3. NEW CLIMATE LAND
THE JAKOBSHAVN GLACIER on the west coast of Greenland is the fastest-moving glacier on Earth. It’s also one of the most photographed, drawing climate paparazzi from around the world. If you’ve seen images of enormous chunks of ice falling off the sapphire-blue face of a glacier in news reports or documentaries, you’ve probably seen the Jakobshavn. It’s the Kim Kardashian of glaciers—fast and unpredictable but symbolic of changes in our world in a way that makes it difficult to ignore. On my flight from Copenhagen to Kangerlussuaq, a town in southern Greenland that is the main launching point for visits to the ice sheets, I was, I admit, excited about the prospect of seeing the famous glacier up close.
My guide for the trip was Jason Box, an American climatologist who was working for the Geological Survey of Denmark and Greenland, a quasigovernmental agency that has a keen interest in understanding what is going on with the Greenland ice (Greenland, a former province of Denmark, is still a territory of the Danish kingdom). Box is a young maverick scientist and Greenland ice junkie who got a lot of attention in 2012 when he publicly predicted just weeks before the summer melt season began that Greenland would experience a record-breaking year for ice melt. And he was right. During the summer of 2012, a heat wave warmed the Arctic much more than climate models had predicted, and the Greenland ice started melting like ice cream on a summer sidewalk. Usually, only the lower elevations of Greenland melt during the summer; in 2012, melting was recorded on the entire surface of the ice sheet, including the highest elevations. Aerial photos showed rivers of luminous blue water flowing across the surface of the ice sheet, disappearing into what scientists call moulins, which are basically big holes in the ice where the rivers waterfall down to the interior of the glacier. The melt of 2012 attracted international media attention, and a YouTube video of a tractor being washed down a river swollen with meltwater in Kangerlussuaq, attracted millions of viewers.
When I met Box at the Kangerlussuaq airport, he had that scientist-in-the-wild look—scruffy, windblown hair, a big black duffel bag over his shoulder. With his goatee and gently rebellious manner, Box has the air of a skate punk made good. After chatting for a few minutes, he and I headed out into Kangerlussuaq. The town, such as it is, sprang up around the runway, which was built by the US military during World War II—and it still feels like a military base, with Quonset huts transformed into shops and hotels. I was surprised by the number of middle-aged people in town wearing new North Face jackets. “Disaster tourism,” Box explained. “They’re here to say goodbye to the ice sheets.”
We walked down the main street, where I got my first look at Greenland—the high, rolling hills reminded me, oddly, of the hills north of San Francisco. Of course, in Greenland, there are no trees—and at least in June, when I was there, there was nothing else green either. Even though it was early summer, it was still chilly enough that we needed to wear light down jackets. There was no ice in view, but Box said there were plenty of glaciers just over the horizon. “You can hike to them in a few hours,” he explained. Surprisingly, I could smell the ice in the air, as if someone had left a huge freezer door open.
We checked into what Box called the “science hotel” on the edge of town. It was basically a Quonset hut outfitted with beds and cable TV. We went for a quick evening walk, and Box showed me the Watson River where the YouTube of the tumbling tractor had been filmed during the 2012 melt. The river was about thirty feet wide now, docile as a backyard brook, gray with glacial silt. During the peak of the 2012 heat wave in Greenland, the Watson had been a raging torrent, flowing with ten times more water than the River Thames in England.
As we walked around town, Box explained that his goal on this trip was to test some unorthodox ideas about why Greenland was suddenly melting. Among other things, he believed it might be related to the darkening of snow caused by soot drifting down onto the ice sheet from coal-fired power plants in China and wildfires in the American West and northern Canada, as well as by dark-colored algae and bacteria growing on the surface of the ice. “Dark snow absorbs more heat than clean snow, which makes it melt faster,” Box explained. “How big is the impact in a place like Greenland? I don’t know. But it could be significant. And it’s one of many things that are not in the climate models right now.”
Most of the water that will drown Miami and New York and Venice and other coastal cities will come from two places: Antarctica and Greenland. Often you hear about the disappearance of the snows on Mount Kilimanjaro or the glaciers in Patagonia, but in the context of drowning cities, land-based glaciers won’t contribute much. What really matters is what happens on the two big blocks of ice at either end of the Earth.
