But accusations of individual irresponsibility were a kind of weaponized red herring, as they often are in communities reckoning with the onset of climate pain. We frequently choose to obsess over personal consumption, in part because it is within our control and in part as a very contemporary form of virtue signaling. But ultimately those choices are, in almost all cases, trivial contributors, ones that blind us to the more important forces. When it comes to freshwater, the bigger picture is this: personal consumption amounts to such a thin sliver that only in the most extreme droughts can it even make a difference. Even before the drought, one estimate found that South Africa had nine million people without any access to water for personal consumption at all; the amount of water required to satisfy the needs of those millions is only about one-third the amount of water used, each year, to produce the nation’s wine crop. In California, where droughts are punctuated by outrage over pools and ever-green lawns, total urban consumption accounts for only 10 percent.
In South Africa, eventually, the crisis passed—a combination of aggressive water rationing and the end of the dry season. But you could be forgiven, considering the news coverage of Cape Town, for thinking that the South African city was the first to stare down a Day Zero. In fact, São Paulo did it in 2015, after a two-year drought, limiting water use to twelve hours a day for some residents in an aggressive rationing system that shuttered businesses and forced mass layoffs. In 2008, Barcelona, facing the worst drought the city had seen since Catalonians began keeping records, had to barge in drinking water from France. In southern Australia, the “millennium drought” began with low rainfall in 1996 and continued, through a Death Valley–like trough that lasted eight years, beginning in 2001 and ending only when La Niña rainfall finally relieved the area in 2010. Rice and cotton production in the region fell 99 and 84 percent, respectively. Rivers and lakes shriveled up and wetlands turned acidic. In 2018, in the Indian city of Shimla, once the summertime home of the British Raj, the taps ran dry for weeks in May and June.
And while agriculture is often hit the hardest by shortages, water issues are not exclusively rural. Fourteen of the world’s twenty biggest cities are currently experiencing water scarcity or drought. Four billion people, it is estimated, already live in regions facing water shortages at least one month each year—that’s about two-thirds of the planet’s population. Half a billion are in places where the shortages never end. Today, at just one degree of warming, those regions with at least a month of water shortages each year include just about all of the United States west of Texas, where lakes and aquifers are being drained to meet demand, and stretching up into western Canada and down to Mexico City; almost all of North Africa and the Middle East; a large chunk of India; almost all of Australia; significant parts of Argentina and Chile; and everything in Africa south of Zambia.
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As long as it has had advocates, climate change has been sold under a saltwater banner—melting Arctic, rising seas, shrinking coastlines. A freshwater crisis is more alarming, since we depend on it far more acutely. It is also closer at hand. But while the planet commands the necessary resources today to provide water for drinking and sanitation to all the world’s people, there is not the necessary political will—or even the inclination—to do so.
Over the next three decades, water demand from the global food system is expected to increase by about 50 percent, from cities and industry by 50 to 70 percent, and from energy by 85 percent. And climate change, with its coming megadroughts, promises to tighten supply considerably. In fact, the World Bank, in its landmark study of water and climate change “High and Dry,” found that “the impacts of climate change will be channeled primarily through the water cycle.” The bank’s foreboding warning: that when it comes to the cruelly cascading effects of climate change, water efficiency is as pressing a problem, and as important a puzzle to solve, as energy efficiency. Without any meaningful adaptation in the distribution of water resources, the World Bank estimates, regional GDP could decline, simply due to water insecurity, by as much as 14 percent in the Middle East, 12 percent in Africa’s Sahel, 11 percent in central Asia, and 7 percent in east Asia.
But of course GDP is at best a crude measure of environmental cost. A more eye-opening ledger is kept by Peter Gleick of the Pacific Institute: a simple list of all armed conflicts tied up with water issues, beginning in 3,000 BC with the ancient Sumerian legend of Ea. Gleick lists nearly five hundred water-related conflicts since 1900; almost half of the entire list is since just 2010. Part of that, Gleick acknowledges, is a reflection of the relative abundance of recent data, and part of it is the changing nature of war—conflicts that used to unfold almost exclusively between states are now, in an era where state authority has weakened in many places, likely to spark within states and between groups. The five-year Syrian drought that stretched from 2006 to 2011, producing crop failures that created political instability and helped usher in the civil war that produced a global refugee crisis, is one vivid example. Gleick is personally more focused on the strange war unfolding in Yemen since 2015—technically a civil war, but practically a proxy regional war between Saudi Arabia and Iran, and conceptually a sort of world war in miniature, with American and Russian involvement as well. There, the humanitarian cost has been carried as much by water as by blood; in part because of targeted attacks on water infrastructure, the number of cholera cases grew to one million in 2017, which means in a single year roughly 4 percent of the country contracted the disease.
“There’s a saying in the water community,” Gleick tells me. “If climate change is a shark, the water resources are the teeth.”
