranos board had some heavy hitters—including several former Cabinet secretaries and senators—but for most of the company’s existence, none of them had any expertise in diagnostics. If they had, they might have noticed the red flags a lot sooner.

Health technology requires a different approach than other kinds of technology, because human lives are on the line. Carreyrou writes a lot about how Holmes idolized Steve Jobs and his unwillingness to compromise on his vision. That approach is okay for consumer electronics—if a new phone doesn’t work as promised, no one gets hurt—but it’s irresponsible for a health company. Holmes pushed a vision of what Theranos could be, not what it actually was, and people suffered as a result.

Bad Blood is also a cautionary tale about the virtues of celebrity. On the surface, Holmes was everything Silicon Valley loves in a CEO: charismatic and convincing with a memorable personal story made for magazine profiles. There’s nothing wrong with that on its own. A rock star CEO can be a huge boon for a startup. But you can’t let fame become the most important thing.

Theranos is the worst-case scenario of what happens when a CEO prioritizes personal legacy above all else—but I hope that people don’t use it as an excuse to write off the next young woman with a big idea. I also don’t want Bad Blood to scare people away from next-gen diagnostics. Theranos went to extraordinary lengths to get around quality standards. The industry is highly regulated, and new diagnostics undergo rigorous testing.

Bad Blood tackles some serious ethical questions, but it is ultimately a thriller with a tragic ending. It’s a fun read full of bizarre details that will make you gasp out loud. The story almost feels too ridiculous to be real at points (no wonder Hollywood is already planning to turn it into a movie). I think it’s the perfect book to read by the fire this winter.

As regular TGN readers know, I’m a fan of Vaclav Smil, a Czech-Canadian professor emeritus at the University of Manitoba. I’ve read nearly all of his 37 books. I wait for new Smil books the way some people wait for the next Star Wars movie. Some years I don’t have to wait long. In 2013 alone, Smil published four!

I read Smil because he’s uniquely good at going both deep and broad. Many writers who come out of academia specialize in delving deep into a topic they’ve studied for years, but they typically don’t bring together insights from across many different disciplines. Many impressive writers who come from journalism are the opposite. They’re great at painting the big picture, but they’re not as well equipped to depict the fine details. Smil can do both with equal facility.

In his latest book, Energy and Civilization: A History, he goes deep and broad to explain how innovations in humans’ ability to turn energy into heat, light, and motion have been a driving force behind our cultural and economic progress over the past 10,000 years. Yes, our history has a lot to do with kings and queens and games of thrones. Smil shows that it has even more to do with energy innovation.

Here’s Smil’s thesis in a nutshell: Once groups of humans graduated from hunting and gathering and learned how to cultivate crops in ways that would produce more food than they needed for their own survival, they had the time and energy to use their brains in new ways. They applied that brainpower to getting even more efficient at converting energy into food—using animal power, tools, crop rotation, fertilizers, irrigation, and new seed varieties. The gains in crop production led directly to higher population densities. This, in turn, led to more complex societies and greater specialization of work, and an incredible array of advances in every area of human endeavor.

The past 300 years have seen the most miraculous advances in the human condition—and just about all of those advances can be traced directly to the exploitation of new forms of energy. Smil takes you through these advances in painstaking detail. For example, he shows that the biggest transition in the human condition started in the mid-18^th century, after ironmasters in Europe began firing their furnaces with metallurgical coke, made from low-ash, low-sulfur coal. Coke-fueled furnaces could be much larger than charcoal (wood) furnaces and drove an increase in global production from 800,000 tons in 1750 to 30 million tons in 1900. A series of additional metallurgical innovations in the late 1800s led to the modern steel industry, which has provided the most important material for industrial development ever since.

With the help of original calculations and some good explanatory illustrations, Smil describes the other energy-related innovations that drove rapid economic growth and quality-of-life improvements—as well as profound environmental degradation—in the 19^thth and 20 centuries. While many of the innovations will be familiar to you, you will undoubtedly learn new things about the steam engine, internal combustion engines running on gasoline, the generation of electricity, the transformer (“it made inexpensive, centralized electricity generation possible [and] would probably win a contest for a device that is as common and indispensible for the modern world as it is absent from the public consciousness”), and renewables.

As usual with Smil, he doesn’t overstate or oversimplify his case. He’s well aware that energy is not the only way to view the advance of humanity – things like morality play crucial roles too. “Energy is not the only determinant of … life in general and human actions in particular…. [It is] among the most important factors shaping a society, but [it does] not determine the particulars of its successes or failures.”

I’ll admit that Energy and Civilization is not easy reading. In fact, when I read my first Smil books years ago, I felt a little beat up and asked myself, “Am I ever going to be able to understand all of this?” But follows an easy chronological progression and is well edited.

The best way to give you a sense of the book is to share some of the remarkable facts Smil digs up. As you’ll see, they range over many different academic fields. They are not the kind of things you could simply pull off Wikipedia. They often involve original calculations that only Smil would do.

• Gathering roots was a super efficient strategy for foraging groups. “As many as 30-40 units of food energy were acquired for every unit expended. In contrast, many hunting forays, above all those for smaller arboreal or ground mammals in tropical rain forests, had a net energy loss or bare equivalence.”
• It’s fascinating to reflect on how much energy innovation occurred during the course of a single century. “When in 1900 a Great Plains farmer held the reins of six large horses while plowing his wheat field, he controlled … no more than 5 kW of animate power. A century later his great-grandson, sitting high above the ground in the air-conditioned comfort of his tractor cabin, controlled effortlessly more than 250 kW of diesel engine power.”
• We waste a tremendous amount of food. “The food supply in affluent countries is now 75% higher than actual need, resulting in enormous food waste (30-40% of all food at the retail level).”

Throughout every section of the book, Smil makes a clear case that energy consumption and economic growth are inextricably linked. In his words, “to become rich requires a substantial increase in energy use.” I fully agree with him. And in the past century or so, the biggest increase in energy use has come from fossil fuels—which are expensive and drive climate change. That’s why I’m spending a lot of my time and resources trying to accelerate research and development to make clean energy less expensive than fossil fuels, and just as reliable.

The main disagreement I have with Smil is about how quickly we can make the transition to clean energy. He is absolutely right that Moore’s Law and the speedy advances in software have misled people into thinking all innovation and adoption happens that quickly. Yet I am more optimistic than he is about the prospects of speeding up the process when it comes to clean energy.

Perhaps it’s the insights I have gained from my work with Breakthrough Energy Ventures (a fund that’s investing more than $1 billion in clean-energy innovation), what I’ve learned from experts connected with ARPA-E, or the research I see going on in the labs of the world’s top energy innovators. When I learn about their efforts, I can’t help but feel optimistic about what’s on the horizon—from carbon-neutral liquid fuels to game-changing improvements in energy generation, storage, and transmission.

Smil told me that his next book is going to be about growth—everything from crops and babies to empires and economies. The truth is, I’d read just about any topic he found interesting and wanted to dissect. But growth sounds like a perfect topic for him. I’m looking forward to it already.

The year Melinda and I started our foundation, President Bill Clinton convened in the White House some of the world’s great scientists to announce a huge milestone for humanity. Two rival efforts, one led by the National Institutes of Health and the other by a private company, had completed the first draft of the human genome map. “Without a doubt,” Clinton said, “this is the most important, most wondrous map ever produced by humankind.”

Fast forward 16 years. With little public fanfare, geneticists have reached another super important milestone. While the human genome map gave us the ability to read all three billion letters of our genetic code, we now have the power to edit the human genome as well. Thanks in part to a chance discovery by researchers working to improve yogurt, scientists can now enter human cells, selectively snip out sections of code, and then incorporate new sequences permanently in the genome.

Scientists have now launched early-stage clinical trials with these new genome-editing tools. These tools are generating a ton of optimism for diagnosing, treating, and curing human disease. Even before researchers successfully complete clinical trials in humans, genome editing will be put to good use in modifying plants and animals—all of which holds big promise for our foundation’s work to alleviate hunger and improve health in poor countries.

Although I am excited about these advances, we have to approach them with caution. It’s one thing to reprogram the code that runs our computers. Reprogramming the code that runs our species is a very different thing altogether.

As with any powerful new technology, genome editing will be attractive to people with both good intentions (reducing human suffering) and bad (causing it). Even just with respect to the former, the ethical questions are enormous.

That is why I am so glad I read The Gene: An Intimate History, by Columbia University cancer doctor and researcher Siddhartha Mukherjee and recently had a chance to chat with him in person. He is the perfect person to guide us through the past, present, and future of genome science.

I loved Mukherjee’s 2015 TED Talk and his brilliant book about cancer, The Emperor of All Maladies, which won the Pulitzer Prize in 2011. It must really tick off full-time writers that a doctor can win a Pulitzer in his spare time!

In The Gene, Mukherjee once again shows his gift for making hard science easily accessible. He wrote this book for general audiences, because he knows that it’s not good enough for scientists alone to debate the huge ethical questions that their discoveries provoke. As he emphasized repeatedly in our conversation, determining the proper rules and boundaries for these technologies requires broad public discussion, debate, and consensus.

Mukherjee makes The Gene accessible in a variety of ways. Like all good science writers, he offers creative metaphors to explain difficult concepts. He is also a beautiful storyteller. He uses that talent to weave in his own family’s history of mental illness, which I found incredibly touching.  And through stories, he introduces us to the key pioneers in genetics—from Gregor Mendel, who repeatedly failed the exam to teach high school science but later ushered in the modern science of genetics, to Francis Collins, the devout Christian motorcycle enthusiast who brilliantly led the public effort to sequence the human genome.  

My favorite part of the book was the final section, “Post-Genome: The Genetics of Fate and Future.” It does a great job bringing into sharp focus the difficult ethical questions that will become increasingly intense.

Within 10 years, it will be possible for clinicians to use genome editing to help people with diseases caused by a single faulty gene, such as cystic fibrosis—an unquestionably ethical use of this new technology. But what about making the repair in egg or sperm cells to save people from developing these diseases later in life? This form of therapy could be highly effective, but it would mean that children born from these sperm or eggs would pass along their genetically modified genomes to their own children—altering the human germ line and crossing an ethical Rubicon.

Altering the human germ line is not just a hypothetical possibility. Teams of researchers in China are racing to do so in human embryos. While these researchers are using non-viable embryos, a Swedish developmental biologist recently announced that he is editing healthy, viable human embryos. He says he will not let the edited embryos develop past 14 days, but there’s no telling what other scientists may be planning. “By the time this book is published … the first ‘post-genomic’ human might be on his or her way to being born,” Mukherjee reports.

As I read The Gene, I came up with long lists of ethical questions of my own. For example, what if a prenatal test told you with a high degree of certainty that your child will have an IQ of 80 unless you do this little edit? What if a private IVF clinic offered its patients a little enhancement to their fertilized embryos to boost children’s likely IQ from high to very high? This could exacerbate inequities that are already a big problem—especially if this technology is available only for wealthy people. What about a series of edits that could dramatically reduce the incidence of disorders on the autism spectrum? Wouldn’t that mean reducing human diversity in dangerous ways—perhaps even eliminating the possibility of a future Alan Turing, the brilliant computer pioneer who helped break Germany’s Enigma code during World War II?

Technology is amoral. It is neither good nor bad. It is up to all of us—not just scientists, government officials, and people fortunate enough to lead foundations—to think hard about these new technologies and how they should and should not be used. Reading The Gene will get you the point where you can actively engage in that debate.

I’ve been perpetuating a misconception.

When I give talks about global health, I typically speak about microbes as threats we need to wipe off the map. And it’s certainly true that some microbes, like the ones that cause malaria and tuberculosis, are responsible for tremendous suffering and death around the world. But the view that microbes always equal disease and are essentially bad things is an oversimplification.

I’m seeing microbes with new eyes and talking about them in different terms thanks to British journalist Ed Yong. After reading his super-interesting book I Contain Multitudes, I had a chance to chat with him in person about his view that “microbes are mostly not to be feared or destroyed but to be cherished, admired, and studied.”

In I Contain Multitudes, Yong synthesizes literally hundreds and hundreds of papers, but he never overwhelms you with the science. He just keeps imparting one surprising, fascinating insight after the next. I Contain Multitudes is science journalism at its best.

Yong makes clear that only a tiny fraction of microbes have the ability to make us sick. There are approximately 100 species of bacteria that cause infectious disease in humans. But there are hundreds of thousands of species that live peacefully, symbiotically within us, primarily in our gut. Microbes help us digest our food, break down toxins, guide our physical development, protect us from disease, and even speed human evolution. We are utterly dependent on them.

We are also utterly inseparable from them. Yong illustrates that we are at least as much microbe as human. We literally have more microbial cells living inside our bodies than human cells. And even the cells we label “human” are part microbe. With the exception of red blood cells and sperm, all our cells are powered by mitochondria, which are likely the descendants of ancient bacteria that became integrated into the type of cells that subsequently gave rise to all complex life. (The story of how that happened is the subject of another book I loved: The Vital Question, by the biologist Nick Lane.)

I found some of Yong’s reporting directly relevant to my role as a parent. Melinda and I—and most parents in the U.S. and other rich countries—have dramatically cut down on our children’s exposure to the diverse array of microbes that for millennia have helped human beings strengthen their immune systems and avoid inflammatory diseases. As Yong puts it, “We have been tilting at microbes for too long, and created a world that is hostile to the ones we need.”

It’s not just all the anti-bacterial soaps and sanitizers we Americans use. Another major problem is the excessive use of antibiotics. On net, antibiotics have been unbelievably positive for humanity. But every time we give them, we are carpet-bombing our microbial ecosystem (microbiome), not merely knocking out pathogens. “A rich, thriving microbiome acts as a barrier to invasive pathogens,” writes Yong. “When our old friends vanish, that barrier disappears [and] more dangerous species can exploit the … ecological vacancies.”

As you can imagine, the book is also quite relevant to my work at our foundation, especially in the area of children’s growth and development. Yong explains why, if we want to prevent malnutrition, we not only need to help alleviate hunger and provide key micronutrients. We will also need to learn why some kids’ microbiomes are out of balance and how to restore them back to a healthy state.

Not only could this lead to low-cost interventions for malnutrition. I suspect this line of research will also help scientists make inroads against many other diseases. The list of disorders that have been linked to disruptions in the microbiome includes Crohn’s disease, ulcerative colitis, irritable bowel syndrome, colon cancer, obesity, type 1 diabetes, type 2 diabetes, and Parkinson’s disease. Even though we don’t have good ways of manipulating the microbiome to head off disease, I am hopeful we will eventually. I’m particularly excited about the implications for neurodegenerative diseases like Parkinson’s. It may turn out that these diseases get their start in the gut a decade or more before any brain symptoms show up. If that’s the case, the gut may prove to be a great target for medicines, giving new hope to many millions of families.

Another area of intense interest for Yong and for me is harnessing benign microbes to fight dangerous ones. Our foundation has been supporting some cutting-edge work to infect certain species of mosquitoes with a very common bacterium called Wolbachia to make it impossible for these mosquitoes to spread a painful, debilitating disease called dengue fever.

As Yong reports, this approach worked wonders in its first field trial, in eastern Australia. In just four months, Wolbachia-infected mosquitoes almost totally replaced the mosquitoes capable of carrying the virus that causes dengue—effectively wiping out dengue in the region. (I had a chance to see and report on this work on a visit to Indonesia, in 2014.) The implications of these tests are huge. We believe that Wolbachia could also be effective at stopping the spread of other viruses, such as Chikungunya and Zika. This approach might also have the potential to be a powerful tool in the fight against malaria.

In the end, I Contain Multitudes is a healthy corrective. Yong succeeds in his intention to give us a “grander view of life” and does so without falling prey to grand, unifying explanations that are far too simplistic. He presents our inner ecosystems in all their wondrous messiness and complexity. And he offers realistic optimism that our growing knowledge of the human microbiome will lead to great new opportunities for enhancing our health.

All lives have equal value. But some deaths seem particularly cruel.