The risks in Greenland and Antarctica, as scientists understand them, are very different. Antarctica is about seven times bigger than Greenland and contains much more ice. If the whole continent were to melt (a scenario that would likely take thousands of years), it would raise the Earth’s sea levels by about two hundred feet. If all of Greenland were to go (a scenario that could take significantly less time), it would raise sea levels about twenty-two feet. To put the volume of water we’re talking about here into perspective, if all seven billion human beings on the planet suddenly jumped into the ocean, it would raise sea levels about one hundredth of an inch. Right now, melting from Greenland contributes roughly twice as much to current sea-level rise as Antarctica—but that may change in coming decades.
The Arctic, where Greenland is located, is one of the fastest-warming places on the planet. Not surprisingly, the main issue here is melting on the surface of the ice sheets, which is driven not only by warmer air temperatures but also by the amount of moisture in the air, the speed and direction of the winds, the cloudiness of the skies, and, as Box hypothesized, how much the surface of the ice has been darkened by soot or organisms like bacteria and algae.
Antarctica, in contrast, is the coldest place on Earth. East Antarctica, where the biggest ice sheets are located, is particularly frigid. Surface melting is not an issue here. But that’s not the only way an ice sheet can disappear. In Antarctica, scientists are more concerned about warming ocean water melting glaciers from below and destabilizing the entire ice sheet. This is particularly worrisome in West Antarctica. Many of the biggest glaciers there, including Thwaites, which is roughly the size of Pennsylvania, are what scientists call marine-terminating glaciers, because large portions of them lie below sea level. Subtle changes in currents around West Antarctica have brought warmer water to the region. The change is small, but it’s enough to increase the melt rate on the underside of these glaciers. Floating ice shelves, which grow like fingernails where the glaciers meet the ocean, are particularly vulnerable to melting from below. If the waters continue to warm, they are likely to fracture and break off. The crack-up of these floating ice shelves will not in itself raise sea levels (just as ice melting in a glass doesn’t raise the level of liquid). But they play an important role in buttressing, or restraining, the glaciers behind them. If they collapse, the glaciers—some of them are ten-thousand-foot-thick mountains of ice—will be free to slide into the ocean.
Another factor that increases the risk in West Antarctica is the shape of the continent itself. If you had X-ray vision and could see though the ice, you would see that the ground below the ice sheet in West Antarctica is a reverse slope that has been depressed by the weight of the glaciers over millions of years. “Think of it as a giant soup bowl filled with ice,” Sridhar Anandakrishnan, a polar glaciologist at Penn State University, told me. In this analogy, the edge of these glaciers sits perched on the lip of the bowl, and that lip is a thousand feet or more below sea level. Behind the lip, the terrain falls away on a downward slope for hundreds of miles, all the way to the Transantarctic Mountains, which divide East and West Antarctica. At the deepest part of the basin, the ice is more than two miles thick.
Some scientists fear that if the ocean around Antarctica continues to warm and the ice shelves collapse, these big glaciers may slip off their grounding lines and begin retreating backward down the slope, like “a ball rolling downhill,” Ohio State glaciologist Ian Howat explained. The deeper down the slope the glaciers retreat, the taller and more unstable the cliffs at the calving front become, and the faster they can fracture and fall into the sea, eventually leading to what scientists call a runaway collapse of the ice sheet. And that, of course, would raise sea levels—fast.
In early 2017, a 100-mile-long crack opened in the West Antarctica ice sheet. (Photo courtesy of NASA)
The melting of Greenland and Antarctica will not be felt equally around the world. Paradoxically, the melting of Greenland will have a bigger impact in the southern latitudes; the collapse of glaciers in Antarctica will be felt more in the northern latitudes. Scientists call this regional effect fingerprinting, and it’s a consequence of the way gravity spreads the water around the Earth as it spins. In both Greenland and Antarctica, the ice sheets melt and their mass gets smaller, which reduces their gravitational pull on the water around them. This causes the sea levels in the immediate area to fall—but that falling water pushes the water higher on the opposite side of the Earth. So when Greenland melts, it has a disproportionately bigger impact on Jakarta than on New York; when Antarctica melts, it has just the opposite impact. For example, the collapse of the big glaciers in West Antarctica would cause an average global sea-level rise of about ten feet. But in New York City, thanks to the pull of gravity, the water would rise thirteen feet.