Dying Oceans
We tend to see oceans as unfathomable, the closest thing we have on this planet to outer space: dark, forbidding, and, especially in the depths, quite weird and mysterious. “Who has known the ocean?” Rachel Carson wrote in her essay “Undersea,” published twenty-five years before she tackled the desecration of the planet’s land by human hands, and industrial “cure-alls,” in Silent Spring: “Neither you nor I, with our earth-bound senses, know the foam and surge of the tide that beats over the crab hiding under the seaweed of his tide-pool home; or the lilt of the long, slow swells of mid-ocean, where shoals of wandering fish prey and are preyed upon, and the dolphin breaks the waves to breathe the upper atmosphere.”
But the ocean isn’t the other; we are. Water is not a beachside attraction for land animals: at 70 percent of the earth’s surface it is, by an enormous margin, the planet’s predominant environment. Along with everything else it does, oceans feed us: globally, seafood accounts for nearly a fifth of all animal protein in the human diet, and in coastal areas it can provide much more. The oceans also maintain our planetary seasons, through prehistoric currents like the Gulf Stream, and modulate the temperature of the planet, absorbing much of the heat of the sun.
Perhaps “has fed,” “has maintained,” and “has modulated” are better terms, since global warming threatens to undermine each of those functions. Already, fish populations have migrated north by hundreds of miles in search of colder waters—flounder by 250 miles off the American East Coast, mackerel so far from their Continental home that the fishermen chasing them are no longer bound by rules set by the European Union. One study tracing human impact on marine life found only 13 percent of the ocean undamaged, and parts of the Arctic have been so transformed by warming that scientists are beginning to wonder how long they can keep calling those waters “arctic.” And however much sea-level rise and coastal flooding have dominated our fears about the impact of climate change on the planet’s ocean water, there is much more than just that to worry over.
At present, more than a fourth of the carbon emitted by humans is sucked up by the oceans, which also, in the past fifty years, have absorbed 90 percent of global warming’s excess heat. Half of that heat has been absorbed since 1997, and today’s seas carry at least 15 percent more heat
energy than they did in the year 2000—absorbing three times as much additional energy, in just those two decades, as is contained in the entire planet’s fossil fuel reserves. But the result of all that carbon dioxide absorption is what’s called “ocean acidification,” which is exactly what it sounds like, and which is also already burning through some of the planet’s water basins—you may remember these as the place where life arose in the first place. All on its own—through its effect on phytoplankton, which release sulfur into the air that helps cloud formation—ocean acidification could add between a quarter and half of a degree of warming.
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You have probably heard of “coral bleaching”—that is, coral dying—in which warmer ocean waters strip reefs of the protozoa, called zooxanthellae, that provide, through photosynthesis, up to 90 percent of the energy needs of the coral. Each reef is an ecosystem as complex as a modern city, and the zooxanthellae are its food supply, the basic building block of an energy chain; when they die, the whole complex is starved with military efficiency, a city under siege or blockade. Since 2016, as much as half of Australia’s landmark Great Barrier Reef has been stripped in this way. These large-scale die-outs are called “mass bleaching events”; one unfolded, globally, from 2014 to 2017. Already, coral life has declined so much that it has created an entirely new layer in the ocean, between 30 and 150 meters below the surface, which scientists have taken to calling a “twilight zone.” According to the World Resources Institute, by 2030 ocean warming and acidification will threaten 90 percent of all reefs.
This is very bad news, because reefs support as much as a quarter of all marine life and supply food and income for half a billion people. They also protect against flooding from storm surges—a function that offers value in the many billions, with reefs presently worth at least $400 million annually to Indonesia, the Philippines, Malaysia, Cuba, and Mexico—$400 million annually to each. Ocean acidification will also damage fish populations directly. Though scientists aren’t yet sure how to predict the effects on the stuff we haul out of the ocean to eat, they do know that in acid waters, oysters and mussels will struggle to grow their shells, and that rising carbon concentrations will impair fishes’ sense of smell—which you may not have known they had, but which often aids in navigation. Off the coasts of Australia, fish populations have declined an estimated 32 percent in just ten years.
It has become quite common to say that we are living through a mass extinction—a period in which human activity has multiplied the rate at which species are disappearing from the earth by a factor perhaps as large as a thousand. It is probably also fair to call this an era marked by what is called ocean anoxification. Over the past fifty years, the amount of ocean water with no oxygen at all has quadrupled globally, giving us a total of more than four hundred “dead zones”; oxygen-deprived zones have grown by several million square kilometers, roughly the size of all of Europe; and hundreds of coastal cities now sit on fetid, under-oxygenated ocean. This is partly due to the simple warming of the planet, since warmer waters can carry less oxygen. But it is also partly the result of straightforward pollution—a recent Gulf of Mexico dead zone, all 9,000 square miles of it, was powered by the runoff of fertilizer chemicals washing into the Mississippi from the industrial farms of the Midwest. In 2014, a not-atypical toxic event struck Lake Erie, when fertilizer from corn and soy farms in Ohio spawned an algae bloom that cut off drinking water for Toledo. And in 2018, a dead zone the size of Florida was discovered in the Arabian Sea—so big that researchers believed it might encompass the entire 63,700-square-mile Gulf of Oman, seven times the size of the dead zone in the Gulf of Mexico. “The ocean,” said the lead researcher Bastien Queste, “is suffocating.”