When Paul Kalanithi was diagnosed with terminal cancer in 2013, he was a 36-year-old on the verge of making big contributions to the world with his mind and hands. He was a gifted doctor—a chief resident in neurosurgery at Stanford just months away from completing the most grueling training of any clinical field. He was also a brilliant scientist. His postdoctoral research on gene therapy won him his field’s highest research award.

As if that wasn’t enough, he was also a great writer. Before attending medical school, he earned two degrees in English literature from Stanford and gave serious consideration to pursuing writing as a full-time career.

What a talent. What a loss.

I know about Kalanithi’s story because he told it himself in the posthumous When Breath Becomes Air. It’s an amazing book. I was super touched by it, as was Melinda and our daughter Jennifer. In fact, I can say this is the best nonfiction story I’ve read in a long time.

Thanks to this book, the reader gets to know well and like Kalanithi a lot. He brings you not just into his journey as a doctor and then as a patient but also into his role as a husband, which was sorely strained at times by the rigors of his and his wife’s clinical residencies. My emotional investment got particularly strong after Kalanithi and his wife, Lucy, decide to have a child despite (or maybe even because of) Kalanithi’s diagnosis. Kalanithi was there for the delivery, but he was so weak and chilled from chemotherapy that he wasn’t able to put his newborn daughter against his skin. Eight months later, Kalanithi died a few hundred yards away from where his daughter entered the world.

I’m usually not one for tear-jerkers about death and dying—I didn’t love The Last Lecture or Tuesdays with Morrie. But this book definitely earned my admiration—and tears.

I don’t know how anyone could read Lucy’s epilogue, in particular, without choking up. “I visit his grave often, taking a small bottle of Madeira, the wine of our honeymoon destination,” she writes. “Each time, I pour some out on the grass for Paul … and rub the grass as if it were Paul’s hair. Cady visits his grave before her nap, lying on a blanket … grabbing at the flowers we’ve laid down.”

But don’t be put off by the sadness of it all. I should emphasize the other things that drew me to this book.

For one thing, I thoroughly enjoyed Kalanithi’s stories about his surgical training. I’ve always admired doctors. They have to make impossibly hard decisions, and so much of their work has life-and-death implications. Kalanithi illustrates these high stakes well, without sounding like he has a God complex. One story that will stick with every parent who reads this book involves a young patient with a brain tumor. “The difference between tragedy and triumph was defined by one or two millimeters. One day, Matthew, … who had charmed the ward a few years back, was readmitted. His hypothalamus had … been slightly damaged during the operation to remove his tumor; the adorable eight-year-old was now a twelve-year-old monster.”

I was also drawn in by Kalanithi’s eloquent writing. I look up to all doctors, but the ones I’m impressed with most are the ones who are not just gifted healers but also writers. It’s always a shock to me when I find one, but by now it shouldn’t be. Kalanithi is part of a fraternity of amazing writer doctors, including Abraham Verghese (who wrote the foreword to Paul’s book), Siddhartha Mukherjee, and Atul Gawande. Perhaps I should consult a neuroscientist to figure out whether these seemingly disparate talents are somehow linked in the brain.

I am certain I will read When Breath Becomes Air again. This short book has so many layers of meaning and so many interesting juxtapositions—life and death, patient and doctor, son and father, work and family, faith and reason—I know I’ll pick up more insights the second time around.

I don’t know how Kalanithi found the physical strength to write this book while he was so debilitated by the disease and then potent chemotherapy. But I’m so glad he did. He spent his whole brief life searching for meaning in one way or another—through books, writing, medicine, surgery, and science. I’m grateful that, by reading this book, I got to witness a small part of that journey.

I just wish the journey hadn’t been cut so short.

Last year Trevor Mundel, who runs our foundation’s global health work, suggested that I read a book called The Vital Question. I had never heard of the book or its author, a biologist at University College London named Nick Lane. A few months later, I hadn’t just read —I had also ordered Nick’s three other books, read two of them, and arranged to meet him in New York City.

Nick reminds me of writers like Jared Diamond, people who develop a grand theory that explains a lot about the world. He is one of those original thinkers who makes you say: More people should know about this guy’s work.

At its heart, Nick’s work is an attempt to right a scientific wrong by getting people to fully appreciate the role that energy plays in all living things. The Vital Question begins with a bang: “There is a black hole at the heart of biology.”(I wish more science books got off to such a ripping start.) “Bluntly put, we do not know why life is the way it is. All complex life on earth shares a common ancestor, a cell that arose from simple bacterial progenitors on just one occasion in 4 billion years. Was this a freak accident, or did other ‘experiments’ in the evolution of complexity fail?” Why does all complex life—every plant and animal you can see—share certain traits, like getting old and reproducing via sex? Why didn’t different types of complex life evolve? And if there is life on other planets, would it necessarily have these same traits? Or could E.T. reproduce by cloning himself?

Nick argues that we can only start to answer these questions by fully appreciating the role of energy.

In a way, he’s putting a different spin on an issue I’ve been writing a lot about lately. I’ve been talking about how getting energy right at the global level—developing affordable, reliable sources of clean energy—will help us fight poverty and climate change. Nick is talking about how getting energy right at the cellular level explains how life began, and how it got so complex.

Early on in The Vital Question, he explores the latest thinking about the origin of life. Bacteria and another type of single-celled organism called archaea seem to have developed about 4 billion years ago, thanks to an energy differential in alkaline vents deep in the ocean. Nick’s account of how that happened is thrilling. He builds on the work of others, adding his own research, and explains it in a way that is so compelling that it’s hard to imagine any other way. It’s not what most of us learned in school—there is no primordial soup involved—and it’s a gripping tale.

For the next two billion years, bacteria and archaea were the only forms of life of Earth. Then an exceptionally rare thing happened. A bacterium worked its way inside an archaeon and survived. The bacterium became an endosymbiont, one living thing inside another, each benefiting from something offered by the other.

This merging of cells had probably happened before and since, but it is always highly unlikely to succeed. Most of the time, both cells die. “The one occasion where it really worked out,” Nick says, “is what led to us.”

How? The bacterium contributed some of its genes to what became the nucleus of the cell. The leftovers became mitochondria, which act as tiny power plants for every form of complex life we know about. And they are one of the key things that differentiate us from bacteria and archaea.

Here’s one reason why. Simple cells like bacteria generate all their energy in their outer membrane, which puts a physical limit on how big they can get and still make enough energy to support themselves. (In mathematical terms, their volume expands faster than their surface area, so their demand for energy eventually exceeds their ability to generate it.) Once cells had internalized the means of making energy—that is, once they had mitochondria—this constraint disappeared. Mitochondria also have specialized genomes focused on energy generation, but bacteria don’t. So cells with mitochondria could get much bigger, allowing for complex new arrangements.

In The Vital Question, Nick goes on to show how energy can help explain why life is the way it is. He makes a persuasive case that complex life must have the traits we see today. And he argues that it would almost certainly develop the same way everywhere. Which means that, if we find complex life on other planets, it will quite likely share the same traits. In other words, E.T. can’t clone himself. If he wants to have kids, he’ll need Mrs. E.T.

Back on Earth, I’m intrigued by the practical applications of Nick’s work. Mitochondria could play a role in diseases like cancer. In addition, our foundation’s global health team is talking to Nick about the potential implications for the fight against malnutrition.

Nick has a very scientific demeanor. In reading his books and talking to him, I never got the impression that he was claiming more than he should or trying to pull a fast one on the reader. It’s always clear where he’s citing someone else’s work and where he’s building out his own ideas. And he would be the first to tell you that some of his ideas might be wrong.  

As much as I loved The Vital Question, it’s not for everyone. Some of the explanations are pretty technical. But this is a technical subject, and I doubt anyone else will make it much easier to understand without sacrificing crucial details. He uses lots of vivid metaphors to explain key ideas. Every few pages he sums up what he has just said and recaps the important points. If you have a scientific bent and you remember a bit of chemistry and biology, you should find The Vital Question quite approachable.

If you’re going to read this book, do it relatively soon. Five years from now, Nick and the other researchers in this field will have gotten a lot further. Of course, there’s no telling whether his specific arguments will turn out to be right. But even if they don’t, I suspect his focus on energy will be seen as an important contribution to our understanding of where we come from, and where are we going.

Last week in Paris I got to be part of a big announcement about energy and climate. Several governments and private investors came together to make major commitments for funding clean-energy research. This is a big focus for me, because providing more energy for the poor is essential for fighting poverty, and because switching to clean energy is essential for stopping climate change.

But energy is not the only factor that affects how much carbon we pump into the atmosphere. I recently read an excellent book about another key factor: how we make stuff. The book is called Sustainable Materials With Both Eyes Open, by a team at the University of Cambridge led by researchers Julian Allwood and Jonathan Cullen. (You can download it free on their site.) Although the book is probably too detailed for most general readers—its 350 pages are filled with dense diagrams and a lot of numbers—the authors’ conclusions are well worth understanding.

They focus on the five materials that account for more than half of the world’s industrial carbon emissions (steel, cement, paper, plastic, and aluminum). As I’ve mentioned before, it’s impossible to imagine a modern world without these materials. Every year for example we produce more than 440 pounds of steel for every person on Earth, nearly half of which goes into buildings. And demand for all these materials will roughly double by 2050, as the world’s population grows and more people join the global middle class. Yet producing this stuff contributes significantly to climate change—and also creates other risks like reducing the supply of drinkable water and land that could be used for growing food.

The question boils down to this: How can we meet the growing demand for materials without destroying the environment?

The authors start by asking whether we can get a big enough reduction in greenhouse gases simply by producing these materials more efficiently. (They’re looking for a 50 percent reduction. I think we need to get to at least 80 percent by 2050 and eventually 100 percent, but either way you’re talking about a big cut.) Unfortunately, efficiency gains on their own won’t be enough. The problem is that demand is going to double by mid-century. Suppose you make widgets, and you invent a way to cut your carbon emissions by 30 percent per widget. If you start making twice as many widgets, your overall emissions will still go up by 40 percent. The authors call this approach—thinking only about efficiency gains—looking “with one eye open.”

How do you look with both eyes open? By also studying how you could use less material to begin with, make products that last longer, reuse or recycle them, or avoid using the service the material provides. The authors argue that by looking with both eyes open—both using less stuff, and making stuff more efficiently—it should be possible to cut emissions in half without asking people to make big sacrifices.

I was surprised to learn how many opportunities there are to reduce overall use of materials. For example, although I knew about basic recycling efforts like collecting aluminum cans at the office, I hadn’t realized how much reuse is possible at an industrial level. The authors argue that when a product—say, a building or car—is discarded, the materials in it are often still usable. (Reusing is much better than recycling, because recycling takes yet more energy.) If you throw out your old refrigerator, the steel is probably still in good condition. So is the steel in old buildings, as long as there hasn’t been a fire or earthquake. It could be reused, if you could take it apart easily and get it to someone who wanted that shape.

But matching up buyers and sellers is hard. Who has the time to look around for someone who might want pieces of your old refrigerator? This is an area where technology can help. We can put digital stamps on products so we can track their history, and digital markets can match supply with demand. There are other intriguing ideas too, like finding ways to make buildings that are dismantled instead of demolished, so we could reuse more of the stuff they’re made of.

Although the book isn’t aimed at a general audience, the authors keep things lively with colorful illustrations and funny analogies. I’ve read other books about steel, but none of them featured a photo of the Carhenge exhibit in Nebraska. I’ve read a lot of books about physics, but I don’t remember seeing such an extended riff on how atoms act like people dancing in a nightclub.

The book’s message is clear and convincing: We can’t go on using materials the way we have been for the past 150 years, but fortunately, we don’t have to. We can meet the world’s growing need for the stuff of modern life, avoid the worst effects of climate change, and preserve the environment for future generations.

I don’t remember the first time I heard of smallpox, but when I was a kid in Seattle in the 1960s it wasn’t exactly top of mind for my friends and me. I’m sure I heard about it when the World Health Organization announced in 1980 that smallpox had been eradicated, but I still didn’t pay much attention. After all, smallpox had been eradicated in the United States for almost a century; it’s hard to get too worked up about a disease that nobody you know has ever gotten. It wasn’t until later, when our foundation joined global eradication efforts, that I really started thinking about what it takes to wipe a disease from the face of the earth. Most people think it’s incredibly difficult. It turns out, it’s much harder than that.

That’s why I enjoyed Nancy Leys Stepan’s book Eradication: Ridding the World of Diseases Forever?. It gives you a good sense of how involved the effort to eradicate a disease can get , how many different kinds of approaches have been tried without success, and how much we’ve learned from our failures.

To illustrate the history of eradication, she focuses on the career of Fred Soper, who led efforts to eradicate yellow fever, typhus, and malaria, first at the Rockefeller Foundation and then, from 1947 to 1959, as director of the Pan-American Health Organization.

I’m a little more positive on Soper than Stepan is, but the view she gives of him is very balanced. He got a lot done, but he did it by being extremely demanding, both in his eradication methods and in his dealings with people, and that made him both very effective in some ways and very difficult to deal with. He reportedly tried to strangle somebody who disagreed with him in a meeting. Despite his faults, though, without Soper, I don’t know that we would have eradicated smallpox or that we would be on the verge of eradicating polio.

Soper’s biggest mistake—and on this I agree with Stepan—was believing that scientists had already learned everything there was to learn about mosquitoes and malaria. Because of that he spent a lot of time and money—and made life harder for a lot of people—trying to eradicate a disease that actually was not understood well enough. Scientists didn’t have enough of the right data. Soper didn’t have a deep enough understanding of human behavior and international politics. And most of all, he didn’t doubt himself enough. I think we’re approaching all these issues in better ways today, and I remain optimistic about the world’s strategy to get rid of malaria for good.

I feel similarly optimistic about the effort to eradicate polio. Although it has taken longer and cost more than we thought it would, there are now only two countries that have never been polio-free—Afghanistan and Pakistan—and we're on the verge of eradicating it entirely. Once that happens, we’ll be able to use the infrastructures we’ve set up for taking on other diseases.

I do disagree with some of Stepan’s arguments. For example she faults eradication programs for not strengthening health infrastructures—she writes that they can come “at the expense of a broader approach to ill health.” In theory, they can—but more and more, they don’t. The systems being put in place to deal with polio are actually strengthening health systems more broadly. Part of the reason Nigeria was able to contain Ebola during the recent outbreak was that polio workers there were able to step in to help with the response. Without them, the country's 180 million citizens would have been at far greater risk; in fact, in countries without the polio-eradication infrastructure, the outbreak was much worse.

Finally, a word of warning: Eradication is written in a very academic style, and it may be a challenge for non-experts to get to Stepan’s valuable arguments. It’s worth the effort, though, because you come away from it with a clearer sense of what the world has learned about getting rid of diseases and how we can use that to guide the effort to save even more lives.

Terminology is an occupational hazard of philanthropy. I’ve found this is especially true if you work in an area like health. It is not unusual to be discussing the latest disease research and hear someone throw around words like serum and in vitro (and more complicated ones). Over the years I’ve gotten comfortable with all the terms, but at first I had to keep reminding myself: Serum just means blood without the red and white cells. In vitro just means “in the glass”—as in test tubes. I still go through that process today with different subjects.

So it was fun to read Randall Munroe’s new book, Thing Explainer: Complicated Stuff in Simple Words, which will come out on November 24. Munroe sets out to explain various subjects—from how smartphones work to what the U.S. Constitution says—without any complicated terms. Instead he draws blueprint-style diagrams and annotates them using only the 1,000 most common words in the English language. A nuclear reactor is a “heavy metal power building.” A dishwasher is a “box that cleans food holders.” The periodic table is “the pieces everything is made of.”

It is a brilliant concept. If you can’t explain something simply, you don’t really understand it. And Randall Munroe is the perfect guy to take on a project like this. He’s a former NASA robotics expert who nowmakes a living drawing the geeky comic strip XKCD and writing books. (I reviewed his What If? earlier this year.) Munroe reminds me of Sal Khan of Khan Academy, or the novelist and Crash Course host John Green. All three are polymaths who not only know a lot but are also good at breaking things down for other people.