“It’s hard to get your mind around how fast the Arctic is changing,” Jennifer Francis, an atmospheric scientist at Rutgers University, told me before I left for Greenland. According to NASA, Greenland is losing three times as much ice each year as it did in the 1990s. Between 2012 and 2016 alone, a trillion tons of ice vanished—enough to make a giant ice cube that is six miles on each side (that’s taller than Mount Everest). Not so long ago, the Northwest Passage, the storied northern route from the Atlantic to the Pacific Ocean, required an icebreaker ship to navigate it. During the summer of 2016, seventeen hundred people cruised through the passage aboard the Crystal Serenity, a diesel-powered luxury ship complete with multiple swimming pools, movie theaters, and a crew of six hundred. By 2040, the summer sea ice in the Arctic is likely to vanish entirely—you’ll be able to windsurf at the North Pole.
In the past twenty years, the Arctic has warmed by more than three degrees Fahrenheit, roughly twice as fast as the global average. As the ice melts, the region’s albedo, or reflectivity, changes. Clean, fresh snow is one of the most reflective substances known in nature, reflecting away more than 90 percent of the sunlight that hits it. But as the ice softens, its structure alters, lowering the reflectivity and absorbing more heat. As it melts away, more water and more land are exposed, both of which are darker, and both of which absorb still more heat. This in turns melts more ice, creating a feedback loop that can accelerate quickly.
This dramatic change in the Arctic may be causing ripple effects throughout the Earth’s climate system. For example, some research has suggested a connection between the Arctic sea ice decline and the intensity of California’s recent record drought (although the connection is not definitive). Other research has suggested that warming in the Arctic is reducing the temperature contrast between the Arctic and the tropics, causing wind patterns in the Northern Hemisphere to slow down. The result has been more summer climate extremes, including the deadly 2003 European heat wave and severe flooding in Pakistan in 2010.
Of course, scientists have understood the basic physics of reflectivity for a long time. But the behavior of ice sheets, which is notoriously hard to capture with conventional climate models, can come very close to chaos theory—where small changes in, say, the path of the jet stream or the amount of cloud cover can lead to enormous effects. The Great Melt of 2012 was an example of this. “Scientists didn’t expect to see a total melt of Greenland for decades,” said Michael Mann, the director of the Earth System Science Center at Penn State. “When it happened, you had to wonder—what is missing from our models? Is there some basic physics that we don’t understand—or is there a human factor that we are not calculating, like the effects of soot on the snow?”
As every schoolkid knows, a water molecule is made up of two parts hydrogen and one part oxygen. Hydrogen was formed during the Big Bang roughly 14 billion years ago, while oxygen—a more complex element—was forged sometime later in the superhot interiors of stars. When stars died and went supernova, the explosion blew their elements into space, where oxygen and hydrogen mingled to form water.
The universe is awash in water. Scientists recently found a giant cloud of water surrounding a black hole 12 billion miles from Earth. In our solar system alone, the interiors of Jupiter, Saturn, Neptune, and Uranus have enormous quantities of the stuff. Mars has ice caps on its poles, just like Earth, as well as belts of glaciers in its southern and northern latitudes (in fact, scientists have calculated there’s enough water in glaciers on Mars to cover the entire surface of the planet with three feet of ice). The moons of Saturn and Jupiter have oceans beneath their icy surfaces. What makes Earth’s water unusual is that it exists in a glorious liquid state between ice and vapor, and it’s not too salty or too acidic or too alkaline. And we have a lot of it. The Earth’s oceans cover about 70 percent of the surface of our planet. Without this vast cache of water, not only would there be no sushi and no kayaking and no warm showers after a hard day’s work, but life as we know it would not exist. Life was born in the water and evolved there for billions of years before the first fish crawled up on the beach and set up camp on dry land.
