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Hunger

Climates differ and plants vary, but the basic rule of thumb for staple cereal crops grown at optimal temperature is that for every degree of warming, yields decline by 10 percent. Some estimates run higher. Which means that if the planet is five degrees warmer at the end of the century, when projections suggest we may have as many as 50 percent more people to feed, we may also have 50 percent less grain to give them. Or even less, because yields actually decline faster the warmer things get. And proteins are worse: it takes eight pounds of grain to produce just a single pound of hamburger meat, butchered from a cow that spent its life warming the planet with methane burps.

Globally, grain accounts for about 40 percent of the human diet; when you add soybeans and corn, you get up to two-thirds of all human calories. Overall, the United Nations estimates that the planet will need nearly twice as much food in 2050 as it does today—and although this is a speculative figure, it’s not a bad one. Pollyannaish plant physiologists will point out that the cereal-crop math applies only to those regions already at peak growing temperature, and they are right—theoretically, a warmer climate will make it easier to grow wheat in Greenland. But as a pathbreaking paper by Rosamond Naylor and David Battisti pointed out, the tropics are already too hot to efficiently grow grain, and those places where grain is produced today are already at optimal growing temperature—which means even a small warming will push them down a slope of declining productivity. The same, broadly speaking, is true for corn. At four degrees of warming, corn yields in the United States, the world’s top producer of maize, are expected to drop by almost half. Predicted declines are not quite as dramatic in the next three biggest producers—China, Argentina, Brazil—but in each case the country would lose at least a fifth of its productivity.

A decade ago, climatologists might have told you that although direct heat undermined plant growth, the extra carbon in the atmosphere would have the opposite effect—a kind of airborne fertilizer. The effect is strongest on weeds, though, and does not seem to hold for grain. And at higher concentrations of carbon, plants grow thicker leaves, which sounds innocuous. But thicker leaves are worse at absorbing CO2, an effect that means, by the end of the century, as much as 6.39 billion additional tons in the atmosphere each year.

Beyond carbon, climate change means staple crops are doing battle with more insects—their increased activity could cut yields an additional 2 to 4 percent—as well as fungus and disease, not to mention flooding. Some crops, like sorghum, are a bit more robust, but even in those regions where such alternatives have been a staple, their production has diminished recently; and while grain breeders have some hope that they can produce more heat-tolerant strains, they’ve been trying for decades without success. The world’s natural wheat belt is moving poleward by about 160 miles each decade, but you can’t easily move croplands north a few hundred miles, and not just because it’s difficult to suddenly clear the land occupied now by towns, highways, office parks, and industrial installations. Yields in places like remote areas of Canada and Russia, even if they warmed by a few degrees, would be limited by the quality of soil there, since it takes many centuries for the planet to produce optimally fertile dirt. The lands that are fertile are the ones we are already using, and the climate is changing much too fast to wait for the northern soil to catch up. That soil, believe it or not, is literally disappearing—75 billion tons of soil lost each year. In the United States, the rate of erosion is ten times as high as the natural replenishment rate; in China and India, it is thirty to forty times as fast.

Even when we try to adapt, we move too slowly. Economist Richard Hornbeck specializes in the history of the American Dust Bowl; he says that farmers of that era could conceivably have adapted to the changing climate of their time by cultivating different crops. But they didn’t, lacking credit to make the necessary investments—and were therefore unable to shake inertia and ritual and the rootedness of identity. So instead the crops died out, in cascading waves crashing through whole American states and all the people living in them.

As it happens, a similar transformation is unfolding in the American West right now. In 1879, the naturalist John Wesley Powell, who spent his downtime as a soldier during the Battle of Vicksburg studying the rocks that filled the Union trenches, divined a natural boundary running due north along the 100th meridian. It separated the humid—and therefore cultivatable—natural farmland of what became the Midwest from the arid, spectacular, but less farmable land of the true West. The divide ran through Texas, Oklahoma, Kansas, Nebraska, and the Dakotas, and stretches south into Mexico and north into Manitoba, Canada, separating more densely populated communities full of large farms from sparser, open land that was never truly made valuable by agriculture. Since just 1980, that boundary has moved fully 140 miles east, almost to the 98th parallel, drying up hundreds of thousands of square miles of farmland in the process. The planet’s only other similar boundary is the one separating the Sahara desert from the rest of Africa. That desert has expanded by 10 percent, too; in the winter, the figure is 18 percent.

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The privileged children of the industrialized West have long laughed at the predictions of Thomas Malthus, the British economist who believed that long-term economic growth was impossible, since each bumper crop or episode of growth would ultimately produce more children to consume or absorb it—and as a result the size of any population, including that of the planet as a whole, was a check against material well-being. In 1968, Paul Ehrlich made a similar warning, updated for a twenty-first-century planet with many times more people on it, with his widely derided The Population Bomb, which proposed that the economic and agricultural productivity of the earth had already reached its natural limit—and which was published, as it happened, just as the productivity gains from what’s called the “green revolution” were coming into focus. That term, which today is sometimes used to describe advances in clean energy, first arose to name the incredible boom in agricultural yields produced by innovations in farming practices in the middle of the twentieth century. In the half century since, not only has the world’s population doubled but the fraction of people living in extreme poverty has fallen by a factor of about six—from just more than half of humanity to 10 percent. In the world’s developing countries, undernourishment has dropped from more than 30 percent in 1970 to close to 10 percent today.

