by Bryan Walsh
While presidential control of nuclear arms does keep potentially world-ending weapons in civilian hands, however, it matters quite a bit who those hands belong to. During his last, blighted days in office, when he was drinking heavily, President Richard Nixon once boasted that “I can go into my office and pick up the telephone, and in 25 minutes 70 million people will be dead.”87 He raised the possibility of using nuclear weapons during an offensive by North Vietnam in 1972 and had to be talked down by Henry Kissinger. By the time of President Reagan’s last year in office, his aides were reportedly worried enough about his declining mental state—he would die suffering from Alzheimer’s in 2004—that they discussed invoking the Twenty-Fifth Amendment, which calls for the vice president to take over in the case of the president’s incapacity.
Trump is a teetotaler, and while some experts have raised concerns that he might be suffering from early-stage dementia, he seems in better shape than Reagan was by the end. But Trump has given the world plenty of reason to worry about whether he can be trusted with the nuclear codes. He has directly threatened North Korea with a nuclear attack, welcomed a renewed nuclear arms race with Russia, and at one point in the summer of 2017 reportedly told his military that he wanted a nearly tenfold increase in America’s nuclear arsenal, returning it to a level not seen since the Cold War. His Twitter account is an electrocardiogram of his tempestuousness—and tempestuousness is not a quality we should welcome in a person who wields as much power as Trump does.88
In the fall of 2017 a congressional committee held a hearing to examine presidential authority to use nuclear weapons.89 The very fact the hearing was held—the first one on the subject in forty-one years—was notable. But so was the outcome. Witness after expert witness told the Senate Foreign Relations Committee the same thing: there is virtually nothing preventing Donald Trump, or any president, from launching a nuclear war at their whim. Congress could act to restrict the president’s power—and a pair of Democratic congressmen introduced legislation to do just that—but it’s unlikely to pass, and of course, the president would be well within his authority to veto it.
Is Donald Trump himself an existential threat to the planet? Perhaps—but if he is, it is because the architecture the United States has built in the decades since Trinity permits him to be. The entire nuclear command-and-control system is built for surprise and for speed, the speed of missiles and rockets—not the speed of rational human decision making. It’s why accidents and miscalculations around atomic weapons are so uniquely dangerous. If the leader of an atomic power has reason to think their country is under attack from nuclear missiles, they have just minutes to decide whether that attack is authentic and whether a response—a response that could mean the end of humanity—must be launched. But should that leader hesitate, a real nuclear first strike risks wiping out their country’s ability to retaliate. End of war, end of country, end of leader.
When it comes to the existential threat of nuclear weapons, it’s less the finger on the trigger than the trigger itself, as Elaine Scarry, an English professor at Harvard University and the author of Thermonuclear Monarchy, a book that sharply critiques the presidential monopoly on nuclear weapons, told me. “People are particularly concerned about Trump, but what they don’t realize is the insanity, the obscenity of the system itself,” she said. “The obscenity doesn’t depend on any unlikeable characteristics, even if you take the person you like best in the world. You just have to run the odds for how many times you have to come close before it can really happen, and then it’s over in a day.”
We can at least begin to change that system. William Perry, who is spending the final years of his life raising the alarm around nuclear weapons, wants Washington to take one finger off the nuclear trigger and end the outdated “launch-on-warning” policy for its land-based ICBMs. Originally instituted to ensure that America’s missile silos couldn’t be destroyed by a surprise Soviet attack, the policy has long outlived whatever usefulness it had. Launch on warning is why the president has only a few minutes to authenticate a possible attack and respond, which raises the risk of mistakes. The United States holds a nuclear triad—the ICBMs, but also bombers and submarines—and the other two legs would be able to retaliate even if land-based missiles and the U.S. command structure were somehow eliminated by a first strike.