What’s not very well understood is where all the water on Earth came from. The most popular explanation is that it accumulated from icy comets and asteroids that battered the planet during the first billion years or so of its existence. That’s a lot of dirty snowballs flying in from outer space, but it’s possible. Another theory is that at least some of the water hitched a ride on the grains of dust that glommed together to form the Earth 4.6 billion years ago. Wherever the source was, scientists know the amount of water on Earth has been fixed for billions of years. It just gets rearranged, depending on the temperature of the planet.
The coming and going of ice ages, an accepted part of Earth’s history for everyone except the most literal-minded creationists, wasn’t well understood until the 1940s, when a Serbian engineer named Milutin Milankovitch hypothesized that wobbles in the Earth’s orbit altered the amount of sunlight that hit the planet at regular intervals, causing just enough variation in the Earth’s temperature to trigger ice ages. As ice grew every 100,000 years or so, locking up more water, the seas fell. As the ice melted, the seas rose. If you watch a speeded-up visual rendering of the Earth over millions of years, the ice comes and goes in rhythm. It looks like the planet is alive and breathing.
The day after I arrived in Kangerlussuaq, we were supposed to fly up to Ilulissat, a small town on the coast that has become a scientific Mecca because it sits at the foot of the ice sheets. But the helicopter pilot Box had hired to get us out onto the ice—helicopters are like bicycles for Greenland ice scientists—was nowhere to be found. And without a chopper, it’s virtually impossible to get out onto the glaciers to begin fieldwork.
So Box and some of his colleagues spent the day knocking around Kangerlussuaq. Box was clearly impatient with the delay—the clock was ticking, and every hour we spent on solid ground felt like an hour wasted. But we had to eat, and that evening, Box and I walked a mile or so to a small restaurant on the edge of a meltwater lake that served traditional Greenlandic fare like musk ox steak, smoked halibut, and whale carpaccio.
Over dinner, Box and I talked about the Big Melt of 2012. The fact that the real-world melt happened so much faster than models had predicted meant that something was missing from the models. But what? Did the wavering jet stream bring a heat wave to the region? Was it the heat-trapping properties of low clouds? Perhaps. But Box, who was working on what he called a “unified theory of glaciology,” believed that soot-and-bacteria-darkened snow was a powerful overlooked factor. “It’s going to take years to put all this together,” he explained. “Unfortunately, given the rate at which the world is changing, those are years we don’t really have.”
Part of Box’s charm, I discovered, is that he is not afraid to paint in broad strokes and is very conscious that his real audience is not other scientists but the general public, who, as he sees it, have been betrayed by the hesitance of scientists to make bold predictions. For Box, this is not a problem. For instance, in 2009, he announced that the Petermann Glacier, one of the largest in Greenland, would break up that summer—a potent sign of how fast the Arctic was warming. Box even led a scientific expedition to place instruments on the remote glacier so he could better track its disintegration. Most glaciologists thought he was nuts—especially after the summer passed and nothing happened. In 2010, however, Petermann began to calve; two years later, it was shedding icebergs twice the size of Manhattan.
“I like ice because it’s nature’s thermometer,” Box told me over musk ox pizza. “It’s not political. As the world heats up, ice melts. It’s simple. It’s the kind of science that everyone can understand.”
At first, real-time monitoring of ocean levels had nothing to do with sea-level rise. It began with simple tide gauges in the early nineteenth century. In 1807, Thomas Jefferson requested that the US government begin a systematic survey of the coastline to map the new nation and facilitate maritime commerce. Because the coastline changes with the tides, that meant the surveyors also needed to begin measuring changes in the coastal water levels. (The oldest continuously recording tide gauge in the world is at the end of a pier near Chrissy Field in San Francisco; it has been recording water levels since June 30, 1854.)
At first surveyors used tide staffs, which were basically tall wooden rulers that had to be read by a person on the spot. By the late nineteenth century, the staffs gave way to rudimentary tide gauges that consisted of a pipe mounted on the end of a pier with a float in it; the float was attached to a pen that would record the ups and downs of the water on a roll of paper. Today, tide gauges are extremely high-tech, using microwaves to measure the precise distance to the surface of the water, then beaming it up to satellites, making it instantly available to researchers around the world.