Dramatic declines in ocean oxygen have played a role in many of the planet’s worst mass extinctions, and this process by which dead zones grow—choking off marine life and wiping out fisheries—is already quite advanced not only in the Gulf of Mexico but just off Namibia, where hydrogen sulfide is bubbling out of the sea along a thousand-mile stretch of land known as the Skeleton Coast. The name originally referred to the detritus of wrecked ships, but today it’s more apt than ever. Hydrogen sulfide is also one of the things scientists suspect finally capped the end-Permian extinction, once all the feedback loops had been triggered. It is so toxic that evolution has trained us to recognize the tiniest, safest traces, which is why our noses are so exquisitely skilled at registering flatulence.
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And then there is the possible slowdown of the “ocean conveyor belt,” the great circulatory system made up of the Gulf Stream and other currents that is the primary way the planet regulates regional temperatures. How does this work? The water of the Gulf Stream cools off in the atmosphere of the Norwegian Sea, making the water itself denser, which sends it down into the bottom of the ocean, where it is then pushed southward by more Gulf Stream water—itself cooling in the north and falling to the ocean floor—eventually all the way to Antarctica, where the cold water returns to the surface and begins to heat up and travel north. The trip can take a thousand years.
As soon as the conveyor belt became the subject of real study, in the 1980s, there were those oceanographers who worried it might shut down, which would lead to a dramatic disequilibration of the planet’s climate—the hotter parts getting much hotter and the colder parts much colder. A total shutdown would be inconceivably catastrophic, though the impacts look deceptively innocuous on first scan—a colder Europe, more intense weather, additional sea-level rise. Invariably, this is described as the Day After Tomorrow scenario, and it is a strange twist of fate that so forgettable a movie has become the memorable shorthand for this particular worst-case nightmare.
A shutdown of the conveyor belt is not a scenario that any credible scientists worry about on any human timescale. But a slowdown is another matter. Already, climate change has depressed the velocity of the Gulf Stream by as much as 15 percent, a development that scientists call “an unprecedented event in the past millennium,” believed to be one reason the sea-level rise along the East Coast of the United States is dramatically higher than elsewhere in the world. And in 2018, two major papers triggered a new wave of concern over the conveyor belt, technically called Atlantic Meridional Overturning Circulation, which was found to be moving at its slowest rate in at least 1,500 years. This had happened about a hundred years ahead of the schedule of even alarmed scientists and marked what the climate scientist Michael Mann called, ominously, a “tipping point.” Further change, of course, is to come: the transformation of the ocean by warming making these unknown waters doubly unknowable, remodeling the planet’s seas before we ever were able to discover their depths and all the life submerged there.
Unbreathable Air
Our lungs need oxygen, but it is only a fraction of what we breathe, and the fraction tends to decline the more carbon is in the atmosphere. That doesn’t mean we are at risk of suffocation—oxygen is far too abundant for that—but we will nevertheless suffer. With CO2 at 930 parts per million (more than double where we are today), cognitive ability declines by 21 percent.
The effects are more pronounced indoors, where CO2 tends to build up—that’s one reason you probably feel a little more awake when taking a brisk walk outside than you do after spending a long day inside with the windows closed. And it’s also a reason elementary school classrooms have been found, by one study, to already average 1,000 parts per million, with almost a quarter of those surveyed in Texas over 3,000—quite alarming numbers, given that these are the environments we’ve designed to promote intellectual performance. But classrooms are not the worst offenders: other studies have shown even higher concentrations on airplanes, with effects you can probably groggily recall from past experience.
But carbon is, more or less, the least of it. Going forward, the planet’s air won’t just be warmer; it will likely also be dirtier, more oppressive,
and more sickening. Droughts have a direct impact on air quality, producing what is now known as dust exposure and in the days of the American Dust Bowl was called “dust pneumonia”; climate change will bring new dust storms to those plains states, where deaths from dust pollution are expected to more than double and hospitalizations to triple. The hotter the planet gets, the more ozone forms, and by the middle of this century Americans should suffer a 70 percent increase in days with unhealthy ozone smog, the National Center for Atmospheric Research has projected. By the 2090s, as many as 2 billion people globally will be breathing air above the WHO “safe” level. Already, more than 10,000 people die from air pollution daily. That is considerably more each day—each day—than the total number of people who have ever been affected by the meltdowns of nuclear reactors. This is not a slam-dunk argument in favor of nuclear power, of course, since the comparison isn’t so neat: there are many, many more fossil fuel chimneys disgorging their trails of black smoke than fission facilities with their finger-trap towers and clouds of white vapor. But it is a startling mark of just how all-encompassing our regime of carbon pollution really is, enclosing the planet in a toxic swaddle.
The Uninhabitable Earth Page 10