There’s no time to wait. Martin Hellman, an electrical engineer and cryptologist at Stanford University, has run the odds and compares the probability of nuclear war to a game of Russian roulette. Every nuclear crisis—every point of geopolitical tension between two atomic powers, every accidental close call with nuclear weapons that could lead to an exchange—represents a pull of the trigger. Eventually, inevitably, we’ll come upon the chamber with the bullet.
In a 2009 paper, Hellman put the annual probability of a “Cuban Missile–type Crisis” producing a nuclear war at 0.2 percent to 1.0 percent.90 That seems reassuringly low, but every year that passes compounds those odds, so much so that Hellman estimated that there was a minimum 10 percent chance that a child born in 2009 would suffer an early death in a nuclear war. Other experts have come up with higher or lower estimates, but the point is that as long as nuclear weapons exist, they will remain an intolerable, existential risk. As the report from the Canberra Commission on the Elimination of Nuclear Weapons, an international panel on the future of atomic warfare, put it in 1997: “The proposition that nuclear weapons can be retained in perpetuity and never used—accidentally or by decision—defies credibility.”91
Like any child of the 1980s, there were nights when I went to sleep fearing that I would be killed in a nuclear war—or worse, that I would somehow survive one. I was thirteen when the Cold War was said to end, and with it, so did the fear. The sword that President Kennedy said was suspended above our necks had suddenly been lifted. So it enrages me to know that my son has been born into a world where that fear is very real again, where the sword is again poised to fall.
While supervolcanoes are the most dangerous natural existential risk, nuclear weapons, I believe, remain the single most significant existential risk we face right now, today, man-made or otherwise. Not asteroids, not disease, not artificial intelligence, but the old nuclear nightmare. There is no defense against them should they be used. They are weapons of war but primarily murder civilians. They have the capacity to ruin the entire planet, even end our species. And after years of hopeful progress, we now somehow find ourselves in a moment of renewed peril. “Each of us knows, at least most of the time, that we are mortal individuals, that our friends and family are mortal,” Daniel Ellsberg told me. “What we should know is that our species is mortal as well. We have achieved the capacity to exterminate ourselves. And I’ve been using my life, the best I can, to stop that. Because I think it is worth it. Civilization with all its ills is worth struggling to preserve.” And we can preserve it, for just as the ability to end this world with nuclear weapons is in our power, so is the ability to save ourselves.
CLIMATE CHANGE
What Do We Owe the Future?
From thirty thousand feet in the air, the Greenland ice sheet seems invincible, nearly 800 trillion gallons of water locked safely away in a deep freeze. But if you get closer, you can see the cracks begin to emerge, veins of the purest blue meltwater running between folds of ancient ice. They are cracks in the foundation of the world we’ve built.
I was in Greenland in the summer of 2008 as part of a tour put on by the Danish government, which was set to host a major UN climate change summit in Copenhagen the following year. Our group spent a couple of days at a scientific camp in Greenland’s white and frozen interior, where climate researchers were digging a mile and a half deep into the ice to find clues about the state of the Earth’s past climate. The ice cores mined by the scientists contained tiny bubbles of ancient air that could reveal the temperature, the concentration of greenhouse gases, and even the ambient dust from the year the layer was formed. (Similar ice cores, as we saw in chapte
r 2, helped scientists reconstruct the climatic effects of supervolcanoes like Toba.) The ice cores functioned like tree rings for global warming, and by unlocking their secrets, scientists could better understand how Greenland’s titanic ice sheets would respond to future global warming. And if you’re part of the 40 percent of the world’s population that lives within sixty miles of a coastline, there’s no more important question.1