No matter how accurate tide gauges are, however, the problem is that their measurements are always relative to the land they are placed on—and that land is often moving. In some spots, like the Gulf Coast of Louisiana, the ground is sinking, because of subsidence from groundwater pumping or other issues, so if you look at just the tide gauge, it looks like the sea is much higher than in other places. Sometimes, in places like Alaska or Finland, the land is actually rising, due to a phenomenon called glacial rebound.
New York City is a good example of glacial rebound in action: twenty thousand years ago, during the last ice age, the weight of the ice sheets depressed ground beneath them, mostly in Canada and the upper United States, causing the ground in what is now the New York City area to bulge out (think about how a couch cushion bulges when you put your hand on it). That bulge under New York is now subsiding, causing land to sink, which increases the local rate of sea-level rise.
The solution to all these local variations, of course, was to average tide gauges around the world. Still, tide gauges could only offer a rough approximation of something as complex as global sea levels. New technology provided a better way. In 1992, NASA and CNES (the French space agency) launched TOPEX/Poseidon, the first satellite capable of precisely measuring sea-level change. Three more have been deployed in succession since then, each overlapping with the previous one to provide an uninterrupted twenty-five-year record of sea-level change. The most recent satellite is the Jason-3, which launched in early 2016. The Jason-3 circles the Earth continuously, bouncing radar waves off the surface of the sea to measure the distance between the satellite and the water, as well as the height of the satellite relative to the center of the Earth. These measurements, from which the influence of the tides and the waves is removed, are free from distortion by rising or sinking land. When this data is combined with tide gauge averages, as well as measurements from ocean floats that record changes in the heat content of the ocean, it gives scientists a very good picture of how much the sea level is rising and what the causes are.
With better data, scientists are now able to more clearly understand other factors beyond land movement that lead to variations in the rate of sea-level rise. One is the gravitational fingerprinting I mentioned earlier, which pushes water into the Southern Hemisphere from melting ice sheets in Greenland and into the Northern Hemisphere from Antarctica. Another important factor is temperature, which fluctuates daily, seasonally, and annually. As water heats up, it expands (eventually it boils and turns to vapor, of course—not something we have to worry about with the world’s oceans anytime soon). Globally, the thermal expansion of the oceans caused by the Earth’s rising temperature has contributed about half of the observed sea-level rise in the last fifty years. In the future, that percentage will decline as thermal expansion is dwarfed by increasing melt rates in Greenland and Antarctica.
Ocean currents also impact regional sea levels. On the East Coast of the United States, the speed of the Gulf Stream—the underwater current that carries cold water from the north down to the equator, then loops around and carries warm water back up to the Arctic—can influence sea levels all the way from Virginia to Florida. A faster Gulf Stream pulls water away from the coast; as it slows down, it walls up, raising sea levels. Norfolk, Virginia, which is a sea-level-rise hotspot due to its low-lying topography and ground subsidence, has not been helped by the fact that a slowing Gulf Stream is pushing more water against the coast. One recent study, between 1950 and 2009, showed that the seas north of Cape Hatteras rose three to four times faster than the global average.
The most surreal consequence of melting ice and rising seas is that together they are a kind of time machine, so real that they are altering the length of our days. It works like this: As the glaciers melt and the seas rise, gravity forces more water toward the equator. This changes the shape of the Earth ever so slightly, making it fatter around the middle, which in turns slows the rotation of the planet similarly to the way a ballet dancer slows her spin by spreading out her arms. The slowdown isn’t much, just a few thousandths of a second each year, but like the barely noticeable jump of rising seas every year, it adds up. When dinosaurs roamed the Earth, a day lasted only about twenty-three hours.
Jason Box was born in Colorado and spent his early years in suburban Denver, where his father worked as an electrical engineer for an aerospace company. “Jason was smart, and he liked to cause trouble,” recalls Box’s older sister Leslie. When Box was about ten, he erected a lightning rod in a field and nearly burned the town down.