These developments counsel sanguinity in the face of all kinds of environmental pressures, and in his recent book on the meaning of the twentieth-century agricultural boom, the writer Charles Mann divides those who respond to the seeming challenge of resource scarcity with reflexive optimism, whom he calls “wizards,” from those who see collapse always around the corner, whom he calls “prophets.” But though the green revolution seems almost too perfectly conceived and executed to refute Ehrlich’s alarmism, Mann himself is not sure what the lessons are. It may yet be a bit early to judge Ehrlich—or perhaps even his godfather, Malthus—since nearly all of the astonishing productivity gains of the last century trace back to the work of a single man, Norman Borlaug, perhaps the best argument for the humanitarian virtue of America’s imperial century. Born to Iowa family farmers in 1914, he went to state school, found work at DuPont, and then, with the help of the Rockefeller Foundation, developed a new collection of high-yield, disease-resistant wheat varieties that are now credited with saving the lives of a billion people worldwide. Of course, if those gains were a onetime boost—engineered, in large part, by a single man—how comfortably can we count on future improvements?

The academic term for the subject of this debate is “carrying capacity”: How much population can a given environment ultimately support before collapsing or degrading from overuse? But it is one thing to consider what might be the maximum yield of a particular plot of earth and another to contemplate how fully that number is governed by environmental systems—systems far larger and more diffusely determined than even an imperial wizard like Borlaug could reasonably expect to command and control. Global warming, in other words, is more than just one input in an equation to determine carrying capacity; it is the set of conditions under which all of our experiments to improve that capacity will be conducted. In this way, climate change appears to be not merely one challenge among many facing a planet already struggling with civil strife and war and horrifying inequality and far too many other insoluble hardships to iterate, but the all-encompassing stage on which all those challenges will be met—a whole sphere, in other words, which literally contains within it all of the world’s future problems and all of its possible solutions.

Curiously, maddeningly, these can be the same. The graphs that show so much recent progress in the developing world—on poverty, on hunger, on education and infant mortality and life expectancy and gender relations and more—are, practically speaking, the same graphs that trace the dramatic rise in global carbon emissions that has brought the planet to the brink of overall catastrophe. This is one aspect of what is meant by the term “climate justice.” Not only is it undeniably the case that the cruelest impacts of climate change will be borne by those least resilient in the face of climate tragedy, but to a large degree what could be called the humanitarian growth of the developing world’s middle class since the end of the Cold War has been paid for by fossil-fuel-driven industrialization—an investment in the well-being of the global south made by mortgaging the ecological future of the planet.

This is one reason that our global climate fate will be shaped so overwhelmingly by the development patterns of China and India, who have the tragic burden of trying to bring many hundreds of millions more into the global middle class while knowing that the easy paths taken by the nations that industrialized in the nineteenth and even twentieth centuries are now paths to climate chaos. Which is not to say they won’t follow them anyway: by 2050, milk consumption in China is expected to grow to triple the current level, thanks to the changing, West-facing tastes of its emerging consumer classes, a single-item boom in a single country that is expected, all by itself, to increase global greenhouse-gas emissions from dairy farming by about 35 percent.

Already, global food production accounts for about a third of all emissions. To avoid dangerous climate change, Greenpeace has estimated that the world needs to cut its meat and dairy consumption in half by 2050; everything we know about what happens when countries get wealthier suggests this will be close to impossible. And turning away from milk is one thing; turning down cheap electrification, automobile culture, or the protein-heavy diets the world’s wealthy rely on to stay thin are much bigger asks. In the postindustrial West, we try not to think about these bargains, which have benefited us so enormously. When we do, it is often in the guilty spirit of what critic Kris Bartkus has memorably called “the Malthusian tragic”—namely, our inability to see any remaining innocence in the quotidian life of the well-to-do West, given the devastation that wealth has imposed on the world of natural wonder it conquered and the suffering of those, elsewhere on the planet, left behind in the race to endless material comforts. And asked, functionally, to pay for them.