Thing Explainer may use a limited vocabulary, but it is filled with helpful explanations and drawings. Have you ever wondered why frozen food defrosts unevenly in a microwave oven (or, as Munroe calls it, a “food-heating radio box”)? Munroe writes: “When you put iced food in a radio box, after a while, parts of it start to turn to water. But since radio boxes are really good at heating water, those parts start to get hot really fast. They can even get so hot they start turning to air—before all the ice is even gone!”

If you know Munroe’s previous work, it will come as no surprise that parts of Thing Explainer are laugh-out-loud funny. Here for example is what he says about the business end of a Saturn V rocket (“U.S. Space Team’s Up Goer Five”): “Lots of fire comes out here. This end should point toward the ground if you want to go to space. If it starts pointing toward space you are having a bad problem, and you will not go to space today.”

Or, his take on the 18^th amendment to the U.S. Constitution: “Let’s get rid of beer and wine.” And then the 21^st: “Never mind about getting rid of beer and wine.”

If I have a criticism of Thing Explainer, it’s that the clever concept sometimes gets in the way of clarity. Occasionally I found myself wishing that Munroe had allowed himself a few more terms—“Mars” instead of “red world,” or “helium” instead of “funny voice air.”

Of course, that would defeat the purpose of the book. And Munroe himself is aware of the tension. In “Page Before the Book Starts”—a.k.a. the introduction—he acknowledges that some terminology is inescapable. “To really learn about things, you need help from other people, and if you want to understand those people, you need to know what they mean by the words they use. You also need to know what things are called so you can ask questions about them. But there are lots of other books that explain what things are called. This book explains what they do.”

And it does that beautifully. Thing Explainer is filled with cool basic knowledge about how the world works. If one of Munroe’s drawings inspires you to go learn more about a subject—including a few extra terms—then he will have done his job. He has written a wonderful guide for curious minds.

The first time I met Chris Murray, he was wrestling with a big question. It was in the early 2000s, and Chris was working at the World Health Organization in Geneva. I was in town for some meetings at the WHO and heard from Chris about a project he was working on. He wanted to understand: Why do people get sick and die?

It wasn’t a philosophical question. He meant, What are the biggest causes of death and disability? How does HIV compare with strokes or road injuries or suicide or back injuries? How do the answers change over time and in different countries?

As Chris would explain a few years later: “Nobody would imagine starting out on a long journey without knowing where they're going and what route they would take. Yet, if you look at global health, that was where the world was—huge ignorance about what people died from.”

Chris told me he wanted to create a comprehensive database that would answer those questions, and make it available free online. It was obviously a big challenge, both scientifically and politically. But I thought that if he could pull it off, it would be a fantastic tool for everyone who cares about these issues. And it became clear that Chris—a compassionate scientist with a love for hard data and software—was the right person to take it on.

Chris went on to spend a few years on the faculty at Harvard University; when he left in 2007, I jumped at the chance to help bring him to the University of Washington, where he set up the Institute for Health Metrics and Evaluation. A few years later, Chris and his team launched the project he had been dreaming of: a comprehensive update of the Global Burden of Disease, or GBD, using data from researchers around the world. They also built some very cool data visualizations with the information and analysis from the GBD.

Chris’s story is told well in Jeremy Smith’s book Epic Measures: One Doctor. Seven Billion Patients, which came out earlier this year. It’s a highly readable account for anyone who wants to know more about Chris’s work and why it matters. As Smith says, it is “the story of a huge independent effort, years in preparation, to do nothing less than chart everything that threatens the health of everyone on Earth, and make that information publicly available to doctors, health officials, political leaders, and private citizens everywhere.”

I visit the GBD data visualizations a few times each month. It takes a while to get good at finding your way around the tools, but once you do, they are amazingly informative. There are more than a billion entries in the database, covering several hundred causes of death and disease. Recently Melinda and I were trying to understand suicide rates in different countries—and how they differ among men and women—and we quickly found the information we were looking for. (It turns out that in some countries the male/female gap is more than 5 to 1, while in others it is more like 1 to 1.)

The idea behind Chris’s work is simple: We can’t cure what we don’t understand. If we know what the biggest killers are, we can make sure our efforts to save lives are aimed at the right things. And we can learn what works. In this TGN post you can watch Chris use the GBD to explain how setting goals and measuring progress has helped drive huge gains in health—which is one reason I’m optimistic about the new Global Goals being adopted this month at the United Nations. (Melinda and I will be there to help spread the word about the goals.)

What I love most about the GBD is the way it democratizes information. Much of the data was available previously, but it was scattered around the world—buried in various countries’ databases and in printed reports that gathered dust on office shelves. The GBD brings it all together, synthesizes it, and makes it available to everyone. Thanks to input from experts around the world, it keeps getting more accurate. It is slowly becoming the standard go-to resource for health data in rich and poor countries alike.

Epic Measures gives you a good sense of why all this is so important. Smith writes, “With a truly all-encompassing view of life and death, we can see for the first time if Europe is healthier than America, or Iowa than Ohio, or you than your neighbor. And then in what ways. And how people are responding, with specific details everyone else around the world can try to emulate.”

I agree—and I would add that the GBD is another example of how technology is making it easier to save and improve lives everywhere. As Epic Measures shows, the more we make sure reliable information gets out there, the better decisions we all can make, and the more impact we all can have.

People have all kinds of obsessions—silly, serious, and everything in between. The sheer diversity of these fascinations, from playing bridge (my personal obsession) to scanning the skies for new planets, is one of the most beautiful things about humanity. And yet one person’s obsession doesn’t necessarily make for interesting reading for those of us who have never been bitten by that same bug.

Mark Miodownik’s personal and professional obsession, as he explains in his book Stuff Matters, is basic materials we often take for granted such as paper, glass, concrete, and steel—as well as new super-materials that will change our world in the decades ahead. I’m pleased to report that he is a witty, smart writer who has a great talent for imparting his love of this subject. As a result, is a fun, accessible read.

My favorite writer, the historian Vaclav Smil, also wrote a wonderful book on materials, but it’s completely different from Miodownik’s. Smil is a facts-and-numbers guy; he doesn’t bring any romance to his topic. Miodownik is the polar opposite. He’s heavy on romance and very light on numbers.

Miodownik, an Oxford-trained materials scientist who has worked in some of the most advanced labs in the world, discovered his obsession with materials in a bizarre way. When he was in high school in the 1980s, he was the victim of a random attack on a London Tube train. In his telling, instead of freaking out about the five-inch slash wound in his back, he fixated on the elegance of the attacker’s steel razor blade. “This tiny piece of steel, not much bigger than a postage stamp, had cut through five layers of my clothes, and then through the epidermis and dermis of my skin in one slash without any problem at all,” he writes. “It was the birth of my obsession with materials.”

Most of us have the luxury of not thinking much about steel—and not being attacked with a razor. But as Miodownik makes clear, steel is pretty magical. Its greatest virtue is that it doesn’t crack or break under tension, unlike iron, from which it is forged. Steel has been made by skilled blacksmiths dating back to ancient Roman times, but once inventors created a process for producing steel cheaply at industrial scale in the mid 19^th century, it became central to our lives—from our utensils to our transport to our built environment.

Our next century is likely to produce even bigger material innovations. I live close to the longest floating bridge in the world, which, like so many big modern structures, is made from steel-reinforced concrete. That bridge has served Seattle well for more than a half century, but now it’s near the end of its lifespan. (From my yard I can see the construction crews working on the bridge that will replace it.) According to Miodownik, future bridges may be built with a “self-healing concrete” that could save billions of dollars in repair and replacement costs. 

Self-healing concrete is a great study in material innovation. In highly sulfurous volcanic lakes that would burn human skin, scientists found incredibly resilient bacteria that can stay dormant in rock for decades. You embed these bacteria in concrete with starch for them to consume; when the concrete cracks and water starts seeping in, the bacteria revive, find the starch, begin to replicate, and excrete minerals that seal up the crack.

I particularly liked Miodownik’s informative chapter on carbon (“Unbreakable”), which offers insights into one atom’s massive past, present, and future role in human life. Diamonds, one of the many material manifestations of carbon, have played a starring role in love and war for millennia. Coal powered our transition into the industrial age and is having significant impact on the chemistry of our atmosphere. Carbon fiber composites, sheets of graphite fibers encased in epoxy glues, are now transforming major industries from sports to aerospace to automobiles. I recently was briefed on carbon fiber city buses purchased by the city of Seattle, which are much lighter, stronger, cleaner, and safer than traditional steel buses and will save the city a lot of money on fuel.

Then there are far more exotic forms of carbon—like graphene, a layer of graphite one atom thick, and carbon nanotubes, graphene’s rolled-up form. Graphene is the thinnest and stiffest material known to humankind—200 times stronger than steel and yet lighter than paper. It is also the best conductor ever invented. As a result, it may someday replace the silicon chip and help usher in a new era in computing and communications. Yes, stuff matters!

In political contests, voters sometimes put more weight on whether they’d like to have a beer with a candidate than on the candidate’s qualifications. Miodownik would pass anyone’s beer test, and he has serious qualifications. I’ll be interested to see what he writes next. 

Have you caught any episodes of Cosmos, featuring the astrophysicist Neil deGrasse Tyson? If you haven’t, you should. The show, an update to Carl Sagan’s classic 1980 series, aired a year ago and is available on a variety of streaming services. Recently I’ve been watching the series on DVD.

You don’t have to be a kid to get a lot out of this series. In science, we’re all kids. A good scientist is somebody who has redeveloped from scratch many times the chain of reasoning of how we know what we know, just to see where there are holes. So it can never hurt to revisit great scientific explanations like the ones Tyson shares. They help bolster your confidence in what you understand about how the world works. They help you consolidate your knowledge of how insights from physics, chemistry, and biology all fit together. They help you see science as approachable and not just endlessly complicated.

The Cosmos production team, which includes Sagan’s wife, clearly understands this. They did a great job of bringing the wonders of space and time to people with different levels of knowledge. And Tyson’s lifelong passion for scientific discovery comes through loud and clear.

Richard Dawkins, the evolutionary biologist who held the Chair of Public Understanding of Science at Oxford University endowed by my friend Charles Simonyi, has a similar gift for making science enjoyable. I’ve read many of his books over the years, including The Selfish Gene and The Blind Watchmaker. His antagonistic (and, to me, overzealous) view of religion has earned him a lot of angry critics, but I consider him to be one of the great scientific writer/explainers of all time.

I recently had a chance to read his book The Magic of Reality: How We Know What’s Really True. The book is as accessible as Cosmos is for younger audiences—and as relevant for older audiences. It’s an engaging, well-illustrated science textbook offering compelling answers to big questions, from how the universe formed to what causes earthquakes. It’s also a plea for readers of all ages to approach mysteries with rigor and curiosity, rather than buying into the supernatural myths at the core of most faith traditions.

Fortunately, Dawkins’s love of scientific exploration comes through more than his antipathy toward religion. He organizes each chapter around a question (e.g., “What is the sun?”) and begins the chapter with a litany of colorful explanatory myths offered by different cultures around the world. Then he shows us the elegant answers science has offered as the power of direct and indirect detection has expanded through the years. “I hope you agree that the truth has a magic of its own,” he writes. “The truth is more magical—in the best and most exciting sense of the word—than any myth or made-up mystery or miracle.”

I have only two disappointments about this book. First, I wish Dawkins had carved out the space to address some of the trickier areas of science like quantum mechanics, which really is fundamental to our understanding of the physical world and is at the core of many of our modern technologies.

Second, it’s too bad that some people may not read this book because of Dawkins’s strong views on religion. Even if Dawkins’s tone here is less contentious than usual, I fear this won’t get too far beyond the choir (to use a metaphor Dawkins might not appreciate). That’s too bad.

If The Magic of Reality appeals to you, you might also check out the online course Big History (which I helped fund). It’s similar to Dawkins’s book in that they both set out to give you a comprehensive view—a framework for understanding how knowledge fits together—and then you can dive into different areas that interest you. It’s a great way to start or continue your learning journey, no matter how old you are.

My guess is that you haven’t spent a whole lot of time wondering what would happen if you pitched a baseball at 90 percent of the speed of light. I haven’t either.

But that’s okay, because Randall Munroe has figured it out and explained it really clearly in his book What If?.

It’s a collection of some of his favorite posts from one of the two blogs he keeps. His first blog, XKCD, which he’s also turned into a book, is made up of cartoons he draws making fun of things—mostly scientists and computers, but lots of other things too. There’s one about scientists holding a press conference to reveal their discovery that life is arsenic-based. They research press conferences and find out that sometimes it’s good to serve food that’s related to the subject of the conference. The last panel is all the reporters dead on the floor because they ate arsenic. It’s that kind of humor, which not everybody loves, but I do.

What If? may not be quite as funny as XKCD, but it’s a lot more interesting. The subtitle of the book is “Serious Scientific Answers to Absurd Hypothetical Questions,” and that’s exactly what it is. People write Munroe with questions that range over all fields of science: physics, chemistry, biology. Questions like, “From what height would you need to drop a steak for it to be cooked when it hit the ground?” The answer, it turns out, is “high enough that it would disintegrate before it hit the ground.” Another question: “What would happen if you made a periodic table out of cube-shaped bricks, where each brick was made of the corresponding element?” to which the answer is, essentially, the human race would be wiped out. Munroe’s explanations are funny, too—he’ll use giraffes as a unit of height measurement, and draw pictures of ten giraffes standing on top of each other.

Nevertheless, the explanations are scientifically valid. And they’re very well researched, with citations of obscure papers like “Sexual Cannibalism in Orb-Weaving Spiders: An Economic Model” (actually, that one is from the website, but I assume it’ll make it into the sequel, which I hope will be called What Iffer. Or the next one, What If? Strikes Back). He verifies his facts by calling expert scientists all over the world, and I have to imagine those conversations are amazing.

The reason Munroe’s approach is a great way to learn about science is that he takes ideas that everybody understands in a general way and then explores what happens when you take those ideas to their limits. For example, we all know pretty much what gravity is. But what if Earth’s gravity were twice as strong as it is? What if it were three times as strong, or a hundred? Looking at the question in that way makes you start to think about gravity a little differently.

Here’s another example. It turns out that, if you have a glass that’s literally half empty—the top half water and the bottom half a perfect vacuum—the glass shatters and the pieces fly up to the ceiling. But Munroe doesn’t just say, “the glass shatters.” He goes through every step of the process, so that you understand why the glass shatters. The suction squeezing together the glass and the water—which, by the way, is boiling—is so powerful that it actually lifts the glass off the table. When the glass and the water finally meet, the water is moving downward quickly enough that the shock breaks the bottom of the glass. Meanwhile, the glass is moving upward quickly enough that the broken pieces fly up to the ceiling. Munroe concludes: “If the optimist says the glass is half full, and the pessimist says the glass is half empty, the physicist ducks.”

So if you’re dying to know how fast you can drive over a speed bump and still live, or how many Legos it would take to build a bridge from London to New York, or whether we could make the moon change colors by pointing every single laser pointer on Earth at it—you’re in luck. Not only do you have a place to go for the answers, but you’ll also learn about a lot of other things like ballistics, DNA, the oceans, the atmosphere, and lightning. And when to duck if the glass is half full.

This is one of two Randall Munroe books I’ve read, and it is (by design) the funnier of the pair. It’s a collection of posts from his blog XKCD, which is made up of cartoons he draws making fun of things—mostly scientists and computers, but lots of other things too. There’s one about scientists holding a press conference to reveal their discovery that life is arsenic-based. They research press conferences and find out that sometimes it’s good to serve food that’s related to the subject of the conference. The last panel is all the reporters dead on the floor because they ate arsenic. It’s that kind of humor, which not everybody loves, but I do.

Here’s my review of the other Munroe book I’ve read, What If?, where he takes absurd queries (“From what height would you need to drop a steak for it to be cooked when it hit the ground?”) and uses them to explain scientific ideas. He doesn’t crack quite as many jokes as in XKCD, but it is very informative. You’ll learn about things like ballistics, DNA, the oceans, the atmosphere, and lightning.