Jason Box coring ice in Greenland. (Photo courtesy of Peter Sinclair)
As a teenager, Box often wore a sleeveless military jacket and blasted around on a skateboard listening to bands like the Dead Kennedys, Bad Religion, and Judas Priest. He enrolled at the University of Colorado Boulder, where he and his sister played in a garage band called the Sensors (Box played guitar and sang). During gigs, Box liked to decorate the stage with old electronic equipment like oscilloscopes and broken fax machines. “Jason was one of those guys who could drink hard and party at night and then get up early in the morning and go to an intense science class,” his sister recalled. At Boulder, he bounced from computer science (“too nerdy”) to astronomy (“amazing but not down-to-earth”) to geology (“too slow”). “Then I took a climatology course and saw the Keeling curve and that did it,” Box told me. The Keeling Curve, named after scientist Charles David Keeling, is the famous graph that measures the rise of carbon dioxide concentrations in the air since 1958, which is the bedrock of global warming science. “I knew the implications were huge,” said Box.
Box took his first trip to Greenland when he was twenty years old. “I remember him walking into my office and saying, ‘I want to go to Greenland with you,’” said Konrad Steffen, a top glaciologist who at that time was a professor of geology at the University of Colorado. Box worked to install and maintain mini–weather stations around Greenland and became increasingly interested in how wind, temperature, and sunlight affect glaciers. After writing a PhD thesis on how much Greenland glacier ice is lost from evaporation, Box took a position at Ohio State University, home of the prestigious Byrd Polar and Climate Research Center. In 2013, Box, his wife, Klara, and his young daughter, Astrid, moved to Copenhagen and joined the Geological Survey of Denmark and Greenland. One of Box’s first tasks was to perfect a computer model that monitors Greenland’s mass ice change in real time; he was also involved in helping the Danish government review projects in Greenland that might exploit the melting ice, such as new hydroelectric dams.
In the summer of 2012, Box was at New York’s LaGuardia Airport on his way to Greenland when he saw the first video images of the massive wildfires in Colorado. “It’s a strange feeling, watching your home state burn on TV,” Box told me. But it gave him an idea. NASA’s Thomas Painter recalled, “Jason called me and said, ‘Do you think soot from wildfires might be melting Greenland?’ I told him that I didn’t know if soot particles were landing there, but it was certainly conceivable, given the circulatory patterns of the Earth’s atmosphere.” A few weeks later, the case for this grew stronger when Box was scanning laser satellite images of Greenland and discovered a cloud of smoke—possibly drifting soot from a wildfire—over the ice.
The idea that soot can have a powerful effect on the melt rate of snow and ice is not new. NASA scientist James Hansen explored the idea in a paper published in 2004, arguing that if soot reduced the reflectivity of Arctic ice by just 2 percent, it had the same effect on the melt rate of the glacier as a doubling of CO2 concentrations in the atmosphere. What was new was Box’s attempt to link the Colorado wildfires directly with the 2012 meltdown in Greenland—to make a direct connection between a particular fire and a particular melting event.
A lot of scientific ideas are poetic, but this one really underscores the way small changes in the climate can amplify each other in unpredictable ways. As Box sees it, warmer temperatures in the United States stress pine trees in the Rockies, leaving them vulnerable to pine bark beetles, which bore into the trunks of the heat-weakened trees, killing them and turning them into tinder. A backpacker’s campfire throws out a spark, a tree ignites, and soon the mountainside is burning and the soot is drifting up, some of it lofted into the jet stream and settling in Greenland, darkening the snow and accelerating the transformation of ice into water, which runs down into the North Atlantic, and, eventually, pushes a little deeper into Miami, Shanghai, New York City, Venice, Mumbai, Lagos, and the rice fields of Bangladesh, and then a little deeper still.
Eugene Domack, a geologist at the University of South Florida, was one of the last human beings to see the Larsen B ice shelf on the Antarctic Peninsula. In December 2002, in the middle of the polar summer, he spent three weeks in Antarctica sampling mud from the bottom of the Amundsen Sea—he was looking for rocks that had been rafted out to sea on the bottom of icebergs, which would tell him something about how fast the ice sheets had broken up in the past. That December, he spent a lot of time in the waters just in front of the face of Larsen B. At the time, the Larsen B was one of the biggest ice shelves in the world—roughly the size of Rhode Island, and up to two hundred feet thick. That summer, Domack noticed it was particularly warm, and if he could have gotten up onto the top of the ice shelf, he would have seen melt ponds everywhere (the Antarctic Peninsula, which juts north off the continent, is the only part of Antarctica that has shown significant surface warming in recent decades). But Domack, who never got up on top of the ice, had no sense that the ice shelf was unstable. It had, after all, been there for twelve thousand years.