That work was the past of climate change, however. I had come to Greenland to see its future. On one of our last days the group took a helicopter tour of Jakobshavn Glacier, Greenland’s largest, a more than thirty-five-mile-long tongue of slithering ice on the territory’s west coast. Outlet glaciers like Jakobshavn are the drainpipes of the Arctic—as the glacier flows toward the ocean it breaks apart and melts, steadily adding to sea level rise. And as global warming has accelerated, so has Jakobshavn Glacier, which now flows at more than 145 feet a day on average, nearly three times its speed during the 1990s.2 While a 2019 study found that over the last couple of years Jakobshavn had actually begun growing again, that’s due to temporary natural cooling of nearby ocean water, and may actually indicate that the glacier could be even more vulnerable to warming in the future.3
Our helicopter landed on a rocky outcrop overlooking the glacier. Days on Greenland’s ice cap at the scientific camp—and only days, as the sun shines through midnight during the high Arctic summer—had made it seem as if ice were something eternal and unchangeable. I could walk outside the tent I shared, behold white stretching out in every direction to the horizon, and know that there were thousands of feet of ice packed beneath my feet.4 But what I saw below me now was a speckled river of ice and rock and water churning toward the ocean. And then I heard the sound. The first stage was a low rumble, like the march of a far-off army coming closer. What followed was an echo of thunder that rolled and rolled, for ten, twenty, thirty seconds, before a boom, boom, boom, each low note resounding like an orchestra’s timpani drum. Then almost a sigh, a release of tension and pressure, as if the air were being let out of the Earth, followed by a still and cold silence. This was the sound of the glacier itself giving way, calving off icebergs the size of mansions to slide into the water, where they would begin to melt and add to the seas. This was the sound of climate change in motion.5
Climate change is unlike any of the other existential risks in this book. It’s neither purely natural nor solely man-made, but rather the product of an interaction between the mechanics of the planet and our own actions as an industrialized species. While the other risks are largely binary—a nuclear war or an asteroid impact either occurs or it doesn’t—climate change is already happening, gathering force with every year that humans burn fossil fuels, cut down forests, and otherwise add billions of tons of greenhouse gases to the atmosphere. While natural risks like supervolcanic eruptions are surpassingly rare and the probabilities of coming man-made risks like artificial intelligence are all but unknowable, scientists can forecast the next several decades of global warming with chilling accuracy. And what they’re learning is frightening.
The planet’s average temperature has already warmed by about 1.6 degrees since the late nineteenth century, and it is almost entirely certain that the primary cause is man-made greenhouse gas emissions.6 That warming has accelerated, and the five hottest years on record have all occurred this decade. Global sea level has risen by eight inches over the past century, a process that is also speeding up. Arctic sea ice has shrunk by a 12.8 percent per decade on average, going back to the beginning of satellite data records in 1979,7 in part because the far north is warming so quickly that in the winter of 2018 temperatures at the North Pole occasionally rose above freezing.8 One hundred fifty-seven million more people were exposed to heat wave events in 2017 compared to 1990,9 while the annual number of global weather disasters between 2007 and 2016 was 46 percent higher than during the 1990s.10 The year 2017—which saw Hurricanes Harvey and Maria devastate American territory—was the costliest year on record for extreme weather, with an estimated $320 billion in losses worldwide. The fall of 2018 was marred by devastating forest fires—fueled in part by years of climate-change-related drought and heat—that tore through California, roasting dozens of people to death in their cars and homes.11
What’s set to come will be much worse. A shocking 2018 report from the UN’s Intergovernmental Panel on Climate Change (IPCC)—the gold standard for climate science—found that if global greenhouse gas emissions continued at their current rate, the atmosphere would warm by as much as 2.7 degrees above preindustrial levels by 2040. Some 50 million people globally could be exposed to increased coastal flooding by that year, leading to refugee flows that would dwarf what we experience today.12 By 2050 nearly a third of the world’s land surface could turn to virtual desert.13 Should warming reach 3.6 degrees—which seems likely, barring a political and economic revolution—the effects would multiply.14 And until we can stop emitting carbon—and even after that for a time—climate change won’t stop, either. This is a disaster that rolls on and on.