In my late twenties I went vegetarian for a year. Some of my friends were strict non-meat-eaters, and I wanted to try it out. Plus I was flying a lot for work and found that the airplane meals made with tomatoes and beans just tasted better than the shoe-leather beef. In the end, though, I couldn’t keep it going, and I eventually returned to my carnivorous ways.

Years later, I came to realize that it was a luxury for me to spurn meat. In most places, as people earn more money, they want to eat more meat. Brazil’s per-capita consumption has gone up fourfold since 1950. China’s nearly doubled in the 1990s. Mexico, Indonesia, South Korea, and Japan have also seen big increases. 

More countries are sure to follow, and that’s a good thing. Meat is a great source of high-quality proteins that help children fully develop mentally and physically. In fact part of our foundation’s health strategy involves getting more meat, dairy, and eggs into the diets of children in Africa.

But there’s also a problem. Raising animals can take a big toll on the environment. You have to feed the animal far more calories than you extract when you eat it. It’s especially problematic as we convert large swaths of land from crops that feed people to crops that feed cows and pigs. Plus clearing forests to make more farmland contributes to climate change, as do the greenhouse gases produced by all those animals.

The richer the world gets, the more meat it eats; the more meat it eats, the bigger the threat to the planet. How do we square this circle?

I can’t think of anyone better equipped to present a clear-eyed analysis of this subject than Vaclav Smil. I have written several times before about how much I admire Smil’s work. When he tackles a subject, he doesn’t look at just one piece of it. He examines every angle. Even if I don’t agree with all of his conclusions, I always learn a lot from reading him.

That is certainly true of his book Should We Eat Meat?. He starts by trying to define meat (it’s surprisingly slippery—do you count kangaroos? crickets?), then explores its role in human evolution, various countries’ annual consumption (the United States leads the way with roughly 117 kilograms of carcass weight per person), and the health and environmental risks. He also touches on ethical questions about raising animals for slaughter and covers some simple ways to eliminate the needless cruelty involved.

As usual, Smil offers up some intriguing statistics along the way. A quarter of all ice-free land in the world is used for grazing livestock. Every year, the average meat-eating American ingests more than enough blood to fill a soda can. And Americans eat a lot of pepperoni: 

Another thing Smil loves to do is question the conventional wisdom. For example, you may have read that raising meat for food requires a lot of water. This has been in the news lately because of the drought in California. Estimates vary, but the consensus is that between watering the animals, cleaning up after them, and growing crops to feed them (far and away the biggest use), it takes several thousand liters of water to produce one kilogram of boneless beef.

But Smil shows you how the picture is more complicated. It turns out that not all water is created equal. Nearly 90 percent of the water needed for livestock production is what’s called green water, used to grow grass and such. In most places, all but a tiny fraction of green water comes from rain, and because most green water eventually evaporates back into the atmosphere, it’s not really consumed.

As Smil writes, “the same water molecules that were a part of producing Midwestern corn to feed pigs in Iowa may help to grow, just a few hours later, soybeans in Illinois… or, a week later, grass grazed by beef cattle in Wales.” One study that excluded green water found that it takes just 44 liters—not thousands—to produce a kilo of beef. This is the kind of thing Smil excels at: using facts and analysis to examine widely held beliefs.

Returning to the question at hand—how can we make enough meat without destroying the planet?—one solution would be to ask the biggest carnivores (Americans and others) to cut back, by as much as half. Although it might be possible to get people in richer countries to eat less or shift toward less-intensive meats like chicken, I don’t think it’s realistic to expect large numbers of people to make drastic reductions. Evolution turned us into omnivores.

But there are reasons to be optimistic. For one thing, the world’s appetite for meat may eventually level off. Consumption has plateaued and even declined a bit in many rich countries, including France, Germany, and the United States. I also believe that innovation will improve our ability to produce meat. Cheaper energy and better crop varieties will drive up agricultural productivity, especially in Africa, so we won’t have to choose as often between feeding animals and feeding people.

I’m also hopeful about the future of meat substitutes. I have invested in some companies working on this and am impressed with the results so far. Smil is skeptical that it will have a big impact—and it is true that today the best products are sold mostly in fancy grocery stores—but I think it has potential.

With a little moderation and more innovation, I do believe the world can meet its need for meat.

In his 2013 New Yorker article “Slow Ideas,” the Harvard surgeon Atul Gawande offered a compelling way to understand why some good ideas spread slowly (if at all) while others spread like wildfire.

Gawande’s story begins in 1846, when Dr. Henry Jacob Bigelow published the first account of the use of an inhaled anesthetic to produce “insensibility” during surgery. Within months, surgeons all around the world took up the idea and began using their own ether-based concoctions. When you consider that there were no phones or airplanes to carry the news, it’s amazing how fast the concept of anesthesia spread.

Gawande’s second case study begins two decades later, when the surgeon Joseph Lister reported in The Lancet that patients had much higher survival rates when he used carbolic acid to clean his hands and instruments prior to putting patients under the knife. However, Lister’s simple and effective antiseptic techniques did not go viral. It took a generation for these smart ideas to take hold.

What accounts for the difference in speed? In the case of anesthesia, the benefits of not having patients screaming and thrashing around during surgery were immediate—and they easily trumped the objections and fears that arose from clergymen and others. The same was not true of Lister’s antiseptic method. Because infection was largely an invisible problem and the symptoms appeared after patients left their surgeon’s care, the benefits of antisepsis were not as obvious. Meanwhile, there was a clear cost to doctors: the carbolic acid burned their hands.

I have found it useful to apply this thinking to the field of immunization, a field that is once again making big headlines, this time as a result of the California measles outbreak and the Ebola epidemic in West Africa. Vaccines are at once the source of both super-fast ideas and super-slow ones. Tiny injections of misinformation about vaccines often race around the globe in minutes while, in the words of Mark Twain, “the truth is still putting on its shoes.”

As with Lister’s antiseptic method, the benefits of getting the MMR or Hib vaccine are invisible while you’re sitting in the doctor’s office. For some people, invisible benefits that might materialize in the future are just not enough to get them over the clear and present fears common to all parents that something we’re exposing our children to could result in harm. As Melinda noted recently, most Americans “have forgotten what measles deaths look like.” Because of that luxury, a thin needle and glass vial can look scary.

I have new perspective on the power of those fears after reading On Immunity, by the Northwestern University lecturer and essayist Eula Biss. When I stumbled across the book on the Internet, I thought it might be a worthwhile read. I had no idea what a pleasure reading it would be. 

I also had no idea how informative it would be, even for someone like me who has been supporting and learning about vaccine research for many years. A lot of people who talk about vaccines—no matter what side they’re on—don’t invest the time to understand the topic. But Biss really did her homework. Like many of us, she concludes that vaccines are safe, effective, and almost miraculous tools for protecting our children against needless suffering.

She is not out to demonize anyone who holds opposing views. She’s a new mother who empathizes with other parents trying to make the best decisions for their children.

What makes this book so good and unusual is how effortlessly Biss moves around different topics. Her father is an oncologist and her mother a poet, which probably helps to explain how Biss so easily navigates the worlds of science and literature. And she’s just as good when she draws on insights from psychology, sociology, women’s studies, history, and philosophy.

One of the virtues of crossing so many boundaries is that it helps expand the way we view these issues. On the cover of the March National Geographic, the magazine’s editors depict vaccine refusal as an iconic example of a “war on science.” But Biss argues persuasively that distrust of science is just one factor. She explores many different things that have triggered people’s fears: pharmaceutical companies, big government, elites, toxic polluters, the medical establishment, male authority, and even vampires.

In an era when trust in just about every institution is waning, those of us who are working to increase vaccination rates face a daunting convergence of fears. What can we do to address them? First, we cannot just dismiss them as ignorant or “anti-science.” Second, I believe we have to accept that good news about vaccines is inherently slow and fears are inherently fast. The words of national experts and eloquent writers like Biss can make a difference, but when it comes to slow ideas, people are most influenced by those they know and trust—friends, family members, doctors, and teachers. As Gawande writes, “Going ‘low touch,’ without sandals on the ground,” just doesn’t work. “People talking to people is still how the world’s standards change.” 

I might read more about diseases than about any other subject. The books are not always a light read, but the more I learn, the more I’m amazed by the progress the world has made in saving lives and preventing sickness. It’s inspiring to hear about the people behind this progress: the scientists, health workers, and others who commit (and sometimes risk) their lives to help others. And understanding the mechanics of various diseases is a huge help for my work with the Gates Foundation.

Here are four good ones that I’ve read over the years.

1.

The Fever: How Malaria Has Ruled Humankind for 500,000 Years

If you want to read just one book about malaria, The Fever is probably the best choice. Author Sonia Shah doesn’t overwhelm you with data and analytics, but she does cover the whole history of the disease, which—as the title suggests—goes back further than you might think. The book was published in 2010, so it’s not totally up to date (most notably, we’ve made progress with rolling out bed nets since then). But it’s a great overview of malaria, its impact, and the solutions to it.

2.

House on Fire: The Fight to Eradicate Smallpox

Bill Foege is one of my heroes. Among his many accomplishments, he was instrumental in ridding the world of smallpox, which is still the only human disease ever eradicated. This book gives you a great view from the front lines of that battle. Bill was a mentor to Melinda and me in the early days of our philanthropy, and he continues to give us great advice today. I also recommend his deeply moving Gates Notes article about fighting river blindness. It’s a fantastic story that gives you real insight into how he thinks about his work.

3.

Smallpox: The Death of a Disease

D.A. Henderson is another hero of the global-health world who worked closely with Bill Foege on eradicating smallpox. By showing people that it really was possible to eradicate a disease, he helped lay the groundwork for the work we’re doing now to get rid of polio (which I’m optimistic will be done in 2018) and malaria.

4.

Infections and Inequalities: The Modern Plagues

Paul Farmer is one of the most impressive people I’ve had the honor of getting to know. He’s an amazing advocate for the health of the world’s poorest people, and he co-founded a system of health clinics in Haiti that reaches more than a million people in some of that country’s hardest-to-reach places. Melinda and I took our kids to Haiti this year so they could meet Paul and see the work he leads. In this book he really opens your eyes to the vast differences between the health of the rich and the health of the poor.

If you want to read just one book about malaria, The Fever is probably the best choice. Author Sonia Shah doesn’t overwhelm you with data and analytics, but she does cover the whole history of the disease, which—as the title suggests—goes back further than you might think. The book was published in 2010, so it’s not totally up to date (most notably, we’ve made progress with rolling out bed nets since then). But it’s a great overview of malaria, its impact, and the solutions to it.

Climate change is a big problem—one of the biggest we’ll face this century—but it’s not the only environmental concern on the horizon. Humans are putting down massive amounts of pavement, moving species around the planet, over-fishing and acidifying the oceans, changing the chemical composition of rivers, and more. Kolbert, a staff writer at The New Yorker, makes a compelling case that all this activity is leading to the sixth mass extinction in the Earth’s history. Think of the asteroid that wiped out the dinosaurs—only this time the cataclysm is man-made. Unlike a lot of people who write about the environment, Kolbert doesn’t resort to hype. She just lays out the facts and wraps them in memorable anecdotes. It’s a sobering but engaging and informative read.

The car I drive to work is made of around 2,600 pounds of steel, 800 pounds of plastic, and 400 pounds of light metal alloys. The trip from my house to the office is roughly four miles long, all surface streets, which means I travel over some 15,000 tons of concrete each morning.

Once I’m at the office, I usually open a can of Diet Coke. Over the course of the day I might drink three or four. All those cans also add up to something like 35 pounds of aluminum a year.

I got to thinking about all this after reading Making the Modern World: Materials and Dematerialization, by my favorite author, the historian Vaclav Smil. Not only did I learn some mind-blowing facts, but I also gained a new appreciation for all the materials that make modern life possible.

This isn’t just idle curiosity. It might seem mundane, but the issue of materials—how much we use and how much we need—is key to helping the world’s poorest people improve their lives. Think of the amazing increase in quality of life that we saw in the United States and other rich countries in the past 100 years. We want most of that miracle to take place for all of humanity over the next 50 years. As more people join the global middle class, they will need affordable clean energy. They will want to eat more meat. And they will need more materials: steel to make cars and refrigerators; concrete for roads and runways; copper wiring for telecommunications.

I had already read Smil’s books on energy and diet. Smil says at the start of Making the Modern World that he won’t spend much time on those topics (which means climate change doesn’t come up much). Instead he’s interested in the materials we use to meet the demands of modern life. Can we make enough steel for all those cars and enough concrete for all those roads? What are the risks if we do? In other words, can we bring billions of people out of poverty without destroying the environment?

Smil excels at answering big questions like these. Although he doesn’t make many predictions, he does something that’s even more valuable: He explains the past. He helps you understand how we got where we are, which tells you something about where we’re going. I study Smil’s histories so I can understand the future.

He argues that the most important man-made material is concrete, both in terms of the amount we produce each year and the total mass we’ve laid down. Concrete is the foundation (literally) for the massive expansion of urban areas of the past several decades, which has been a big factor in cutting the rate of extreme poverty in half since 1990. In 1950, the world made roughly as much steel as cement (a key ingredient in concrete); by 2010, steel production had grown by a factor of 8, but cement had gone up by a factor of 25. This animated GIF shows the dramatic transformation of Shanghai since 1987. Most of what you’re seeing in that picture is concrete, steel, and glass.

You can also see the importance of concrete in the graphic below, which illustrates what Smil calls the most staggering statistic in his book:

One material that I have a personal interest in is paper (which comes in a distant third in terms of annual production, behind cement and steel). I’ve been saying for many years that widespread computing would eliminate the need for paper, so I was curious to see where Smil thinks things stand. According to his research, paper production started dropping in the United States in the mid-90s and in Japan a few years later. But global consumption is still going up, driven by China and other growing Asian countries. In 2011 China alone accounted for just over 25 percent of the global paper supply. It was also the world’s top importer of waste paper for recycling. The odds are decent that the junk mail you tossed into the recycling bin last night is headed for China.

I still think we’ll see a paperless office someday, given the downward trend in the United States and elsewhere and the rise of ubiquitous computing. But Smil reminded me that the death of paper is a long way off. This is another reason I like to read him—he keeps my optimism from getting out of hand.

After reviewing the trends, Smil introduces a surprising and counterintuitive idea he calls relative dematerialization. As innovation lets us make a given product more efficiently, with fewer materials or energy, prices go down and consumption goes up. Someone figures out how to make cell phones with less metal, which makes them cheaper, which makes them more widespread. Less metal per phone, but more phones, so more metal overall. “Less,” he writes, “has thus been an enabling agent of more.”

Here’s how the idea applies to soda cans:

What does all this tell us about the future?

First, the good news: Thanks to technical advances, we can make major industrial products like steel and cement more efficiently than ever. On average, making a ton of steel today takes a third as much energy as it did in 1950, and produces 10 percent less carbon.

On the other hand—getting back to relative dematerialization—there’s no end in sight to the rising demand for more materials. Even though the richest countries are leveling off, many other countries are catching up. Smil points out that if the poorest 80 percent of the planet reaches a living standard that’s just a third of what people in rich countries enjoy, the world should expect to continue using more materials for generations to come.

So if consumption won’t level off anytime soon, are we doomed to run out of the stuff that makes modern life possible? As usual, Smil refuses to provide pat predictions. He does say we shouldn’t lose sleep worrying about running out in the next 50 years. Beyond that, there are a lot of variables, but we might need to limit the use of some materials or do a better job with recycling. Smil nods to several innovations that could help avoid future shortages, such as new materials that could cut our need for cement by 65 percent.

I agree with Smil that humans have an amazing capacity for finding ways around scarcity by using materials more efficiently, recycling them, or finding substitutes. The big concern isn’t so much whether we will run out of anything—it’s the impact that extracting and using these materials is having on the planet. For example, the cement industry now accounts for about 5 percent of all carbon-dioxide emissions. That’s one reason I think that developing affordable energy that produces zero carbon is one of the most important things we can do to lift people out of poverty.

I’m also surprised that the oceans get so little attention compared with other environmental problems, and I think they deserve more. They are being overfished and the waters are turning more acidic, killing off coral reefs around the world. Smil cites estimates that at least 6.4 million tons of plastic litter enter the oceans every year. We may have already done irreparable damage to these precious resources.