A month or so after he got back to the United States, he was astonished when Larsen B made international news: the entire ice shelf had collapsed in spectacular fashion. Its demise was chronicled by satellite images. The crack-up took less than a month. “It was mind-blowing,” Domack told me. “No one thought it could disintegrate that fast.”
For climate scientists, both the collapse of Larsen B and the full melt of the surface of Greenland’s ice sheet a decade later were big wake-up calls. “It showed us how much we didn’t understand about what is going on with the ice sheets,” said Peter Clark, a leading sea-level rise expert at Oregon State University. Clark was one of the lead authors on the sea-level rise section of the fifth (and most recent) report by the Intergovernmental Panel on Climate Change, which was published in 2013—too soon for studies that explored the big melt in Greenland the year before to be included, as well as more recent studies that highlighted the fragility of West Antarctic glaciers. As a result, as soon as it was published, the 2013 IPCC report was already out of date.
This matters a lot, because the IPCC reports are important documents, providing the scientific basis for global climate agreements and coastal planning around the world. The 2013 IPCC report, which projected a high end of possible sea-level rise of about 3 feet 2 inches, was particularly important, because it was the scientific basis for the 2015 climate treaty negotiations in Paris, which were viewed by many politicians and activists as the last good shot to get a meaningful global agreement to reduce carbon pollution. The IPCC report, which gets updated about every six years, is a synthesis of both historical data (how fast and how high sea level has risen in the past) and state-of-the-art modeling and research. Of course, science moves slowly and deliberately, and the IPCC report does not sell itself as cutting-edge knowledge. Still, because the IPCC report is viewed as the gold standard by politicians and scientists, many people think the IPCC’s 3-foot-2-inch high-end estimate for sea-level rise by 2100 is as bad as it can get. It’s not.
After 2012, with the combination of the big melt in Greenland and the collapse of Larsen B, it was pretty obvious that the ice sheets were changing far faster than forecast. How much did scientists really understand now about what might happen in the future? NASA’s James Hansen published a paper in 2015 stating that, due to the exponential increase in ice sheet melting in Antarctica, we could see as much as nine feet of sea-level rise by 2100. Another paper by Rob DeConto at the University of Massachusetts and David Pollard at Pennsylvania State University suggested that the rapid calving and retreat of big glaciers like Thwaites and Pine Island in West Antarctica could alone contribute over three feet of sea-level rise by 2100. And what scientists in the field were seeing with the breakup of ice shelves and the speeded-up melting of glaciers confirmed this. “The latest field data out of West Antarctica is kind of an OMG thing,” Margaret Davidson, head of coastal planning for the National Oceanic and Atmospheric Association, said in a 2016 email.
For anyone living in Miami Beach or South Brooklyn or Boston’s Back Bay or any other low-lying coastal neighborhood, the difference between three feet of sea level rise by 2100 and six feet is the difference between a wet but livable city and a submerged city—billions of dollars’ worth of coastal real estate, not to mention the lives of the 145 million people who live fewer than three feet above sea level, many of them in poor nations like Bangladesh or Indonesia. The difference between three feet and six feet is the difference between a manageable coastal crisis and a decades-long refugee disaster. For many Pacific island nations, it is the difference between survival and extinction.
The big question remained: What were the key drivers of rapid ice melt that scientists didn’t understand or incorporate into their models? Was it a wobbling jet stream? Changing ocean currents? Soot on snow? In their paper on West Antarctica, DeConto and Pollard had gotten much faster collapse of the glaciers simply by factoring in the effect of a small amount of meltwater on the surface of the West Antarctic glaciers, as well as a better understanding of the physics of ice-cliff fracturing. “We just don’t know what the upper boundary is for how fast this can happen,” Richard Alley, a geologist at Penn State University who probably understands ice sheet dynamics better than anyone, told me. “We are dealing with an event that no human has ever witnessed before. We have no analogue for this.”
