Ice Melt, Harbinger Of Accelerated Melting

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When water accumulates on the surface of an ice sheet, more sunlight gets absorbed, which results in more melt, in a cycle that builds on itself. This year’s melt season began so early that many scientists couldn’t believe the data they were seeing. PHOTOGRAPH BY DANIEL BELTRÁ

Elizabeth Kolbert has appeared in these pages about as frequently as any other individual we admire (McKibben, an activist and a writer, wins the race with a few more posts pointing his way), or any other topic (take your pick between libraries, entrepreneurial conservation or a few others that nudge past EK in the same race) we care deeply about. She is an activist through her writing, advocating on behalf of our better understanding of the challenges facing the next generations. Epochal challenges that we have some ability to influence the outcome of. So, when she delivers biblical proportions of reporting, we read every word and pass it on:

GREENLAND IS MELTING

The shrinking of the country’s ice sheet is triggering feedback loops that accelerate the global crisis. The floodgates may already be open.

Not long ago, I attended a memorial service on top of the Greenland ice sheet for a man I did not know. The service was an intimate affair, with only four people present. I worried that I might be regarded as an interloper and thought about stepping away. But I was clipped onto a rope, and, in any case, I wanted to be there.

The service was for a nasa scientist named Alberto Behar. Behar, who worked at the Jet Propulsion Laboratory, in Pasadena, might be described as a twenty-first-century explorer. He didn’t go to uncharted places; he sent probes to them. Some of the machines he built went all the way to Mars; they are orbiting the planet today or trundling across its surface on the Curiosity rover. Other Behar designs were deployed on Earth, at the poles. In Antarctica, Behar devised a special video camera to capture the first images ever taken inside an ice stream. In Greenland, he once sent a flock of rubber ducks hurtling down a mile-long ice shaft known as a moulin. Each duck bore a label, offering, in Greenlandic, English, and Danish, a reward for its return. At least two made it through.

When Behar died, in January, 2015—he crashed his single-engine plane onto the streets of Los Angeles—he was at work on another probe. This one, dubbed a drifter, looked like a toolbox wearing a life preserver. It was intended to measure the flow of meltwater streams. These so-called supraglacial rivers are difficult to approach, since their banks are made of ice. They are often lined with cracks, and usually they end by plunging down an ice shaft. The drifter would float along, like a duck, collecting and transmitting data, so that, by the time it reached a moulin and was sucked in, it would have served its purpose.

Behar was collaborating on the drifter project with a team of geographers at U.C.L.A. After his death, the team carried on with the project, which itself became a kind of memorial. When the geographers picked a supraglacial river to toss the drifters into, they called it the Rio Behar.

I flew up to the Rio Behar in July with several U.C.L.A. graduate students and two drifters. My first glimpse of it was out the helicopter window. Its waters were an impossible shade, a color reserved, in other circumstances, only for Popsicles. That fantastic blue was set against a pure and hardly less fantastic whiteness. “Greenland!” the artist Rockwell Kent wrote, after being shipwrecked in an ice fjord. “Oh God, how beautiful the world can be!”

An earlier wave of students had already set up a camp. This consisted of one orange cook tent and nine smaller tents, also orange. Beneath the camp, the ice extended more than half a mile. Dotting its surface were perfectly round holes, each an inch or two in diameter and about a foot deep. The holes were filled with meltwater. On this half-solid, half-liquid substrate, staking the tents had proved impossible. The one I was assigned was tied to a quartet of fuel cannisters. “Don’t smoke,” someone advised me.

A line of yellow caution tape had been strung about fifty yards from the Behar’s edge. Anyone venturing beyond that line, I was instructed, had to be tethered. I borrowed a mountaineering harness, clipped in, and made my way to the bank, where the team’s leader, Larry Smith, was conferring with a pair of graduate students. By ice-sheet standards, it was a balmy day—around thirty-two degrees—and Smith was wearing canvas work pants; two plaid shirts, one on top of the other; and a red fleece cap that said “Air Greenland.”

“Do you hear that?” he asked me. Above the rush of the river, there was a roaring sound, like waves crashing against a distant cliff. “That’s the moulin.”

Eighteen months after the plane crash, Smith still had trouble talking about Behar. He had brought to the river a half-litre bottle of Coke, which he was carrying in a side pocket of his pants. In the field, he told me, Behar had more or less lived on Diet Coke. He apologized for having to substitute the sugared variety.

Smith twisted open the bottle, drank from it, then handed it around. Each of the students took a few swigs. When Smith got it back, he wrote his e-mail address on the label, with the message, “If found, please contact.” Then he lofted the bottle into the Behar and we all watched it disappear, floating toward the moulin in the icy blue.

People attracted to the Greenland ice sheet tend to be the type to sail up fjords or to fly single-engine planes, which is to say they enjoy danger. I am not that type of person, and yet I keep finding myself drawn back to the ice—to its beauty, to its otherworldliness, to its sheer, ungodly significance.