Above all, I love to read Smil because he resists hype. He’s an original thinker who never gives simple answers to complex questions. He gives me a lot to think about on my drive to work, before my first Diet Coke of the day.

The year 1981 was a big one in my business life. It was the year Paul Allen and I incorporated Microsoft in our home state of Washington.

As it turns out, 1981 also had big implications for my current work in health, development, and the environment. Right when Paul and I were pulling all-nighters to get ready for the release of the MS-DOS operating system for the brand new IBM-PC, two rival professors with radically divergent perspectives were sealing a bet that the Chronicle of Higher Education called “the scholarly wager of the decade.”

This bet is the subject of Yale history professor Paul Sabin’s new book. The Bet: Paul Ehrlich, Julian Simon, and Our Gamble over Earth’s Future provides surprising insights for anyone involved in addressing the world’s “wicked problems.” Most of all, it gave me new perspective on why so many big challenges get bogged down in political battles rather than being focused on problem-solving.

So what was the bet? University of Illinois economist Julian Simon challenged Stanford biologist Paul Ehrlich to put his money where his mouth was and wager up to $1,000 on whether the prices of five different metals would rise or fall over the next decade. Ehrlich and Simon saw the price of metals as a proxy for whether the world was hurtling toward apocalyptic scarcity (Ehrlich’s position) or was on the verge of creating greater abundance (Simon’s).

Ehrlich was the country’s, and perhaps the world’s, most prominent environmental Cassandra. He argued in books, articles, lectures, and popular television programs that a worldwide population explosion threatened humanity with “the most colossal catastrophe in history” and would result in hundreds of millions of deaths from starvation and dire shortages not just of food but all types of raw materials.

Simon, who passed away in 1998, was a population optimist. A disciple of conservative University of Chicago economist Milton Friedman, Simon believed the doomsayers’ models gave little or no credit to the power of efficient markets and innovative minds for developing substitutes for scarce resources and managing out of crises. He went so far as to claim that population growth should “thrill rather than frighten us.”

At the time of the bet, Simon was a relatively unknown scholar who loved using the eminent Ehrlich as a foil. In public, Ehrlich didn’t even acknowledge Simon by name. Nonetheless, Ehrlich rose to Simon’s bait. “It seemed a small price to pay to silence Julian Simon for ten years,” in the words of Sabin.

Who won the bet? Simon. Definitively. Even as the world population grew from 4.5 to 5.3 billion in the 1980s, the five minerals that were included in the bet—chromium, copper, nickel, tin, and tungsten—collectively dropped in price by almost half. Ehrlich begrudgingly made good on the bet. But to this day he still does not concede that his predictions of Mathusian horrors have been off the mark. Similarly, he does not acknowledge that the discipline of economics has anything of value to contribute to discussions of population or the environment.

Even though I had gone back in recent years to read Ehrlich’s Population Bomb (1968) and the Club of Rome’s intellectually aligned book Limits to Growth (1972), The BetLimits to Growth was a stark reminder to me of how apocalyptic a big part of the environmental movement has been. Ehrlich claimed to have science on his side in all of his predictions, including how many people the Earth can feed. He stated as scientific fact that U.S. lifestyles were unsustainable, calling developed countries “overdeveloped countries.” claimed the credibility of computer modeling to justify its predictions of apocalypse.

Simon was equally extreme in his rhetoric. He was as reflexively dismissive of the discipline of ecology as Ehrlich was of economics. And his sound bites provided great fodder for Ronald Reagan and other conservative politicians eager to push back on the pronouncements of environmental scientists. But history generally has been kinder to his predictions than those of Ehrlich.

We know now that Ehrlich was extremely wrong and that following his scientific certainties would have been terrible for the poor. He floated the concept of mandatory sterilizations. He pushed aggressively for draconian immigration policies that, if enacted, would have kept out much of the foreign talent that came into the U.S. over the past three decades and added greatly to the U.S. economy. Ehrlich and his fellow scientists criticized the Green Revolution’s agricultural innovations because, in his view, “we [will] have an even bigger population when the crash comes.”

On population, Ehrlich ignored the evidence that countries that developed economically dropped their birth rate. (The current view is that population will rise only modestly after hitting a bit over 9 billion by 2050.) Granted, population growth is a huge issue in some poor countries, where it creates locally some of the instability and scarcity that Ehrlich foresaw for the entire world. But fortunately, there is strong evidence that if we continue to produce innovative reproductive health tools and make them available to women who want them, and we keep pushing forward on economic growth, there will be fewer and fewer of these places in the decades ahead.

Matt Ridley’s book The Rational Optimist (2010) is probably the best statement today of the Simon case, and Ridley was more careful than Simon was in his claims. Even though I agree with a lot of the book, it too easily dismisses the need to address problems of the poorest, climate change, and the oceans.

The recent Economist special report on biodiversity makes a strong case that economic growth allows us to make environmental concerns a priority. It contrasts the environmental record of the rich countries with that of poor countries to say that economic growth is the best hope for environment protection. All of this suggests to me that we should be wary of broad attacks on economic growth. (The authors of the special report admit that it’s not focused on climate change and mostly leaves aside the mismanagement of the oceans, which is tragic problem that deserves more focus.)

I recommend The Bet to anyone wanting to understand the history of the divisive discussions we have today, especially the stalemate over climate change. Sabin makes a strong case that Ehrlich’s brand of science made it easy for conservative critics to caricature environmentalists as doom merchants and fear mongers who peddle dubious science as a means of advancing their big-government agenda.

And Simon is far from blameless. “Julian Simon and other critics of environmentalism … have taken far too much comfort from extravagant and flawed predictions of scarcity and doom,” writes Sabin. “By focusing solely and relentlessly on positive trends, Julian Simon made it more difficult to solve environmental problems.”

It’s a shame that extreme views get more attention and more of a following than nuanced views. We see this dynamic clearly when the Intergovernmental Panel on Climate Change does its best to be clear and impartial in conveying what is known on the key issues, but both liberals and conservatives make it hard for the public to understand the panel’s nuanced conclusions.

I wish there more people who took the middle ground and who were as prominent as Simon or Ehrlich. So here’s my question to you: What’s the best way to encourage scholars to combine the best insights from multiple disciplines? How can we elevate the status of scientists and spokespeople who refuse the lure of extremism and absolutism? 

By “this,” I don’t just mean the rainforest you see in this photo. I mean everything that can be consumed on Earth: plants, animals, all of it. And by “we” of course I mean people.

It’s such a big question that many people wouldn't even know where to start.

But if you care about understanding the impact that humans are having on the Earth, and what that means for our future, it’s a crucial question. Vaclav Smil sets out to answer it in his book Harvesting the Biosphere: What We Have Taken From Nature.

There is no author whose books I look forward to more than Vaclav Smil. He jokes that no one reads his books (he’s written more than 30 of them). It’s true that each book only sells a few thousand copies. But I’m trying to read everything he writes.

Why? He understands a phenomenal range of subjects, from energy to agriculture. On any page he might talk about meat-eating among bonobos or the average human life span during the Roman Empire. Plus he is rigorously numeric, using data to illuminate every topic he writes about. The word “polymath” was invented to describe people like him.

In Harvesting the Biosphere, Smil gives as clear and as numeric a picture as is possible of how humans have altered the biosphere. The book is a bit dry and I had to look up a number of terms that were unfamiliar to me, but it tells a critical story.

Smil starts with a big question: How much life is there in the biosphere? By “biosphere,”he means everywhere on earth where there are living things: in the air, on the ground, and in the oceans. I’ve been thinking and writing a lot about measurement this year, and I was very impressed with how rigorously he thinks about this problem. Ultimately he concludes that the dry mass of all living things on Earth is about 1.6 trillion metric tons. (Because living things contain different amounts of water, Smil makes these calculations using dry mass, which leaves out the water.)

Smil tries to figure out what portion of the biosphere's primary productivity—the amount of plant life generated each year by photosynthesis—is consumed by humans. He estimates that we will harvest roughly 17 percent of what the biosphere grows this year—mostly plants. (He admits it could be as little as 15 percent or as much as 25 percent.)

He describes vividly how humans’ impact on the Earth has changed over time. We first had a big impact roughly 10,000 years ago, when we figured out how to burn down forests to clear land for crops. Today we harvest crops for four main purposes: to feed animals, feed humans, generate fuel, and make paper and construction materials. Smil shows how out of all these, the first two are responsible for the biggest impact on the biosphere. About 12 percent of the Earth’s land mass is now devoted to farmland.

Twelve percent is a big number, but it would be even bigger if it weren’t for innovations in crop breeding, field machinery, and other areas that made farming much more efficient. If crop yields had remained stagnant since 1900, in the year 2000 we would have needed nearly four times more crop land to feed everyone. That’s practically half of all the ice-free land in the world.

We’ve also had a huge impact on the biosphere by building major cities, which essentially eliminate or drastically reduce any natural productivity from those areas. Smil notes that major cities now cover nearly five million square kilometers. If you clustered them all together, they would cover an area 50 percent larger than India.

Here’s another way to see our impact on the biosphere. Which do you think weighs more—human beings and domesticated animals, or all the wild vertebrates in the world? I would have guessed all the vertebrates. Here are the facts: In 2000, the dry mass of humans was about 125 million metric tons. For all domesticated animals, it was 300 million tons. That’s a total of 425 million tons, compared to just 10 million tons for all wild vertebrates. It’s pretty mind-blowing.

In the course of reading the book you learn a great deal about how population and consumption have changed over time. It is amazing how little meat was available in most diets as recently as 1800: just a few kilograms per year, versus about 100 kg of meat per year in an average American diet today. (The average Indian, by contrast, eats about 10 kg of meat each year.) The world now harvests far more crops to feed animals that produce meat, dairy, and eggs than to feed humans.

But in some ways we've been less responsible in the sea than on land. We don’t harvest a high percentage of all the life in the sea, but we concentrate on a very few species—especially carnivorous fish, like cod and tuna. Smil writes that most of the traditionally targeted species and major fishing areas are now being fished to capacity if they’re not already overfished, near collapse, or collapsing. It’s a sobering picture.

What does all this mean for the decades ahead?

Smil looks at the future with some concern. As more people join the middle class, they will demand more to eat, and more meat in particular, which will put an even bigger strain on the biosphere. He lists a number of steps we could take, which boil down to various ways to manage resources more carefully, stabilize the global population, and pursue research that will raise crop yields.

I was a bit surprised that he didn’t talk more about innovations that will help avoid some of the problems he’s concerned about. For example, he writes a lot about the impact of meat-eating on the biosphere. Producing meat is very inefficient: To get 1 kg of edible meat from a cow, you have to feed it about 10 kg of grain. But he doesn’t mention the possibility of making alternatives to meat, which could reduce the inefficiency and the need for additional crops. (A few months ago I posted a neat feature about research on alternatives to meat. I’ve tasted a few and they’re very convincing.)

I had a chance to ask Smil about this when we met this year. He pointed out that humans eat about 300 million tons of meat a year, and producing even a small percentage of that amount in meat alternatives would be a real challenge. I agree that it’ll take more research, but I remain optimistic that it could help reduce the impact of meat-eating on the earth.

Anyway these criticisms are relatively minor. If you want to learn about agriculture or the environment and you have the patience to stick with it, this is a great text.

In Harvesting the Biosphere, Vaclav Smil carefully adds up how much life exists on Earth. Without moralizing, he makes a convincing case that humans could soon consume an unsustainable share of life on Earth.

I recently read an important new book that explains why nearly 1 billion people in the world are still suffering from chronic hunger, and how that number will increase in the next several decades unless we act to increase the global food supply.

The book, One Billion Hungry, is by Gordon Conway, one of the preeminent experts in sustainable agricultural development. For people who want to learn about the connection between agriculture and world hunger, this book may be the best broad overview of how our modern food production system is tied to agricultural practices. It’s also very readable.

The picture Conway paints is a sobering one. Biofuel crops are competing with food crops for a decreasing supply of cultivatable land. Rising incomes in developing countries are driving up demand for resource-intensive meat products (a cow consumes eight pounds of grain for every pound of meat produced). These and other factors are pushing food prices higher and creating price spikes that are especially hard on poor families already spending most of their income on food.

Additionally, pollution, salinization, and inefficient use of existing water supplies are causing rivers to dry up and groundwater levels to decline. The rate of growth in yields of two key food staples—rice and wheat—is declining. By 2050, the world population is expected to increase from 7 billion to 9.1 billion—mostly in developing countries. And the consequences of climate change—higher temperatures and more frequent droughts and floods—are starting to impact agricultural productivity.

Taken as a whole, it can seem like a pretty frightening scenario. Like Conway, though, I’m optimistic that we can solve these problems if we start now. Ironically, one of the challenges we face is overcoming the complacency that set in after the success of the Green Revolution a half-century ago.

The Green Revolution was a series of agricultural research projects leading to the development of new corn, wheat, and rice seeds—and more productive farming practices—introduced throughout Latin America and Asia. Yields skyrocketed, resulting in lower food prices, less hunger, and lower poverty. The mass starvation predicted by one prominent academic researcher, Paul Ehrlich, in the 1968 book The Population Bomb, never came to pass.

One of the interesting points Conway makes in his book is that the success of the initial Green Revolution was as much about creating “the enabling environment” as it was about scientific advances. “Governments made substantial investments in agricultural research, in ensuring farmers had access to credits and input, and in getting markets to work efficiently. The favored countries benefited from governments willing and able to make and direct the necessary investments.”

Conway argues that we once again need to make agriculture more efficient and productive, less susceptible to variations in weather and markets, more equitable, and environmentally sustainable. He argues, and I agree, that this requires renewed political leadership, greater public and private investments in sustainable agricultural research and extension, better access to markets for smallholder farmers, and farmer-centered government policies and strategies that ensure women and children are getting adequate nutrition.

In particular, we need to pay close attention to Sub-Saharan Africa, which for a variety of reasons was bypassed by the first Green Revolution. Today, more than one of every four people in Sub-Saharan Africa is chronically undernourished—a significantly higher percentage than anywhere else. (Hundreds of millions of people are also still going hungry in Southern and Eastern Asia)  

The good news is that the global development community is smarter today about making sure that breakthroughs in seeds and technologies developed in rich and middle-income countries are making their way to farmers in poor countries. More information about best practices is getting to them. The tools of digital technology are working in their favor. And we’re seeing progress in connecting smallholder farmers to regional and global markets so they can grow and sell a wider variety of crops, in addition to whatever they’re already growing for their own consumption.

In some ways, I’m more optimistic than Conway that science-driven advances can strengthen our food security. The science of agriculture is actually at a pretty exciting stage. The tools of the biological revolution that were invented to understand human health apply very directly to understanding plants as well and could make a profoundly positive difference in the years ahead.

I agree with Conway that the wildcard in boosting agricultural productivity on a sustainable basis is climate change. Although climate change is being driven mainly by the activities of industrialized countries, the negative impact will be greatest in developing countries. It is likely to result in shorter growing seasons, higher temperatures, and extreme weather events such as flooding and periods of drought. Many areas in the developing world are already experiencing water shortages. Many crops can’t tolerate even a minor increase in temperature.

Conway also points out that agriculture contributes to climate change through the clearing of forests and emissions of nitrous oxide and methane. He believes agriculture can become part of the solution through development of new technologies and systems that reward farmers for mitigating emissions.

Beyond that, society as a whole must address the underlying causes of climate change to ensure a stable food supply for the world.

Conway’s book is well organized, with chapters on hunger, agricultural innovation, and environmental challenges that can easily be read on their own. Feeding our growing world is fundamentally important to all of us, no matter where you live. If there’s one book I’d recommend reading to get the definitive story about the state of agriculture today and what we need to focus on to increase productivity and eliminate hunger, it would be One Billion Hungry.

Sometimes people have suggested that I’ve got a “photographic memory,” particularly when I’m talking about topics that interest me, like science and business. It’s a nice compliment, but it’s not really true. Not even close. For example, my friend Mike is so much better than I am at remembering movie facts—what actor was in which movie and when it was made. I can’t do that.