Box, like most scientists I’ve talked to, readily acknowledged that the IPCC estimate of 3 feet 2 inches of sea-level rise by 2100 is far too low. I asked him if he thought 6 feet by 2100 was still too low.
Box replied without hesitation: “Shit yeah.”
Finally, dinners consumed and nervous feet nearly tapped out, Box was able to find the helicopter pilot and we were ready to go. We hopped on a short flight to Ilulissat, which was about a hundred miles up the western coast of Greenland. As soon as we got into the air, I could see the ice sheets—they looked like big white rivers flowing down to the dark blue sea. As we neared Ilulissat, Box pointed out the Jakobshavn to me—we went right over it. You could see the wide, flat catchment area of the glacier, and the river of ice that fed down toward Disko Bay, abruptly stopping at the water’s edge. Icebergs were scattered in the fjord in front of it. From the air, they looked like pebbles.
We landed at the small airport at Ilulissat, unloaded our gear, and took a shuttle bus to our hotel. Ilulissat (Greenlandic for “icebergs”) was charming, a fishing village with brightly colored New England–style wooden houses sloping down to an ocean cove. The Hotel Arctic, where we were staying, was perched on the hillside above the cove with views out toward the fjord. It felt like the Waldorf compared to the hut we’d stayed at in Kangerlussuaq (“This is where Al Gore stays when he visits,” I heard a guest at the Hotel Arctic say as we were checking in). While Box double-checked his gear, I went for a short walk along the bluff near the hotel. Icebergs drifted not far offshore, glinting in the afternoon light. Some were as big as the New York Public Library on Fifth Avenue, others as small as a mailbox. They reminded me of a battalion of soldiers heading into battle.
In the morning, we took a shuttle to the airport, where we met Malik Nielsen, our next helicopter pilot. He was by turns edgy and relaxed, a man who knew what he was doing but never forgot the thrill and danger of it. We discussed the flight plan, which was to fly out and have a look at the calving front of the Jakobshavn, then go up onto the ice field to collect soot samples from the surface of the ice sheet.
Icebergs in Disko Bay, Greenland. (Photo courtesy of the author)
We climbed into our Bell 212 helicopter, a common workhorse in Greenland, which was surprisingly spacious inside. Peter Sinclair, a filmmaker who joined us for the trip, sat up front with the pilot; Box and I were in back. We slipped on our headsets, double-checked everything, and were off for the twenty-five-minute flight to Jakobshavn.
We flew right along the bay in front of the glacier at an altitude of about 500 feet. It was like flying over an iceberg spawning ground. The face of the Jakobshavn loomed ahead of us, a blue-white wall of ice. I watched chunks of ice calving off, falling into the sea.
Before we got to the face, the chopper turned south and flew toward the rough mountains alongside the glacier. We were looking for a patch of open ground that Box had identified in satellite photos. Box and the pilot exchanged a few words on the intercom; then Box smiled and gave me a thumbs-up. A few moments later, the chopper touched down on an unremarkable bit of rocky tundra about the size of a football field, and Box jumped out. “Welcome to New Climate Land,” he said, then launched into a giddy, erudite stand-up monologue for Sinclair’s camera that would have made his high school science teacher proud. For thousands of years, he explained, this spot had been covered by a tall building’s worth of ice and snow. But now, in just the last few months, the last traces of that ice and snow had disappeared. “We are likely to be the first human beings to ever stand on this piece of ground,” Box said excitedly.
Before we took off for the interior of the ice sheet, I asked if we could take another pass along the front of the Jakobshavn. Box nodded but warned that we couldn’t get too close. Big calving events are unpredictable and can create dangerous air turbulence as massive ice cliffs collapse into the fjord.
Apparently Nielsen wasn’t too worried about this, because as we approached the calving front of the glacier, he flew so close that I felt like I could reach out and touch it. A wall of ice streamed by the chopper window—blue, translucent, cracked. Just ahead of us, I watched a huge chunk collapse into the water. It fell straight down, like a trapdoor had opened beneath it. I looked again, and another smaller piece fell. I could feel the physics at work here, the ancient and unstoppable force of a glacier sliding down into the sea and reshaping our world.