
What Greenland's Ancient Past Reveals about Its Fragile Future
Inside a tent fastened to the surface of Greenland's ice sheet, the members of the GreenDrill expedition huddled around a drilling rig. The machine whined and shook as it spun. For days the drillers had been inching through ancient, solid ice to reach the rock below.
Outside, the sun burned down through a cloudless sky. The wind, having tumbled down 4,000 feet of elevation from the domed summit of the ice sheet hundreds of miles to the west, charged over the surface in wavelike pulses. The tent shuddered like some mad bouncy house at the end of the world. The nine members of the expedition—ice and rock engineers, scientists, polar-survival specialists—knew they should be close to bedrock. But Forest Harmon, the driller working the handwheel, said he still couldn't feel the core break—the moment when the metal catcher inside the drill head separates the bedrock core from its earthly tomb.
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The GreenDrill site sat on the frozen edge of the Northeast Greenland Ice Stream, or NEGIS, a massive, moving tongue of ice that drains 12 to 16 percent of the ice sheet into the ocean. Upended and laid atop the contiguous U.S., it would look like a flowing mountain range more than a mile and half tall at its highest point and 20 to 30 miles across, extending from Boston to Washington, D.C. If the entire Greenland ice sheet melted, global sea levels would rise by about 24 feet. The NEGIS is how a good deal of that planet-altering flood would enter the sea.
The sheet won't melt all at once, of course, but scientists are increasingly concerned by signs of accelerating ice-sheet retreat. A recent report showed that it has been losing mass every year for the past 27 years. Another study found that nearly every Greenlandic glacier has thinned or retreated in the past few decades. The NEGIS itself has extensively sped up and thinned over the past decade.
Elliot Moravec, the mechanical engineer monitoring the drill-fluid pressure gauge, smiled, but only slightly. It seemed like something was about to go right, finally—in an expedition where almost nothing had before the team made it to the ice. So much in the weeks leading up to this moment had been uncertain. There were logistical delays and failed landings by military cargo planes. A more ambitious plan, which included a much larger drill and two different sample sites, had been scrapped. The project's two principal investigators were both forced to forfeit the field season at the last minute. One of them had come all the way to Greenland only to have to turn around. The other made the painful decision to not even try to make it to the ice. The rest of the team was marooned for weeks in Kangerlussuaq, a staging location on Greenland's southwestern coast, about 850 miles from the drill site. Then it had taken more than 10 flights over seven days to get them and tens of thousands of pounds of gear onto the ice.
But at this moment, with just two weeks remaining in the expedition, their bit sat at the edge of discovery. The zone below was thought to hold within it a revelation: frozen in stone was a picture of this place but ice-free. Knowing the last time this area was actually green would help scientists answer a question of enormous consequence: Is the Greenland ice sheet even more fragile than we know?
Since President Donald Trump announced his administration's desire to 'get' the world's largest island, Greenland has been the subject of sudden global attention. Climate change is exposing land formerly covered by ice, heightening political tensions on the island nation—and in the waters surrounding it as sea ice also disappears. But although the administration's plan to extract Greenland's natural resources is new, the American desire to occupy it, and pull value from underneath its frozen heart, is not.
In 1956 and 1957 the U.S. Army Corps of Engineers Snow, Ice and Permafrost Research Establishment, or SIPRE, recovered the first long ice cores from Greenland. Europeans and Americans alike had been trying to cross and dig into the ice sheet for decades before then. The ' father of continental drift ' himself, Alfred Wegener, is still entombed there. Wegener made four expeditions to study Greenland's ice in his lifetime. During his final expedition, in 1930, he died out on the ice. Just before he became a part of the ice record, he wrote: 'We are approaching a new era of polar exploration characterized by the successful utilization of new technologies in a rational manner. Everything that we want to and can measure must be measured on the ground.'
In 1956 American scientists were doing exactly that, but the reason they were there at all had as much to do with the cold war as it did with the cold ice. The government's real mission was to build Arctic capabilities so it could both operate and listen from somewhere much closer to the Soviet Union. The location where SIPRE pulled those first deep ice cores from was called Site 2, and despite its public science mission, it was also a top-secret radar installation watching 24-7 for Soviet threats. But the tense geopolitics allowed a scientific discovery that, until then, had seemed impossible: the recovery of deep ice cores that kicked off an international race to recover and interrogate deeper and deeper ice. Those ice cores, and all that would be collected after them, became a kind of high-resolution climatological bedrock on which much of our understanding of rapid climate change rests.