I do still remember every line of the first complex software program I ever wrote. Because I spend a lot of time thinking about science and business, I have a structure or a context that the facts can fit into. Like, “Oh, this company is like that one, but different in this way.” I think most people have good memory for things in the domains they’re really interested in.

I never thought much about whether I could improve my memory across a wider set of domains, but now I think I could, after reading Moonwalking with Einstein: The Art and Science of Remembering Everything, by a young science writer, Joshua Foer. It’s absolutely phenomenal, one of the most interesting books I’ve read this summer.

Foer got interested in memory as a way to understand how the mind works. That took him to the world memory contest, where people can do things like memorize the order of a deck of 52 cards in just a few minutes. He was fascinated. He wondered: Are some people born with very good memories? But it turns out, except for people like the main character in Rain Man—and just a very few other people whose brains are wired differently—the average human memory is extremely good at tasks that are important to you, and extremely poor at things that aren’t as important.

That’s why just trying to force a bunch of random facts into your head is hard. But you’re extremely good at remembering faces or images, visual memory being a survival advantage in our evolutionary history. It’s amazing. You can flash thousands of images at people, and they can recall seeing them and can notice small changes in them even days later.

Lots of practice in visualizing is key to a strong memory. When you’re reading a book, you don’t sit there and say, “Well, what does that word mean? What does that word mean?” After many sightings of the words in your vocabulary, your recall is immediate and very, very good. Domain expertise works the same way. If you play bridge for 20 years, you have seen many bridge hands and you recognize patterns in them, which can give you a phenomenal ability to remember a new bridge hand. (I’ll admit to being a long way off from this kind of bridge recall.)

Foer discovered that the people who win memory contests use certain techniques for visualizing things, techniques mostly developed in ancient Greece. They talk about what they do as building a memory palace – often, literally visualizing a house with many rooms and different people and things in each room, representing what they are trying to remember. “Garlic on the driveway.” “Cottage cheese at the doorstep.” Things like that. The idea comes from an ancient Greek poet who remembered the names of everyone who was killed when a temple collapsed during a banquet. He had a visual memory of where everyone was seated.

Foer wasn’t sure these techniques really worked, so he spent a year practicing them every day. After just a year, he entered and won the U.S. Memory Championship. He actually broke the U.S. speed record for memorizing a deck of cards. He did it by learning to associate each card with a person, action or place. Then, remembering an image like moonwalking with Einstein helped him to recall three cards in the right order, and he only needed to remember 17 such images to memorize the whole deck.

When I first heard of someone memorizing a deck of cards, I thought, “I couldn’t do that.” Now I think, “Hey, I could do it,” although I haven’t started to try yet.

Like most people, I’m fascinated by how the mind works, and memory is a big element of that. Part of the beauty of this book is that it makes clear how memory and understanding are not two different things. Building up the ability to reason and the ability to retain information go hand in hand.

Don’t believe anybody who tells you it’s easy, though. Most of us will have to practice for months and months and months. You have to be very serious about it. The book reminds us that we all start off with pretty much the same tools for the most part, and we can be intentional about strengthening them, or not.

I gave a TED talk in 2011 on state budgets, which is where the majority of the money for education comes from. As you look at the growing burden on states from government workers’ benefits, retiree and Medicaid costs, it’s clear that the present rate of growth will soon become unsustainable. 

Today, medical spending in the U.S. is 17% of GDP, or over $2.5 trillion—more than any other country in the world. Medical inflation has been running 2 percentage points higher than the economy. Continuing on this path will lead us to an insupportable level of spending on healthcare as a percentage of GDP, and could have a devastating impact on government spending for other programs, like education. The rapid rise in health care costs is obvious, but unfortunately with so many complicated factors involved, the solution is not.

Amanda Bennett’s memoir, The Cost of Hope tells a very human story about her husband Terence and his battle against a rare form of kidney cancer. Amanda’s story is personal, filled with moments of anguish, grief and love but she also tries to draw attention to what she discovers is a flawed health care system. It is a perfect example about why all of the hard decisions about health care spending are just that.

What makes this memoir interesting is that there are not many books where the author speaks first-hand about the administration of our health care system or gives real life explanations to the current cost crisis.

An executive editor at Bloomberg News and a Pulitzer Prize-winning journalist, Bennett is an ultra-thorough researcher and applied her trade as an investigative reporter to try to decipher the complexity of her husband’s medical bills in the years after he died. She wanted to understand the maze of medical bills and, she writes, “what they would show about end-of-life care—its science, emotions, and costs.”

For Amanda and Terence there were only a few moments of financial stress because she had very good health insurance provided by her employers during his seven-year illness. In Amanda’s words, “as we made our way through a series of expensive last chances…we didn't have to think about money, allocation of medical resources, the struggles of roughly 46 million uninsured Americans, or the impact on corporate bottom lines.”

Their contribution to medical expenses was minimal and since there was no impetus to account for the cost of each procedure or drug, it wasn’t until Amanda puzzled over the 5000 pages of documents from insurers, hospitals and doctors that she realized just how expensive treatment had been. Medical care totaled $618,616 but, she writes, “For me, it was about pushing the bell curve. Knowing there was something to be done, we couldn't not do it.  It is hard to put a price on that kind of hope.”

However she also writes, “since more than a quarter of all medical care is provided in the last two years of life, surely we must come up with a better way of helping ease families to gentler—and less costly—transitions.”

She raises more fundamental questions in her book about the disparity of costs for the same procedure, not only when they moved from hospital to hospital but when she changed insurance carriers. She also talks about whether at the time, had they been able to clarify some of the costs, would they have made wiser or less expensive choices? This lack of information transparency in U.S. health care strikes me as a fundamental problem as we try to fix a system that most people would admit is broken.

Complication, cost, competition (and the lack thereof) and equality of care - they are all poignantly played out in this book. It is a graphic reminder of the complexity of the problem through the lens of someone who has tragically lost a loved one.

Emotions run high in the debate about our health care system. I’m trying to get smarter about the pressures that maintain the status quo and ways we could try to address the multiple problems of cost and access. I am convinced that if we do not take a hard look at our system, it either will implode or will rob us of our ability to fund other important priorities. 

I had a chance to talk with Yergin when we were both at the ECO:nomics conference hosted by the Wall Street Journal. He’s an impressive guy and a true expert in energy. He’s also an extremely articulate writer, as evidenced by his Pulitzer prize for his early work on oil, The Prize.

Yergin is best known as an expert on the oil and gas industries, but The Quest is quite comprehensive in looking at many different kinds of energy. It covers a lot of ground and is filled with a ton of facts and data. But it’s a fast read because Yergin relays information through stories that are very well told.

I found Yergin’s account of the history of oil exploration to be useful because it helps bring perspective to discussions of whether we’re in danger of running out of oil, whether production is likely to peak soon. Throughout history and still today, we keep finding more oil than we use. Reserves today are higher than at any time in history, not only for oil but also for natural gas and coal. This may be good news for traditional energy, but it shouldn’t lull us into complacency about aggressively pursuing low-carbon and no-carbon energy technology.

Yergin critiques the overly simplistic idea that we’re running out of oil, but he also questions the techno-optimists because of the costs and complexities involved in building new energy systems. He gives you the data to understand better what’s likely to happen in the future, but doesn’t try to pretend that he knows how everything will turn out. He doesn’t try to predict when or if solar energy will be cheap enough to compete with traditional energy sources, or whether we’ll get breakthrough batteries. 

There are many complex issues in the energy sector. I’m most concerned with the impact of different energy sources and what they could mean for the world’s poorest and for carbon emissions overall. That’s why I wish Yergin had included an overview of the energy-for-transportation market, which is basically oil, versus the energy-for-electricity market, which is a mix of gas, coal, nuclear and renewables. The two markets are basically separate today, but will they stay that way? Will electric cars really take over? Will we be able to convert natural gas and coal into liquids? 

His book is a real contribution to a debate that deserves far more attention, in my view. At 816 pages, it’s a commitment, but one that you’ll find worthwhile thanks to Yergin’s expertise as an energy expert and writer.

Some of my favorite online videos are physics lectures by Walter Lewin of MIT. Lewin is an incredible teacher who’s passionate about the beauty of physics and its power as a way of looking at the world. He really brings science to life. One of his famous classroom demonstrations, which is on video, involves a pendulum that you think is going to hit him and hurt him, but because it’s slowly losing momentum it never quite touches him, although it comes so close that it’s a bit scary.

Part of what makes Lewin a great teacher is that he has a lot of energy and enthusiasm, and fun ways of explaining things. If he ever explains something the wrong way on his videos and a viewer catches it, even a small mistake, Lewin inserts a little video pointing out his error—he has a nice way of saying “oops” about things. 

He began teaching when he was very young at a school his parents ran in the Netherlands, a school that taught business skills. When he got to MIT, he put a lot of his energy and enthusiasm into an introductory physics course. It’s famous for his demonstrations, which raise questions, which lead to more demonstrations, which lead to answers and equations—instead of starting with the equations. 

Lewin’s teaching skills come through in his wonderful book, For the Love of Physics, which is good even if you don't know much physics. He'll introduce a mystery and then show how you can understand it with just a little bit of physics. He helps you appreciate that physics is pretty basic stuff. Like, what is metal?  What is it good at?  Why can we build big buildings today and cars and planes, but hundreds of years ago they couldn't do that stuff?  Why are there stars and what's going on in a star?  And why can phones work?  Wireless phones?  And what is a microchip, what's going on there? 

Fortunately, if you understand just a few physics concepts, like electromagnetism and gravity, you can understand a lot, like how a global positioning system works, or how a DVD can store a movie. That’s why everybody should know some physics. Not necessarily relativity, maybe, or about all the weird sub-particles beyond protons, neutrons and electrons. But it would be great if people knew what Newton knew and other physicists knew up to around the year 1890. Then you can understand why things orbit and fall, and what’s going on when two cars crash. A little bit of physics goes a long way in helping you understand a huge number of things. 

Lewin believes that all science, even theoretical physics, is ultimately experimental. That’s why he’s skeptical of ideas like string theory, which do not yield experimental predictions. I wish more people shared Lewin’s appreciation for observation, measurement and data—especially in debates over incredibly important matters that concern me very much, like public finance, climate change, education reform and vaccinations. In our foundation’s work, we try hard to make sure that our efforts are based on good data and subject to rigorous evaluations based on the evidence. The data sometimes surprises or disappoints us, but we need to confront it if we’re going to have any chance of being successful in the long run.

Lewin is an inspiring example of a scientist who is dedicated to careful observation, measurement and experimentation, the most reliable routes to real knowledge. He is unique, but we all can learn a lot—about teaching and life, as well as physics—from him, his lectures and For the Love of Physics.

Through my work at the foundation, I’ve been fortunate to meet some amazing people who have had a huge impact on the world. But, one person I’ll always wish I could have met is Norman Borlaug, a remarkable scientist and humanitarian whose work in agriculture has influenced my thinking and the foundation’s work with small farmers in the world’s poorest countries.

Fortunately, there is a great biography of Borlaug, The Man Who Fed the World, which I highly recommend. Although a lot of people have never heard of Borlaug, he probably saved more lives than anyone else in history. From the mid-1940s through the mid-1960s, Borlaug and a team of scientists successfully developed and introduced high-yielding, disease-resistant wheat seeds and new growing methods in Mexico, dramatically increasing the country’s agricultural production.

Just as Mexico was reaping the agricultural, social, and economic rewards of Borlaug’s efforts, tens of millions of people were on the verge of starvation in South Asia. One scientist, Paul R. Ehrlich, provocatively predicted in a controversial 1968 book, The Population Bomb, that hundreds of millions of people would die of starvation over the next few decades – no matter what anyone did.

Undeterred, Borlaug led the effort to ship thousands of tons of the wheat seeds developed in Mexico to farmers in India and Pakistan. In just a few years, wheat yields in both countries nearly doubled. India and Pakistan became self-sufficient in wheat production. And Borlaug, who became known as the father of the Green Revolution, was awarded the Nobel Peace Prize.

It’s interesting to me how much criticism there has been of Borlaug over the years. It’s almost like people forget, or perhaps never really understood, what he did for humanity. It’s estimated that his new seed varieties saved a billion people from starvation.

But the significance of his work goes even further. When people get enough food to eat, their health improves and they are less susceptible to disease. In children, especially, improving their nutrition dramatically improves their brain and physical development. Much of the dramatic increase in productivity coming out of Asia over the last few decades is due to Borlaug’s Green Revolution.

One of the criticisms of Borlaug’s methods is the overuse of fertilizer. Even as great as his seeds were, they don’t grow magically. It’s true that there is a negative effect from the overuse of nitrogen, one of the key ingredients in fertilizer. It can flow into rivers and create algae blooms that kill fish. Today, as we look at increasing agricultural productivity, we do need to be smarter about how fertilizer is used in order to avoid these problems. For example, it can be applied in smaller doses near the root and irrigating can be done in a way that minimizes the flow of nitrogen into rivers.

The other main criticism was that the Green Revolution mainly benefited large farmers. In the first decade, it was those farmers who could afford fertilizer and understood seeds that did better. But in the second decade, there was an equally beneficial effect for small farmers. We do a lot of work through the foundation to help small farmers in poor countries, so we’re always watching out for inequities that hurt them.

Over time, the Green Revolution expanded to include other key crops such as rice and maize (corn). But for a variety of reasons, the agricultural innovation needed to create a breadbasket for Africa never got off the ground.

Seven or eight years ago, I came across a book, The Doubly Green Revolution, that really opened my eyes to the need for a Second Green Revolution to feed the hundreds of millions of people in Africa who are on the edge of starvation. The author, Sir Gordon Conway, a British agricultural ecologist, talks about the need for scientists and farmers in poor countries to work together to develop better plants and more sustainable agricultural practices. Conway also talked about the importance of creating better economic opportunities for poor farmers, who often are women.

Another book that influenced my thinking is The State of Humanity, a collection of essays edited by Julian Simon, an environmental economist. Simon believes in not underestimating the importance of technological innovation and human ingenuity in solving big problems that might seem insurmountable. This is a constant theme that I’ve always been interested in. When do people overestimate the power of innovation? When do they underestimate it? What do we need to do to foster it?

But most importantly, I have learned what’s possible in agriculture from studying Borlaug and what’s happened in the decades since his breakthroughs. We know that we need to encourage a sustainable model of agriculture. And we understand that small farmers in Africa and South Asia must be involved in developing and testing the agricultural advances needed to feed the hundreds of millions of people who are still going to bed hungry most nights.

Norman Borlaug was one-of-a-kind—equally skilled in the laboratory, mentoring young scientists, and cajoling reluctant bureaucrats and government officials. The second Green Revolution may not produce another Norman Borlaug, but his achievements and influence will continue to guide our work at the foundation and in agricultural development around the world.

Very few science books are worth reading 40 years after they were written. Only a few classics—like Richard Feynman’s books on physics or perhaps some of Richard Dawkins’ books—are so well-written and clear that they still make for good reading. James Edward Gordon’s book, The New Science of Strong Materials: Or Why You Don't Fall Through the Floor, belongs in this unique category. Despite the word “new” in the title, was written back in 1968.

I have always wondered why some materials are strong and some are weak, why some crack under pressure and others flow, and what materials can be used for building bridges and tall buildings. There are so many amazing things about the properties of different materials. Why is it when you look around for tall things they are mostly made of iron or wood? What is special about metals? Why is iron with various impurities such a unique material? How does nature build strong things like wood? Why is a diamond hard but not strong? What is the magic of composite materials?

A few years ago, I toured the Hagia Sophia, a 1,500-year-old cathedral (now a museum) in Istanbul considered to be one of the greatest building projects of all time. Looking up at the enormous central dome and smaller half domes, I marveled at the genius of the ancient engineers and architects who figured out how to span pumice bricks across an area 200 feet by 100 feet, and 240 feet high, with no supporting pillars or beams. Sophia’s builders understood enough about the science of materials and the physics of large structures to know that they needed to maintain a state of compression in critical regions of the building. But not everyone back then did, as Gordon wryly notes: “It is not surprising that the roofs of churches continued to fall upon the heads of their congregations with fair regularity throughout the ages of faith.”