Of course, most have not embraced that tragic, or self-pitying, view. A state of half-ignorance and half-indifference is a much more pervasive climate sickness than true denial or true fatalism. It is the subject of William Vollmann’s grand, two-part Carbon Ideologies, which opens—beyond the epigraph “A crime is something someone else commits,” from Steinbeck—like this: “Someday, perhaps not long from now, the inhabitants of a hotter, more dangerous and biologically diminished planet than the one on which I lived may wonder what you and I were thinking, or whether we thought at all.” For much of the book’s prologue, he writes in a past tense rendered from an imagined, devastated future. “Of course we did it to ourselves; we had always been intellectually lazy, and the less asked of us, the less we had to say,” he writes. “We all lived for money, and that is what we died for.” —

Drought may be an even bigger problem for food production than heat, with some of the world’s most arable land turning quickly to desert. At 2 degrees of warming, droughts will wallop the Mediterranean and much of India, and corn and sorghum all around the world will suffer, straining global food supply. At 2.5 degrees, thanks mostly to drought, the world could enter a global food deficit—needing more calories than the planet can produce. At 3 degrees, there would be further drought—in Central America, Pakistan, the western United States, and Australia. At 5 degrees, the whole earth would be wrapped in what the environmentalist Mark Lynas calls “two globe-girdling belts of perennial drought.” Precipitation is notoriously hard to model in detail, yet predictions for later this century are basically unanimous: both unprecedented droughts and unprecedented flood-producing rains. By 2080, without dramatic reductions in emissions, southern Europe will be in permanent extreme drought, much worse than the American Dust Bowl ever was. The same will be true in Iraq and Syria and much of the rest of the Middle East; some of the most densely populated parts of Australia, Africa, and South America; and the breadbasket regions of China. None of these places, which today supply much of the world’s food, would be reliable sources going forward. As for the original Dust Bowl: the droughts in the American plains and Southwest would not just be worse than in the 1930s, a 2015 NASA study predicted, but worse than any droughts in a thousand years—and that includes those that struck between 1100 and 1300, which dried up all the rivers east of the Sierra Nevada mountains and may have been responsible for the death of the Anasazi civilization.

Remember, even with the remarkable gains of the last decades, we do not presently live in a world without hunger. Far from it: most estimates put the number of undernourished at 800 million globally, with as many as 100 million hungry because of climate shocks. What is called “hidden hunger”—micronutrient and dietary deficiencies—is considerably higher, affecting well over 1 billion people. The spring of 2017 brought an unprecedented quadruple famine to Africa and the Middle East; the United Nations warned that those separate starvation events in Somalia, South Sudan, Nigeria, and Yemen could kill 20 million that year. That was a single year in a single region. Africa is today straining to feed about 1 billion people, a population expected to quadruple over the course of the twenty-first century to 4 billion.

One hopes these population booms will bring their own Borlaugs, ideally many of them. And already there are some hints of possible technological breakthroughs: China has invested in truly customized farming strategies to boost productivity and cut the use of greenhouse-gas-producing fertilizer; in Britain, a “soil-free startup” announced its first “harvest” in 2018; in the United States, you already hear about the prospects for vertical farming, which saves farmland by stacking crops indoors; and lab-grown protein, which does the same by culturing meats inside test tubes. But these remain vanguard technologies, distributed unequally and, being so expensive, unavailable for now to the many who are most in need. A decade ago, there was great optimism that GMO crops could produce another green revolution, but today gene modification has been used mostly to make plants more resistant to pesticides, pesticides manufactured and sold by the same companies engineering the crops. And cultural resistance has grown so rapidly that Whole Foods now advertises its house brand of seltzer as “GMO-free sparkling water.” It is far from clear how much benefit even those able to take advantage of vanguard techniques will be able to reap. Over the past fifteen years, the iconoclastic mathematician Irakli Loladze has isolated a dramatic effect of carbon dioxide on human nutrition unanticipated by plant physiologists: it can make plants bigger, but those bigger plants are less nutritious. “Every leaf and every grass blade on earth makes more and more sugars as CO2 levels keep rising,” Loladze told Politico, in a story about his work headlined “The Great Nutrient Collapse.” “We are witnessing the greatest injection of carbohydrates into the biosphere in human history—[an] injection that dilutes other nutrients in our food supply.” Since 1950, much of the good stuff in the plants we grow—protein, calcium, iron, vitamin C, to name just four—has declined by as much as one-third, a landmark 2004 study showed. Everything is becoming more like junk food. Even the protein content of bee pollen has dropped by a third.

The problem has gotten worse as carbon concentrations have gotten worse. Recently, researchers estimated that by 2050 as many as 150 million people in the developing world will be at risk of protein deficiency as the result of nutrient collapse, since so many of the world’s poor depend on crops, rather than animal meat, for protein; 138 million could suffer from a deficiency of zinc, essential to healthy pregnancies; and 1.4 billion could face a dramatic decline in dietary iron—pointing to a possible epidemic of anemia. In 2018, a team led by Chunwu Zhu looked at the protein content of eighteen different strains of rice, the staple crop for more than 2 billion people, and found that more carbon dioxide in the air produced nutritional declines across the board—drops in protein content, as well as in iron, zinc, and vitamins B1, B2, B5, and B9. Really everything but vitamin E. Overall, the researchers found that, acting just through that single crop, rice, carbon emissions could imperil the health of 600 million people.

In previous centuries, empires were built on that crop. Climate change promises another, an empire of hunger, erected among the world’s poor.