Although it is difficult to count the number of ice cores in existence, adding up the length of ice in just the freezers owned by Denmark (Greenland is an autonomous territory of the Kingdom of Denmark) and the U.S. gives you more than 21 miles of ancient ice. Researchers have dated them, measured the pressure of their enclosed air bubbles, characterized the structure of their snow, detected ancient volcanic cataclysms in their particulate content, and more. The results have given us an indirect way to track the timing of large and abrupt shifts in climate as far back as 123,000 years ago in the case of Greenland and 1.2 million years ago for ice extracted from Antarctica. 'They are basically a backbone of climate science in terms of giving us these continuous, high-resolution climate records,' says Joerg Schaefer, GreenDrill's co-principal investigator.
I have a personal 25-year history with one of these backbones. As an undergraduate researcher, I lived for a month on an oceanographic research vessel off Baja California. The mission was to collect sediment cores from the ocean floor. I spent hours and hours taking measurements—more than 30,000 of them—with my face pressed close to stinking, methane-rich mud.
Like ice cores, the sediment cores had visible horizontal bands. Ice cores' bands come from seasonal variations in snowfall; in this marine mud, the winter sediment from above showed up one color, the summer sediment another. I used a measurement technique that allowed me to pull a climate signal out of the alternating light and dark bands. But to confirm that those climate wiggles were real, I had to try to match what I saw with other records that climatologists were really sure showed a strong connection to the hot and cold climate swings of the past; enter Greenland's ice cores.
In 1999, when I was doing my research, the gold standards for such climate-record wiggle matching were ice cores from the Greenland Ice Sheet Project 2 (GISP2) or from the Greenland Ice Core Project (GRIP). These two projects were a kind of friendly arms race between two different teams—one led by scientists in the U.S. (GISP2), the other by researchers in Europe (GRIP)—but without all the cold war skulduggery. Starting at nearly the same time (the Americans got a one-field-season jump on the Europeans), the two projects, less than 20 miles from each other near the summit of the Greenland ice sheet, raced to the bottom of the ice.
In July 1992 Europe won. That team reached the bed nearly 10,000 feet below the surface and stopped at the end of the ice. When the U.S. group finished a year later, not only did its core reach deeper than 10,000 feet, but the scientists were also able to collect a five-foot-long core of some of the rarest rock in the world—rock from under an ice sheet.
These two deep climatic records became standards to benchmark other records against. My mud record stretched from the present back to about 52,000 years ago. I could take that record of wiggles from dark (cold world above) to light (warmer world above) and see whether the same temperature-related wiggles pulled from the ice core matched up. They did.
Many other climate researchers saw the same thing. In the three decades since these two cores were pulled from the ice sheet, tree rings, coral, cave deposits, other sediment s and ice cores from across the world have all been successfully wiggle-matched to the records.
But in all the years researchers spent hunting for ice and finding out all they could about its nature, they mostly neglected to interrogate the stuff the ice is sitting on. That is a critical gap in our knowledge that is just waiting to be closed. 'Those bed materials, whether it's sediment or hard bedrock contained within it, are the words, the stories of the history of the ice sheet—it's a book of information down there that we want to read,' says Jason Briner of the University at Buffalo, the other co-principal investigator of GreenDrill. 'The bedrock under ice sheets is the least explored remaining zone on Earth's surface,' Schaefer says. 'These are moon rocks for us—the most rare and the most hard-to-drill surface rocks anywhere on Earth—and we have practically no direct observations.'
Schaefer and Briner have spent more than a decade fixated on this deep gap in climate science. What they have already found is sobering. 'I have, for the first time ever in my career, datasets that take my sleep away at night,' Schaefer says. 'They are so direct and tell me this ice sheet is in so much trouble.'
The data that terrify him come from the rock collected in 1993 under the GISP2 ice core. The ice core went off to be immortalized in thousands of research papers as a centerpiece of climate science. The bedrock went into cold storage in the U.S. ice-core repository in Colorado. There it sat for almost two decades. In 2016 Schaefer, Briner and their collaborators exhumed the rock core and read it like a buried history book. They published a research paper in Nature entitled 'Greenland Was Nearly Ice-Free for Extended Periods during the Pleistocene.'