The ice sheet is a holdover from the last ice age, when mile-high glaciers extended not just across Greenland but over vast stretches of the Northern Hemisphere. In most places—Canada, New England, the upper Midwest, Scandinavia—the ice melted away about ten thousand years ago. In Greenland it has—so far, at least—persisted. At the top of the sheet there’s airy snow, known as firn, that fell last year and the year before and the year before that. Buried beneath is snow that fell when Washington crossed the Delaware and, beneath that, snow from when Hannibal crossed the Alps. The deepest layers, which were laid down long before recorded history, are under enormous pressure, and the firn is compressed into ice. At the very bottom there’s snow that fell before the beginning of the last ice age, a hundred and fifteen thousand years ago.

The ice sheet is so big—at its center, it’s two miles high—that it creates its own weather. Its mass is so great that it deforms the earth, pushing the bedrock several thousand feet into the mantle. Its gravitational tug affects the distribution of the oceans.

In recent years, as global temperatures have risen, the ice sheet has awoken from its postglacial slumber. Melt streams like the Rio Behar have always formed on the ice; they now appear at higher and higher elevations, earlier and earlier in the spring. This year’s melt season began so freakishly early, in April, that when the data started to come in, many scientists couldn’t believe it. “I had to go check my instruments,” one told me. In 2012, melt was recorded at the very top of the ice sheet. The pace of change has surprised even the modellers. Just in the past four years, more than a trillion tons of ice have been lost. This is four hundred million Olympic swimming pools’ worth of water, or enough to fill a single pool the size of New York State to a depth of twenty-three feet.

An ice cube left on a picnic table will melt in an orderly, predictable fashion. With a glacier the size of Greenland’s, the process is a good deal more complicated. There are all sorts of feedback loops, and these loops may, in turn, spin off loops and sub-loops. For instance, when water accumulates on the surface of an ice sheet, the reflectivity changes. More sunlight gets absorbed, which results in more melt, which leads to still more absorption, in a cycle that builds on itself. Marco Tedesco, a research professor at Columbia’s Lamont-Doherty Earth Observatory, calls this “melting cannibalism.” As moulins form at higher elevations, more water is carried from the surface of the ice to the bedrock beneath. This lubricates the base, which, in turn, speeds the movement of ice toward the ocean. At a certain point, these feedback loops become self-sustaining. It is possible that that point has already been reached.

According to the “Encyclopedia of Snow, Ice and Glaciers,” glacial ice “behaves as a non-linear visco-plastic material.” To put this differently, ice, like water, flows. For reasons that are not entirely understood, ice flows faster in some parts of the ice sheet than in others. Regions where the flow is particularly swift are known as ice streams.

The East Greenland Ice-Core Project, EGRIP (pronounced ee-grip) for short, sits atop one of the longest and widest of these streams, the Northeast Greenland Ice Stream, or negis (pronounced nay-gis). This past June, I flew up to egrip on a ski-equipped C-130 Hercules, which those in the know call a Herc. The Herc had small rockets—Jet Assisted Takeoff units, or jatos—mounted below each wing. The jatos were there in case it got too hot and the runway at egrip, which consists entirely of snow, grew sticky.

EGRIP is run by a Danish glaciologist named Dorthe Dahl-Jensen. Dahl-Jensen is a soft-spoken woman with bright blue eyes and an asymmetrical sweep of white hair. She’s fifty-eight and has been working on the ice sheet almost every summer for the past thirty-five years. Initially, as a graduate student at the University of Copenhagen, she’d had to talk her professor, a geophysicist named Willi Dansgaard, into allowing her to come. Dansgaard was against the idea, because the last time he’d brought along a female student the camp’s cook had fallen in love with her and stopped cooking. As it happened, on her first trip to the ice sheet, Dahl-Jensen fell in love. She and her husband, J. P. Steffensen, also a glaciologist, have four children. During the summer, they trade off raising the kids and overseeing operations on the ice.

EGRIP is very much a work in progress. Last year’s field season was devoted to hauling equipment from a defunct ice station two hundred and seventy-five miles away. This included a whole building, containing a kitchen, a rec room, a bathroom, a dining hall, and an office. The building, which weighs thirty-five tons, was mounted on skis and dragged behind a tractor equipped with extra-heavy-duty treads.

When I arrived, midway into the 2016 field season, construction at EGRIP was still under way. A network of vaulted tunnels had been created, with floors and walls carved out of snow. These glittered from all angles, like something out of “A Thousand and One Nights.” At the bottom of one tunnel a deep pit had been cut using a chain saw, and, next to the pit, a carpenter was erecting a wooden platform. The bricks of ice that had been pulled from the pit had been lugged up to the surface and arranged into what I can only believe is the world’s northernmost outdoor bar.

All of this—the tunnels, the pit, the platform—had been fashioned to accommodate an enormous drill, parts of which had travelled with me to egrip on the Herc. The point of the project is to send the drill from the top of the ice sheet to the bottom, a distance of more than eight thousand feet. Owing to the way the ice sheet was created, layer upon layer, the drill, as it descends, will, in effect, be boring through history. (In the case of an ice stream, it is possible to step in more or less the same river not just twice but any number of times.) If all goes as planned, Dahl-Jensen told me, the drilling will be completed in 2020. Meanwhile, the ice stream will be moving at the surface, at a rate of around six inches a day, and egrip will be moving with it, meaning that the borehole will start to bend. One of the toughest challenges of the project is figuring out how to keep the drill from getting stuck.