I always thought that at some point in the evolution of chemistry, after we understood crystalline structure, we would begin to learn why some things are strong. Unfortunately, that never really happened. I went and bought some graduate texts on materials but they assumed I already knew a lot about concepts like dislocations and different type of materials. What I wanted was a recapitulation of the history of materials told in an interesting and approachable way. That is what The New Science of Strong Materials provides.

There are a lot of words used to describe materials, such as strong, brittle, tough, or ductile. What do these terms really mean and where do these properties come from?

Gordon starts by explaining how chemical bonds matter. It you push down on a material, the bonds vary in terms of how much they give elastically, which accounts for the stiffness of the material. Lots of materials, like rock, can take a huge amount of compressive force before breaking.

There is a big difference in how a material behaves when you push down on it (compression) versus applying force to pull it apart (tension). Rock, brick, or normal cement can take a lot of weight in compression but then will break apart very easily under tension due to cracking. Under compression, most materials deform by about 1% before they break. Under tension, only metals and composite materials can reach that level.

Amazingly, the science of cracks was not well understood until the 1960s. Gordon and his colleagues were key players in making the breakthrough in understanding. This was important because lots of ships used to break in two and bridges used to fall down because engineers weren’t able to compute stress levels. They didn’t understand that holes in a sheet of material—even small ones like a hatch on a ship or a bolt hole in an airplane superstructure—allow stress to build up in a dramatic way.

Cracks in glass come mostly from imperfections on the surface. If you can make the surface super smooth, it is very strong and can be stressed over 2% without cracking. Cracks in solid materials are different because they result from the way stress builds up in one location in the crystalline structure.

Gordon has a love of natural materials such as bones, teeth, insect cretin, and wood. He thinks we have a lot to learn from nature and he correctly predicted that there would be breakthroughs in composite materials based on the way nature defeats cracking by having “weak interfaces.” Fiberglass, which was already being used in the 1960s, was an early step in composite materials. Gordon explains how the combination of glue (resins) and fibers together makes for a strong and crack resistant material. Glues have always confused me. Even after Gordon’s explanation I need to study them a bit more.

The book closes with an explanation of metals, particularly iron in its various forms—steel, pig iron, wrought iron, and all the various alloys of steel that can be made to withstand heat or corrosion. The key to why metals don’t crack is that the various layers of the crystal structure slide over each other, a characteristic called ductility.

Iron and many other metals in their pure form are too ductile. To make a strong material, you have to avoid ductility (flowing under pressure) and brittleness (cracking). Iron with impurities (particularly carbon at about 3% by weight, but 15% by the proportion of atoms) strikes this balance very well. Iron ore has some carbon in it so the history of smelting is figuring out how to achieve the high temperatures needed to get the carbon level just right. Iron is a key material for civilization and its price came down by a factor of over 10 during the 1800s as it fueled the industrial revolution.

I admit this book is not for everyone, but if you’re fascinated about how our world is held together, it is a very cool book that I recommend. If you’re interested in the science of engineering and the physics involved in building the world’s greatest structures, I recently wrote about a fascinating course offered by the Teaching Company, called Understanding the World’s Greatest Structures. For the curious, both are certainly worth the time.

Bill Foege is one of my heroes. Among his many accomplishments, he was instrumental in ridding the world of smallpox, which is still the only human disease ever eradicated. His book gives you a great view from the front lines of that battle. Bill was a mentor to Melinda and me in the early days of our philanthropy, and he continues to give us great advice today. I also recommend his deeply moving Gates Notes article about fighting river blindness. It’s a fantastic story that gives you real insight into how he thinks about his work.

Talk to anyone old enough to remember polio epidemics in the U.S., and you will see the fear in their eyes as they talk about those terrible and unsettling times. For decades, no one knew why thousands of children would suddenly be stricken—usually in midsummer—with many dying or left permanently paralyzed.

Today, most of us in the U.S. don’t even think about polio. But if you go to villages in India’s Bihar Province or the northern states of Nigeria, or the southern part of Afghanistan, you will see that very same fear in the eyes of parents who worry that their child might be next.

I’m a dogged advocate for polio eradication and have written about it in many other articles on the Gates Notes. We are very close to ridding the world of this terrible disease once and for all. It will take focus and commitment to get it done, but I am confident we can.

That’s why I’m a fan of David Oshinsky’s insightful book, Polio: An American Story. (I’m not alone here, as it received the Pulitzer Prize for history in 2006.) It is a fascinating account of the search for a vaccine to stop the polio epidemics that swept the U.S. in the first half of the 20th century, and the remarkable efforts that led to its successful eradication from the U.S. and most other countries. Reading Oshinsky’s book a few years ago broadened my appreciation of the challenges associated with global health issues and influenced the decision that Melinda and I made to make polio eradication the top priority of the foundation, as well as my own personal priority.

Oshinsky retraces the steps of researchers trying to puzzle together how to create an effective vaccine. He’s a gifted storyteller who makes complex scientific subjects easy to understand and also captures the mood of a country terrorized by an invisible and little-understood disease. He describes in meticulous but never-boring detail the people and politics associated with one of the most important medical breakthroughs in history.

I found it interesting that the first recorded polio epidemic in the U.S. didn’t occur until 1894, in rural Vermont. By 1908, Karl Landsteiner, a Viennese researcher who later won a Nobel Prize for his discovery of the different human blood types, isolated the poliovirus by injecting monkeys with an emulsion from the spinal cord of a boy who had just died of polio. It was one of several important breakthroughs in the early 20th century battle against killer infectious diseases, including malaria, tuberculosis, diphtheria, typhoid, and syphilis.

In 1916, a polio outbreak in New York City quickly spread to adjacent states. Despite intensive sanitation measures of the kind that had helped control other epidemic diseases such as cholera and typhoid fever, 27,000 people died that summer. In New York City, 80 percent of those who died were under five.

I knew that Franklin Delano Roosevelt contracted polio, but did not realize until reading Oshinsky’s book how significant an influence FDR had on the search for a vaccine. He was struck in the fall of 1921 while on a family vacation in Canada. The news stunned Americans, who at the time believed the disease mainly occurred among poor children in slums. FDR was 39 and from a wealthy New York family.

For thousands of polio victims, Roosevelt symbolized that life could go on for those disabled by the disease. He helped found the National Foundation for Infantile Paralysis, now known as the March of Dimes, which provided aid to victims and funded polio research. I was impressed that even as president, FDR would often respond personally to letters sent to him by other victims. Yet, Roosevelt also went to great lengths—abetted by a cooperative press corps—to hide the fact that he needed leg braces and handrails to stand, and a wheel chair to get around. I can’t imagine an American president being able to do that today, but FDR was greatly admired at a time when the nation was dealing with a world war and the Great Depression. Somehow, he persuaded the media that obscuring the extent of his disability was necessary to reassure the public that he was healthy and capable of holding public office.

I was also fascinated by the media savvy and marketing sophistication of the March of Dimes, which used famous Hollywood actors to get out its message and was the first philanthropic organization to introduce the idea that millions of Americans—not just the wealthy—could play an important role in helping solve big social problems. In 1938, Americans mailed nearly 2.7 million dimes directly to the White House in support of that year’s March of Dimes campaign.

We sometimes take for granted the speed of scientific breakthroughs today. Yet, Oshinky’s book reminded me of the painstaking efforts scientists often must undertake. Forty years after the polio virus was discovered, scientists still didn’t know what caused it. Theories ranged from rotten fruit to houseflies to contaminated milk. They didn’t know the mechanism by which it attacked the central nervous system. They didn’t know if there was just one type of polio, or many. And they didn’t know how to grow poliovirus safely, and in large enough quantities, to produce vaccines.

Also, researchers were divided over whether a “live-virus” vaccine or a “killed-virus” vaccine would be more effective. Most virologists believed a live-virus vaccine would stimulate higher antibody levels in the blood and create a lasting immunity. Advocates of the killed-virus vaccine believed it could be just as effective, and would eliminate any risk that someone receiving an immunization could contract polio.

Jonas Salk, a young researcher at the University of Pittsburgh, was one of those who believed a killed-virus vaccine would work. It had, after all, been effective against cholera, typhoid, and diphtheria. From 1949 to 1951, Salk and his team conducted extensive testing on thousands of monkeys, using samples from human polio victims and from monkeys who had contracted the virus after being injected with the human samples. Salk’s work confirmed what had been suspected but not yet proven—all of the identified and tested strains of poliovirus fit into one of three distinct types.

About the same time, John Enders, a researcher at Harvard, figured out how to grow poliovirus that would be safe and could be mass produced. But scientists were still stymied over how the virus was transmitted and traveled through the body. Several prominent researchers had long believed that it entered through the nose and traveled directly to the central nervous system, bypassing the bloodstream. If that was the case, a vaccine that stimulated antibodies in the bloodstream would have done no good.

Two scientists working independently, Dorothy Horstmann at Yale and David Bodian at Johns Hopkins, upended the prevailing thinking with a breakthrough discovery. Previous researchers had been unable to detect poliovirus in the blood because they were not looking for it soon enough. Horstmann and Bodian discovered that the poliovirus is in the bloodstream for only a brief period of incubation before the body’s immune system creates antibodies that destroy it.

Salk was relentless in his pursuit of a vaccine. He began human trials against the backdrop of the worst outbreak of polio on record in the U.S.—57,000 cases in 1952. By the spring of 1954, more than 1.3 million children had taken part in the largest vaccine trial in history. It took a year for the results to be reported, and when they were, church bells tolled, factory whistles rung, and then-President Dwight Eisenhower—a war hero—broke down in tears.

Although not 100 percent effective, the Salk vaccine was considered a huge success and a great relief for an edgy nation. In 1956, the number of polio cases in the U.S. dropped by 50 percent compared to the year before, and by another 50 percent the following year.

Meanwhile, Sabin was about to undertake the largest medical experiment in world history—a live-virus vaccine administered to 10 million children in Russia. It, too, proved a success. Considered more effective and easier to administer than the Salk vaccine, Sabin’s oral vaccine won out by 1963.

Oshinsky’s narrative ends at about this point, but the quest to completely eradicate polio is still ongoing. In 1987, the World Health Organization launched a global initiative to eradicate polio worldwide. Since that time, about 2.5 billion children have been vaccinated, and the number of polio cases has decreased by 99 percent. Last year there were fewer than 1,500 cases in just four countries—India, Nigeria, Pakistan, and Afghanistan.

While this is fantastic progress, the last remaining cases pose a serious danger. If not completely eliminated, polio will spread back into countries where it has previously been eradicated, killing and paralyzing perhaps hundreds of thousands of children.

The foundation is deeply involved in this final push, and I am personally committed to doing what I can to rid the world of this dreaded disease once and for all.

I recently came across a book that tells the amazing story of Jim Grant, whose influence in making vaccines widely available in the developing world is credited with saving the lives of 25 million children.

Because of the work the foundation is doing on vaccine-preventable diseases, I’ve read quite a bit about the history of global immunization. But until I read Jim Grant—UNICEF Visionary (an out-of-print book available for free download), I didn’t appreciate what a remarkable visionary and results-driven leader he was. I talk more about the impact of Jim Grant’s contributions in the foundation’s annual letter.

Grant was executive director of UNICEF—the United Nations Children’s Fund—from 1980 to 1995. Prior to that time, UNICEF was already well regarded for its global work—begun in the aftermath of World War II—preventing epidemics and malnutrition among children. In 1965, for example, UNICEF was awarded the Nobel Peace Prize.

But when Grant became head of UNICEF, he saw an opportunity to address a problem that was not high on the priority list of world leaders or international development organizations. At the time, about 14 million children were dying every year of readily preventable illnesses such as measles, tetanus, whooping cough, pneumonia and diarrheal disease. Virtually all of the deaths were occurring in the developing world; Europe and North America had mostly conquered the diseases with low-cost means of prevention or cure developed in the first half of the 20th century.

Grant decided to focus UNICEF’s mission on halving child deaths in the developing world through a massive effort to introduce the same immunizations already available in developed countries, along with other highly-effective low-cost strategies, such as packets of oral rehydration salts for people suffering from diarrheal disease, educating women about the benefits of breast feeding, and monitoring the growth of children. Collectively, these efforts were known as UNICEF’s Child Survival and Development Revolution.

Although we still face many difficulties today getting vaccines to the people who need them, the challenges Grant faced were an order of magnitude greater. No organization had ever tried tackling a global health issue on such a large scale and there were many skeptics, including within UNICEF.

But as Peter Adamson, who worked closely with Grant, writes in one of the book’s chapters, “…who could not be struck by the sheer unforgiveableness of millions upon millions of children dying…when the means to prevent it were at hand.”

Grant talked to anyone who would listen—political leaders, religious leaders, business leaders, educators, the media, NGOs, even the military and police. Repeatedly, he made the point that 40,000 children a day were dying unnecessarily.

In the midst of a civil war in El Salvador, Grant managed to get the government and guerilla leaders to agree to multiple cease fires so children could safely be immunized. (He facilitated similar “periods of tranquility” in wars in Lebanon, Sudan and Iraq.) When Rajiv Gandhi became prime minister of India after the assassination of his mother, Indira Gandhi, Grant persuaded him to make the immunization of India’s children a living memorial to his mother. In Colombia, more than 800,000 children were immunized three times in a three-month period, raising that country’s immunization rate to 75 percent. In Turkey, school teachers were asked to end their vacations three weeks early so they could mobilize their villages. Immunization levels increased from 20 percent to 84 percent.

By the mid-1980s the percentage of children in the developing world who were immunized doubled to 40 percent and prominent organizations like the World Health Organization and Rotary International had joined the effort, providing scientific advice, training, funding and volunteers.

Amazingly, Grant’s target of over 70 percent immunization in the developing world was achieved by 1990. In that year alone, 100 million children in 150 countries were immunized six or more times. It was, Grant said, the largest effort of peacetime mobilization to that point in history.

Grant’s work is especially inspirational when you realize that he achieved success despite a world recession and global debt crisis in the 1980s. We can draw lessons from his leadership now, in our own tough economic times.

By creating a global constituency for children, getting people to focus on specific goals, and creating effective program delivery and measurement systems, Jim Grant literally saved millions of children’s lives.

I have read a number of books this year by Vaclav Smil, a prolific author and professor at the University of Manitoba who has conducted interdisciplinary research on energy, the environment, population, food production and other important topics. Energy Myths and Realities: Bringing Science to the Energy Policy Debate, examines the various predictions that have been made in the past and are still being made about energy use. Most of these predictions are overly optimistic about how quickly things can change and about the effectiveness of particular approaches. Although Smil remains hopeful in the long run, he clearly thinks we will do a better job if we are realistic about the challenges we face.

My favorite Smil book, Creating the Twentieth Century (and its companion, Transforming the Twentieth Century) chronicles the inventions of the last 150 years. It is quite positive because it focuses on innovation and how innovation has advanced society.

Energy Myths and Realities has a more somber tone because it chronicles so many instances of naïve predictions. (Underscoring this point, the book includes a front piece quoting Publius Terentius Afer, a playright in the ancient Roman Republic, who said: “Men believe what they want to believe.”) Some readers may find Smil’s unrelenting criticism of these misguided thoughts a bit tough, but it is important for us to study these mistakes. If we think solving energy problems is easy we will not invest enough to bring low cost power to the poor and we will not take the necessary actions to avoid climate disaster.

I recommend this book to everyone who spends time working on energy issues, not to cheer them up but to help them have a stronger framework for evaluating energy promises. Smil is able to prove that even if we do our best and innovation is amazing, real change will still take at least 20 years. To me, the long lead times and uncertainties involved in bringing new sources of energy online underscore the importance of pursuing many different paths.

Smil brings a strong historical perspective in his books. It is fascinating that in the early 1900s, many observers thought the internal combustion engine would lose out to steam powered cars or electric cars. However, the economics of gasoline with its high energy density and the difficulty of making cheap batteries helped it win out. Rudolf Diesel, who invented the Diesel engine during the 1890s, actually committed suicide in 1913 because he didn’t think his invention would be successful. In fact, it went on to dominate the large marine and truck market within four decades after his death and much later (by the 1990s) it took a significant share of the European automotive market.