If it sounds bad, it is. But bad is one thing—existential is an entirely different category, and despite all we know and all we’ve experienced, it’s not certain into which category climate change will fall. This is another factor that sets climate change apart from other potential existential risks—the uncertainty of its effects. The chance of a supereruption, a major asteroid impact, or even a global nuclear war may be minuscule, but we can be confident that should they occur, the results will be catastrophic, up to the point of threatening human extinction. With climate change, though, matters are reversed. The future of the climate depends largely on our actions—on how our political, economic, and scientific systems will respond in the decades to come, whether we’ll invest in zero-carbon energy technology that cuts carbon or even invent ways to suck greenhouse gases directly from the atmosphere. But it also depends on how the climate system will respond to the carbon dioxide and other greenhouse gases we’re pouring into the atmosphere. The uncertainty is in how bad things will get, whether it will be uncomfortable, catastrophic—or existential.
There is a chance that the climate system will prove less sensitive to the billions upon billions of tons of CO2 that we’re certain to pour into the atmosphere, and therefore produce less warming than expected in the decades to come. Perhaps temperatures will rise sharply, but sea ice and tropical rain forests will show resilience to the heat. It’s possible, in the way that rolling double sixes at the craps table is possible, in the way that winning at Russian roulette is possible—which doesn’t mean it’s advisable to play.
But uncertainty runs the other way. The climate system may turn out to be highly sensitive to elevated levels of CO2 and spit out even more warming than models currently project. Arctic sea ice and rain forests could prove less resilient to climate change, leading to global feedback effects that further accelerate warming. The resulting heat waves could become so intense that major swaths of the globe would become uninhabitable to human beings. The migrations and misery that would follow could destabilize what political order remains, leaving us more vulnerable to other existential risks.
Scientists long assumed that the Greenland ice sheet I visited—parts of which have survived for a few million years—would remain mostly frozen for thousands of years more, even as the climate continued to warm. Yet more recent research warns that the Greenland ice sheet, and the even larger one in Antarctica, may be approaching or even passing a tipping point, putting them on a path to total melt one day.15 That could mean sea level rise of ten feet or more over the next 50 to 150 years, enough to swamp cities like London, New York, and Shanghai by 2100.16 What I witnessed on the Jakobshavn Glacier in 2008 could have been the beginning of the end of the world—at least as we know it. Or it might have been the melting of a warm summer day.
We won’t know for sure until the future arrives. That’s another way that climate change confounds us. Unlike the conventional air pollutants that c
ause smog, which can be washed from the air in a matter of days, greenhouse gases like CO2 linger in the atmosphere for decades, even centuries. Man-made climate change has a cumulative effect that worsens as time passes. What we’re experiencing today is only a fraction of the warming that will ultimately result from the carbon we’ve emitted since the first coal-fired engines were ignited. The rest will be felt by our descendants, our poisoned legacy to them. Given how self-centered and shortsighted human beings tend to be—political leaders very much included—that delay dissipates the motivation to act on climate change now.
And there’s one final characteristic that sets climate change apart from other potential existential risks. We can fight nuclear war by pushing for disarmament. We can defend the Earth against asteroids with very large nuclear weapons. We can combat engineered pathogens by regulating genetic engineering technologies. In each case—unless we’re the ones launching nuclear missiles or releasing a deadly new virus—the existential threat is outside of us, and largely beyond our individual actions. But with climate change, virtually everything we do on earth—eat, drive, fly, work, watch television, have children—contributes to the threat, a threat built out of each of those actions, multiplied a billion, trillion times. As New Yorker writer Elizabeth Kolbert has written, when it comes to climate change, “we are the asteroid.”17
This is the conundrum of climate change as an existential risk. The economists Gernot Wagner and Martin Weitzman put it this way in their book Climate Shock: The Economic Consequences of a Hotter Planet: “There’s always a small chance that any particular final temperature wouldn’t cause any damage. There’s also the small chance that it would cost the world.”18 The challenge we face—in all existential risks but in climate change especially—is to keep that uncertainty and that responsibility from crushing us.
The early indications are not good.