The Pleistocene, a period that includes the last ice age, stretched from around 2.6 million to 11,000 years ago, when woolly mammoths, saber-toothed cats and the first modern humans roamed over earth and ice. From that one sub-ice rock core, the researchers learned that during that epoch there were periods—at least one, possibly many—when the ice sheet was completely gone or nearly so. 'You do one data point, bedrock underneath the thickest part of the Greenland ice sheet, so you basically have to melt the entire ice sheet to make that spot ice-free,' Schaefer says. 'Even there the bedrock was telling us, 'Hell, yes, I was ice-free a lot over the last geological period.''
'It started what some people like to call the fragile Greenland hypothesis,' says Paul Bierman, an author and geoscientist at the University of Vermont. Bierman and others have found additional evidence to support the worrying idea. In 2023 he and his colleagues published a study that showed 'multiple lines of evidence' indicating much of northwestern Greenland was ice-free around 400,000 years ago. The concentration of carbon dioxide in the atmosphere then was less than 300 parts per million. Today we're at 428 parts per million.
The GreenDrill team is preparing to publish new findings that are even more unnerving for humanity. Caleb Walcott-George, soon to be an assistant professor in the department of earth and environmental sciences at the University of Kentucky, was a graduate student during the first two field seasons of the project. At a recent academic conference, he presented solid evidence that an area in northwestern Greenland three times the size of New York City and currently covered by ice a third of a mile thick was either completely or nearly completely ice-free as recently as about 7,000 years ago. That corresponds with a time called the Holocene Thermal Maximum, when temperatures were just a few degrees warmer on average than they are now. Walcott-George says that's within the range of warming we might experience by 2100.
Not long after Moravec sensed that the drilling rig was on the verge of core break, the team pulled its first sample of the season up from 165 feet below. Minutes later the core sat inside the capped inner core barrel, ready for inspection.
Walcott-George and Allie Balter-Kennedy of Tufts University stood shoulder to shoulder in a small, blacked-out tent originally designed for spearfishing pike over a frozen lake. The only light was a dim tangerine glow coming from a single LED strip taped to the ceiling. Balter-Kennedy and Walcott-George screwed off the drill head at the end of the barrel, tipped the tube up at an angle and gently shook it to get the material inside to slide out into the tray. This rock could tell them when it last saw the light of day. It also 'remembered' how long it had been buried. But that memory was delicate, and even a flash of sunlight could throw it off.
Certain minerals in the rock act like batteries by 'charging' when they are buried. Radioactive decay in elements surrounding the grains strips their electrons, causing the grains to luminesce, although the rocks don't visibly glow. 'We can determine essentially the charge rate, and by doing this we can figure out how long these quartz and feldspar grains have been buried,' Walcott-George says. But even seconds of sunshine can reset this signal, so every time a piece of rock is unearthed from below the ice sheet, they return to the blacked-out tent.
There is another source of stored memory in a subglacial stone, and it originates inside the hearts of dying stars. The cataclysmic explosions that mark the death of a star throw cosmic rays across the galaxy. Those rays blast their way to Earth, creating a cascade of elementary particles that buffet the planet's surface. 'When they interact with rocks, they create these nuclear reactions that create isotopes or nuclides that we don't otherwise find on Earth,' Balter-Kennedy explains. 'We know the rate at which those nuclides are produced. If we can measure them, we can figure out how long that rock has been exposed to these cosmic rays—or, in our field, how long that rock has been ice-free.'
It's called surface exposure dating, and it works by revealing the total amount of rare isotopes in the rock sample. Over time, periods of sun exposure and burial create on/off spikes in the total amount of nuclides in the rock, with exposed being 'on' and covered being 'off.'
If researchers take two of these nuclides—say, beryllium-10 and aluminum-26—and measure their relative levels along many feet of a rock core, they get what's called the decay clock. This clock runs down as each isotope decays at a different, predictable rate. When scientists see parts of the rock record where the clock has gained time, they know that the surface saw the sun. When the sample is buried, the clock slowly loses time in a countdown to zero cosmogenic nuclides.