I agree with Smil that nuclear-powered electricity may have a significant role to play in the future. (I’m involved in a company—TerraPower—that is working on a type of a fast reactor we expect will have good economics.) But there are many challenges that must be addressed with nuclear around cost, safety, security of materials, and waste disposal. Although I believe there’s a good possibility that innovation can address these issues, we shouldn’t pursue this option alone.

Smil is appropriately tough on the ethanol crowd. This is one energy approach that is unlikely to ever have a significant impact due to fundamental problems. The fact that the U.S. has subsidized this activity at a cost of $5 billion to $7 billion per year—even as it raises the cost of food—is incredible. The U.S. won’t allow foreign ethanol to get the same tax credit, which suggests that the policy is not really focused on the energy benefits of ethanol. A large lobby, which now extends even beyond the corn farmers, manages to keep the policy intact. There are some biofuels approaches that might be better, but even with those there are lots of problems to be solved.

In his other books, Smil opened my eyes to the challenges of many of the new energy technologies by showing their limited energy density. If you compare renewable energy technologies with current power plants fueled by fossil fuels, they are 10 to 100 times less power-dense. This doesn’t mean renewables won’t succeed, but there are a lot of variables to consider, such as weather conditions that affect the predictability of energy generation and the lifespan of equipment.

Smil does a great job explaining why sequestering a large percentage of CO2 emissions won’t ever be easy and is certainly not achievable at large scale in the next several decades. There will be more than 500 billion tons of CO2 generated between 2010 and 2025. This is over 10,000 times more volume than is available in the current experimental carbon sequestration storage projects.

The long term storage challenge will likely require governments to assume responsibility for monitoring and liability. Until a government shows a willingness to do this, I don’t think private industry should risk a lot of money on an effort along these lines. This is a case where the difficulties are understated partly because anyone who has a stake in hydrocarbons may be biased towards this solution since it seems to preserve their current investments, or at least delay any substitution.

Smil is tough on the Gore view that a transition was possible within a 10 year period. He is also very tough on two Scientific American articles that made it seem like it was going to be very easy to switch to renewable sources. I agree with Smil that this thinking erodes the willingness of the public to allow a carbon tax of some kind to be put in place or to fund more basic research and development, which I think is important. I am part of a group called the American Energy Innovation Council that has recommended more government spending on R&D to go along with strong carbon reduction policies.

Smil is careful to point out that energy technologies can’t advance at the rate that microprocessor chips have over the last several decades. To see how different the energy world is from chips and computers, one only need look at the limited improvements in batteries and various types of engines. When people look at the true cost of solar, the challenges of installation and bad weather in the field are often ignored. Smil does a good job of explaining how the figures used for renewable energy installations report peak power output, so you have to divide that by the fraction of the day the energy is available to compare it to plants like nuclear plants that are available over 90% of the time. Because renewables are intermittent, you have to have either a backup way of generating the power and have fully funded that, or you have to have a large scale storage solution which has not been invented and may not be for several decades.

Although Smil focuses mostly on predictions in the energy sector that erred on engineering and cost, we also have to get the regulations and incentives right. It is very difficult to design the right incentives for reliability, transmission, storage and waste. The example of Yucca mountain where the U.S. government promised to solve the nuclear waste problem, spent $9 billion and then cancelled the projects seemingly for political reasons, is concerning. Likewise, it is instructive that the way that the California electricity market was “deregulated” in order to reduce electricity prices actually led to huge price increases. Energy networks involving renewable sources are far more complex than today’s energy networks and any piece that is not handled well leads to a loss of power.

Smil points out that not all projections for the future are overly optimistic. Sometimes a new development like shale gas (natural gas in coal shale formations) comes along and surprises people on the upside. I’m also encouraged by the fact that more engineers and entrepreneurs are working on energy solutions all over the globe than at any time in the past, and they are empowered with better scientific understanding, better modeling tools, and by the ability to share information with each other. Of course, even these positive surprises take decades before they make a difference because of the gigantic scale of the global energy economy.

I don’t view Energy Myths and Realities as a doom and gloom book. It is sobering about the mistakes that have been made but Smil ends by listing a number of lessons that come out of the mistaken predictions of the past, all of which I agree with. I think this book will contribute to better energy policies, which is critically important.

Vaclav Smil has written another important book on energy which is quite amazing. Although there are a lot of important books about energy, as an author Smil is in a class by himself in terms of breadth and depth.

His latest book, Energy Transitions: History, Requirements, Prospects, is only about 175 pages and very readable, although like all of Smil books you have to be comfortable with lots of numbers, since the topic requires them. The various units that energy and power are measured in can often confuse things.

In Energy Transitions, Smil explains the third great energy transition, which occurred over the last several hundred years and included the shift from wood to coal, and the rise of oil and natural gas. As he notes, this transition from biomass to fossil fuels “has been the very essence of modernization.” The first great energy transition was the mastery of fire and the second was associated with the move from foraging to sedentary crop raising and domestication of animals. This third transition really only got going in the late 19th century and did not affect most of humanity until well into the 20th century.

Smil computes the relative energy generated by humans and animals, and early “inanimate” energy technology such as wind power and water power before steam engines came along. And he shows what a small percentage of energy was produced by these inanimate technologies until the late 1800’s, except in the UK.

For each fuel type and each big application Smil explains the key breakthroughs. For natural gas it included new steel alloys, better welding, better pipe-laying, and new compressors invented after World War II. Smil points out that the time between the invention of a new energy technology and its widespread use is usually many decades. In the case of liquefied natural gas, for example, it was almost 100 years.

One section of the book discusses how energy transitions varied in different countries. For example, the Netherlands used its peat resources and wind for early energy intensification. The U.S. was slow to switch to coal – with coal surpassing wood as a primary fuel source only in the 1890’s. Although each of these countries faced very different circumstances in the evolution of their energy technologies, globalization means that our energy challenges going forward are shared.

In the final pages of the book Smil talks about what to expect from the fourth great energy transition, which we have just started. He shows that despite the desire for change “neither its pace not its compositional and operational details are yet clear.”

Smil makes clear the challenges involved in making renewable sources anywhere near as cheap as today’s high carbon energy. He describes the much lower power density of renewable sources and the challenges associated with location, intermittency, storage, and transmission. The intermittency/storage point is one I think he could have made even stronger. Even though this section overlaps with the other energy book he published this year (Energy Myths and Realities) it is still very much worth reading.

The book ends with Smil expressing disappointment that the U.S. and other wealthy countries have not done more to reduce energy usage. This is an important point, but I wish he had ended with a more detailed discussion of the fourth transition. While some people might not agree with everything Smil says, he has certainly taught me that, even with needed improvements in energy efficiency, it will be very difficult to get adequate amounts of cheap, carbon-neutral power to the poor very quickly, critical as that goal is.

While traveling last week to Antarctica, I had a chance to read a book recommended by our foundation’s agricultural development group, Tomorrow's Table: Organic Farming, Genetics, and the Future of Food by Pamela Ronald and Raoul Adamchak.

This is an important book for anyone who wants to learn about the science of seeds and the challenges faced by farmers. It’s only 167 pages, and includes personal stories that give you a sense of the authors as people and how strongly they feel about farming, food and the environment. I think anyone who reads this book will be convinced of the authors’ sincerity and intelligence – even if, like me, you never try any of the cool-sounding recipes.

Whenever I read about farming, I’m reminded how tough it is. Between the weather, weeds, viruses, insects and other pests, farming is a constant struggle, always posing new challenges. A city boy like me can think of it as putting a seed in the ground and waiting for nice stuff to grow. Wrong.

Tomorrow’s Table is a real education on the many choices farmers today must make regarding seeds. It’s very good in explaining genetically engineered seed, how it’s used today (mostly to help plants fight off insects and tolerate herbicide) and how it will be used in the future (to increase disease resistance, drought tolerance, vitamin content and crop yields, for example). The book separates out clearly the issues of how to make sure new seeds are safe, how to price them and how to treat them as intellectual property.

I gained an understanding of the history of organic farming and learned about some of the very clever ways organic farmers control pests. Compared with conventional agriculture, many organic techniques can be more cost effective for poor farmers. I agree with the authors that we will need the best ideas from "organic" thinkers and from scientists – including genetic engineers – to feed the world and help the poorest.

Of course, there are more approaches available to farmers than just organic or biotech. Most of the world’s food is grown with conventional agricultural techniques such as improved seeds, fertilizer and irrigation. The trick is finding the best combination of all of these approaches.

I certainly recommend this book to people who are curious about the future of agriculture and the controversies around it. Many other food books exalt localism and tradition (i.e., lack of new science) as almost religious values. I think some go overboard with their negative views of modern farming, giving very little thought to the productivity increases that poor farmers need - and that the world needs - in order to feed itself, while coping with climate change and evolving threats from plant disease and pests.

I wish Tomorrow’s Table discussed the problem of underinvestment in agricultural research. But the authors’ personal involvement in what they do write about gives the book a note of deep sincerity. That may help get people who are skeptical or confused about new science, including biotechnology, to see that it has an important role to play.

In the last few months I have read three books by Vaclav Smil that I highly recommend. He also recently visited our offices and opened my eyes to new ways to think about solving our energy and environmental issues.

If you are interested in learning more about the foundation of our energy system, the issues we face, and opportunities to address them, I highly recommend his books, even though some are slightly technical.

I also recommend Sustainable Energy - without the hot air by David MacKay, which I discuss here. There’s also a video of MacKay’s that I liked a lot.

Here are two books that I have previously read by Smil: Energy at the Crossroads: Global Perspectives and Uncertainties is an excellent book that explains the history of energy and the challenges we face.

Global Catastrophes and Trends: The Next 50 Years is also great.

The ones I just got around to are:

Enriching the Earth: Fritz Habery, Carol Bosch and the Transformation of World Food Production is a must read for anyone who wants to know about fertilizer. It is very well written and explains the science very well. He makes a strong case for how important nitrogen is. Even for someone who already knows a lot, his synthesis here is fantastic. He not only gives the history, he also talks about the future and what can be done. As usual, he is incredibly educational with lots of numbers. He explains the various sources of nitrogen for various crops. His math suggests that although over half of fertilizer is wasted, in most cases something like 30% ends up in the crops.

Energies: An Illustrated Guide to the Biosphere and Civilization explains a lot about energy uses and what has changed over time. He goes from cells to engines.

The Earth’s Biosphere: Evolution, Dynamics and Change. I am just reading this one.

If you don’t have time to read any of Smil’s books, there’s a great video that I would recommend.

The noted climate researcher Ken Caldeira suggested I read Sustainable Energy - without the hot air by David MacKay. I’m grateful for his recommendation.

The book is available for free at: www.withouthotair.com where you can also buy it in hard copy.

There’s also a great video of MacKay that I really like.

I agree with Ken that this is one of the best books on energy that has been written. If someone is going to read just one book I would recommend this one. It isn’t an easy read but that’s because you learn so much. Even after you read this book you will want to keep it around since whenever you read about a new development in energy technology, the framework in this book will help you understand how important it is and where it fits in.

If someone wants an overall view of how energy gets used, where it comes from, and the challenges in switching to new sources, this is the book to read. The book isn’t a global warming book per se but it shows various ways to change our energy generation so it emits very little CO2.

The book is very numeric which is appropriate. MacKay uses kilowatt-hours-per-person-per-day to discuss everything. He has a great section that explains how articles about energy use different measures like number of households powered and how all these measures obscure the overall energy equation. His use of a common metric is critical to giving the reader a clear understanding of how we might get our energy inputs to match our overall energy needs in the future.

To avoid overwhelming the main text with formulas, MacKay uses the appendix to explain why cars, planes, or houses use as much energy as they do and how to figure out the potential energy from various new approaches like wind and tides.

The focus is on educating the reader rather than promoting a point of view. MacKay’s strongest point is that any plan for the future has to have enough energy sources to meet the demand. He thinks people ought to have a numeric sense of how their energy consumption adds up. He gives a lot of examples of things like the energy used for making grocery store plastic bags that won’t have a significant impact on reducing CO2 but that get far more attention than critical issues like how to dramatically improve the transmission network.

He focuses on the UK in early chapters but then extends that to the rest of the world. You might learn a bit more about British inlets that can be used for pumped water storage and the tides around Britain than you expected to but that is minor.

The book explains all the big categories of energy usage with great clarity and he explains what can be done to reduce usage in all of these areas. In Europe, for example, people use 125Kwh per day per person, including 40Kwh for transportation, 40Kwh for heating and cooling, and 45Khw to generate the 18Kwh of electricity they use each day.

MacKay thinks that new designs and electric engines can reduce transportation to 20Kwh and heating and cooling can be cut to 30kwh per person per day. He leaves direct electrical usage at 18Kwh per person per day since the improvements in areas like lighting will be offset by new uses of electricity. MacKay is very convincing that we won’t see usage fall much more than this despite all the great ideas for efficiency improvements.

Americans use 250Kwh per person per day so there are even more opportunities for efficiency, but still not enough to solve the problem of future energy sources.

The area where there is great uncertainty is what the sources of energy will be in the future. MacKay provides five different scenarios which vary according to how much solar, clean coal, nuclear, or wind they use.

MacKay does a great job of explaining the challenges that come with sources that don’t provide energy on demand 24 hours a day. Whenever you hear someone talk about the power output of a wind farm they are talking about the output during the time the wind blows which is typically one-third of the day. Solar is similar. As long as we are getting a modest amount of our power from these sources, other sources can be adjusted to make the total work out around the clock. MacKay explains that there is no magic storage technology today that would allow you to store extra power for the rest of the day. He talks about how costly and large the storage would be for the UK to get most of its energy from renewable sources.

It is possible that there will be a huge breakthrough in battery technology to help with this problem but it would be unwise to count on that. The scenario MacKay gives where electric car batteries are used for storage doesn’t seem realistic to me since batteries can only be cycled a finite number of times before they have to be replaced and it would take an amazing grid. He doesn’t mention the possibility of using rocks in connection with solar thermal energy plants to enable them to provide power over a 24-hour period.

Society is incredibly dependent on having a reliable power supply. It is easy to stockpile coal at a coal plant. The cost to having the same guaranteed availability for wind and sun would be very high.

MacKay also does a great job of explaining that changing to energy sources that only work well in specific locations requires a lot of investment and permitting for transmission lines. Today’s fuels can be moved from place to place but sun and wind cannot.

MacKay has one chapter focused on global warming and CO2. He talks about a scheme for capturing CO2 from the atmosphere which is worth exploring. I was surprised he didn’t mention geoengineering techniques to delay or reduce the effects of global warming. He also didn’t explain enough about other gases that cause global warming.

As you look at the possibilities for the UK you see that there is a huge question about whether it is reasonable to count on a high percentage of the power coming from the deserts of North Africa using solar photovoltaic or solar thermal technology. It can be done but does it create unaffordable political and reliability risk? The book offers only one plan that doesn’t count on nuclear, clean coal, or acquiring most of the power from a foreign country. Of the five scenarios, I think it is the least realistic since it uses so much wind and requires gigantic levels of storage.

One place where MacKay does have a strong point of view is that the amount of government R&D going into energy is pathetically low. The UK is spending less than £0.2 per person per year. The United States has raised its number but it is still way too low. If people understood that the only way to reduce CO2 emission by 80% is to have a large number of research breakthroughs, then perhaps this would change. Even the most optimistic scenarios for conservation will not get to 80% as long as cars, heating, and electricity generate CO2.

If people think that raising energy prices a little bit or just consuming a bit less will solve this problem, we will never achieve the required reductions. Regulations requiring electricity plants to move to low CO2 emission over a 40 year period would send a stronger market signal to power plant makers than any of the cap and trade systems that are likely to get implemented.

I was thrilled to see a book that is scientific, numeric, broad, open-minded, and well written on a topic where a lot of narrow, obscure, non-numeric writing confuses the public. People need to really understand what is going on and then be part of the process of moving the world to a new energy infrastructure.