The main building at EGRIP—the one that got schlepped across the ice—is a sort of double geodesic dome, with one dome resting on the other, like the lid on a casserole. At the very top of it there’s a cupola. The domes and the cupola are covered in rubber sheeting, and to my eye the whole arrangement resembled a big black time bomb.

My second day at egrip, everyone gathered in the double dome for what was billed as the “first ever” master’s thesis defense on the ice. The chairs in what normally served as the rec room had been rearranged, classroom style, and one of Dahl-Jensen’s students, a bearded young man named Kristian Høier, rose to discuss the issue of “surface buckling.” Although Høier spoke in English, I couldn’t understand most of his presentation, which turned on details of the equations he’d used in his mathematical model. He seemed nervous and kept sighing loudly, which I also couldn’t understand, as it was obvious that the first-ever thesis defense on the ice was going to result in the first-ever pass. When his presentation was over, Dahl-Jensen opened a case of champagne and everyone put on parkas and heavy boots to stand around the outdoor bar. It was evening, but, since the sun never sets in northeastern Greenland in June, still bright. The snow, flat and unbroken in all directions, had acquired a bluish tint. Dahl-Jensen offered a toast to Høier, who seemed intent on getting hammered as quickly as possible. I left my cup on the bar and went back into the building to get my camera. By the time I returned, my drink was halfway to a champagne slushie.

As its name suggests, the negis flows in a northeasterly direction. It has its head, as it were, at the center of Greenland, near the highest point on the ice sheet. Its mouth empties into the Fram Strait. There icebergs the size of city blocks split off, or, as geologists say, calve, and float away. Given enough time, egrip, like some drifting barge, will also reach the Fram and topple in.

All over Greenland, ice streams like the negis are picking up their pace. In the process, they are dumping more and more ice directly into the oceans. Currently, it’s estimated that Greenland is losing about as much ice from calving as it is from melt. One group of scientists argues that, of the two forms of loss, melt is the more worrisome, as, in a warming world, it must increase. But the behavior of ice streams is less well understood, and some scientists argue that, for this very reason, increased calving is potentially even more of a threat.

“The fastest way to get rid of an ice sheet is to throw it into the ocean” is how Sune Olander Rasmussen, the field-office manager for egrip, put it to me.

“The ice streams have really, really surprised us,” Dahl-Jensen said. “To drill down into an ice stream and see: How does it actually flow? How much is it sliding? How much is it melting at the bottom? I see that as the most important goal of this project.”

Once an ice stream starts to accelerate, it may be impossible to stop. “In some cases, you have, in theory, this irreversible process,” Kerim Nisancioglu, a climate scientist from the University of Bergen who works at egrip, told me. “And you set it off and it just goes. It drains.”

greenland-map-v9a

There are few roads—the ice sheet covers about eighty per cent of the island.MAP BY LA TIGRE

“This system is huge,” Nisancioglu continued, referring to the ice stream we were standing on. “It has a lot of water to drain. So it could keep going for a long time. How far can it go? Will it keep accelerating indefinitely until it runs out of ice? This is unknown.” All on its own, the negis has the potential to raise global sea levels by three feet.

The first attempt to drill through the Greenland ice sheet was made in the early nineteen-sixties at a United States Army outpost called Camp Century. Some fifty years later, the camp remains far and away the biggest thing ever built on—or, really, under—the Greenland ice. Camp Century had a bar, a chapel, a barbershop, a movie theatre, and a nuclear reactor. All were housed in a network of snow tunnels like those at egrip, but extending for miles. The ostensible purpose of the base was to promote Arctic science, but in the nineteen-nineties an investigation by the Danish government revealed this to be a ruse. What the Army had really been up to was developing a new system for storing intercontinental ballistic missiles. Its plan was to install a subglacial railway and shuttle ICBMs around in a Cold War shell game. The code name for the scheme was Project Iceworm.

The drilling at Camp Century was not exactly a secret; still, visitors were not allowed to watch while it was under way. It yielded hundreds of cylinders of ice, each about a yard and a half long and four inches in diameter. These sat around in a freezer in New Hampshire until Willi Dansgaard, Dahl-Jensen’s teacher, got hold of them.

Dansgaard, who died in 2011, was an expert on the chemistry of precipitation. Presented with a sample of rainwater, he could, based on its isotopic composition, determine the temperature at which the precipitation had formed. This method, he realized, could also be applied to snow. Dansgaard was able to read the Camp Century core as a sort of almanac of Greenlandic weather. He could tell how the temperature had changed ice layer by ice layer, which is to say year by year.

Mostly, Dansgaard’s results confirmed what was already known about climate history. For instance, he observed that Greenland had experienced a cold snap from around the year 1300 to 1800—the so-called Little Ice Age. He found that for most of the past ten thousand years it had been relatively warm on Greenland, and for tens of thousands of years before that it had been frigid…

Read the whole article here.

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