The two methods allow the scientists to interview the bedrock, so to speak. 'You ask: When have you been ice-free? For how long? And how many times have you been ice-free in the recent geological past?' Schaefer says. But that day in the tent it appeared that there might be no bedrock to interview. The core they had pulled up wasn't quite right.
'Where's that smooth bed?' Walcott-George asked, referring to the solid bedrock pay dirt they were looking for.
'I feel like it's gravelly ice, and then ...' Balter-Kennedy trailed off.
'Dirty ice,' Walcott-George said, completing the thought.
They decided they'd try again tomorrow.
Approximately 5,500,000,000,000 tons. That is how much water weight the Greenland ice sheet has lost to the ocean since just 2002. Sequentially dumped into Olympic-size natatoriums, it would provide a personal 660,000-gallon lap pool for every person living in Africa and Europe—all 2.2 billion of them.
But how, exactly, future melt will bring more green to Greenland is one of the biggest questions that science has yet to answer. 'The scientific community right now does not know how the Greenland ice sheet disintegrates,' Briner says. 'We don't know what the mechanisms are and how long it takes for the ice sheet to get to its teeny-tiny state.'
In discussions of Antarctica, the word ' collapse ' is now often associated with the loss of ice through ice shelves such as the Thwaites, a floating extension of the Antarctic ice sheet. Nearly 75 percent of Antarctica's coastal ice is in ice shelves floating in water. But the fate of Greenland is believed to be tied to that of its ice streams, which are more like small tongues that ring the island and are confined by deeply carved fjords.
Dorthe Dahl-Jensen, a Danish ice-core climatologist, first came to the Greenland ice sheet in 1981. Back then, 'no one was talking about global warming,' she says. When she told people she was drilling ice cores for climate research, they assumed she was investigating when the next ice age would arrive. In her four decades of working on this ice sheet, Dahl-Jensen has seen changes happen in real time. One day in 2012 she was on the ice—and it rained. 'I saw it as a very pure sign of global warming that we actually got rain on the center of the Greenland ice sheet,' she says.
More recently Dahl-Jensen led research for the East Greenland Ice-Core Project, which in 2023 managed to pull a 1.5-mile-long ice core (and some subglacial mud and stone) from close to where the NEGIS begins. The entire process had taken eight years. 'When you look at the balance of the ice sheet and how much it has lost, half of the extra loss is from melt along the coast of Greenland, but the other half is from acceleration of the ice in the streams,' she says. Dahl-Jensen knows that ice streams are a big factor in sea-level rise, but she's also aware that we don't yet know how they behave. 'We are not capable of modeling them properly into our ice-sheet models,' she explains.
That is why the GreenDrill team wanted to get bedrock underneath the NEGIS from a site much closer to where it meets the coast. Measurements from each of these projects will feed into the mathematical models, which attempt to simulate how the real world works. 'We have so many gaps in our physical understanding of how an ice sheet actually responds,' Schaefer says, noting that current models have big error margins.
Ice-sheet models work much like the climate models we use all the time—the ones that predict tomorrow's weather. They use mathematics to simulate the interactions among real atmospheric phenomena: wind, pressure, moisture, thermodynamics, and lots more. They are reasonably trustworthy over hours to days because they are loaded with real data: historical data; measurements from weather satellites and balloons; and observations from land, sea and commercial aircraft.
Improving the ability of ice-sheet models to accurately predict how the sheet will respond to the warming it is experiencing now—and that yet to come—is no different. The models need data-based gut checks to make sure their predictions are informed and constrained by as much reality as we can feed into them.
Schaefer believes reducing the error will make ice-sheet models better tools for adapting to climate change. 'If you are a politician and you want to make New York City—or any city that is close to the ocean—sea-level safe, you need precise predictions of what is going to happen,' he says. And those predictions will become increasingly vital as the world moves deeper and deeper into its climate-warmed future—a future that those who study Greenland fear will be societally altering.
'Think about the mass migration that will happen if we melt all of the Greenland ice sheet,' Bierman says. 'That's not tomorrow—that's centuries from now and even millennia from now—but when that happens, that will be the biggest movement of humans ever because they'll lose their farms, they'll lose their cities, they'll lose their homes,' he says. 'It will be creeping and slow, but it will happen.'
The day after the heartbreak in the fishing tent, the team hit solid rock. It was what they had come for, and they found it just in time. A blizzard blew through camp hours later, shutting down drilling for the next two days.
When the work resumed, the team decided to try for a second core. This one would be half as deep as the first, so, the researchers reasoned, maybe they could get even more precious rock from under the ice to interrogate in half the time it took to get the first sample. All work had to be wrapped up within a week to leave them enough time to pack up for extraction. With good-enough weather, the twin-engine ski plane would be landing at the site, and it wasn't going to wait for anything.
Over the next two days they made good progress. Rather than setting up the drill tent all over again, they decided to chance a mostly unprotected drill hole. A small wind break was all that separated them from the wind and blowing ice. While Moravec, Harmon and Tanner Kuhl, the third and most experienced ice-drilling engineer, started again, the others fanned out onto the nunataks, dark peaks that broke through the ice-bound oblivion like the heads of whales surfacing through the ocean of ice. There Walcott-George, Balter-Kennedy and Arnar Pall Gíslason, the team's survival guide, used backpack-size rock drills to take a core from the surface of a nunatak. The rock was constantly exposed to sun and cosmic rays, and the luminescence signal and cosmogenic nuclides pulled from it would provide the baseline against which the under-the-ice-sheet rock cores would be compared. Just as it started to look like they might have this victory-lap sampling in the bag, a second blizzard blasted through the site.
'Let's get the hell out of here,' yelled Matt Anfinson, the camp mechanic. He emerged from the drill tent into a whiteout. The storm was still picking up. The drill tent, the only refuge aside from the mess and sleeping tents, was bowing ominously in the 50-mile-per-hour winds. It was time for the team to grope its way back to camp with only a line of red flags to guide it through the nearly zero-visibility conditions.
For the past three hours the group had been involved in a kind of mechanical open-heart surgery. The patients were two backpack drills that had stopped working during sampling on the nearby nunatak. The team had brought two to be safe; both had died. The drills lay on the worktable, guts exposed. After fiddling with the ignition coils, Anfinson ripped on the starter pulls. As one drill spun into high gear through smoke and sputter, he looked like an ice-field Dr. Frankenstein, gleefully and maniacally gazing on his reincarnation. It was a rare victory amid a 'weather daze,' as Harmon, the driller, called it.
Living through blizzards like these feels like what you'd expect inside a sensory-deprivation white-noise machine. This latitude sees no darkness in May and June, but without a break in the gale-force winds, the conditions outside are both bright and blinding. Wind-sculpted snowdrifts grow through the field camp like giant, icy fingers. They block the doors of sleeping tents and make walking treacherous; you either trip on a three-foot-tall snow wall that wasn't there hours before or fall off one into three feet of powder.
There was a cruel monotony to the continuous winds. They forced the crew into smaller and smaller circles of living—sleep tent to mess tent to bathroom tent and back. Barbara Olga Hild, the polar bear guard, fought through the long, bright nights to keep the electrified wire fence around the camp from being covered by drifting snow. Walcott-George sat in the mess tent brewing carafe after carafe of strong coffee and engaging in Arctic self-care, using superglue to seal his dry, cracked fingers against drilling fluid. Balter-Kennedy patched punctures and tears in her favorite polar bib and pored over her core-sample logbooks. Moravec and Harmon played cribbage for hours. Everyone skulked outside into the whiteout on rotation to fill an orange five-gallon cooler with snow to be melted on a camp stove for water (it is ironic how much effort it takes to make drinkable water when we are surrounded by ice).
Perversely, it was during the weather's harshest moments that people used to working on the ice opened up about why they seek out the cold and the isolation of polar work. 'The reason people go to the Arctic is [that] you can hear the silence,' Hild said. Dahl-Jensen, the Danish ice-core scientist, told me that the months of near-complete isolation from the rest of the world have become a prized part of the experience, worth any amount of cold and discomfort. 'We live in our camp and do our research, and the time where you can only focus on one thing is really wonderful,' she said. That feeling—of slowing down, of concentration—is something many on the team told me they miss when they're off the ice. 'I always dread the end of a field season,' Balter-Kennedy said. On the other side is the stark return to normal life, the avalanche of unanswered e-mails, the fact that things are different than when you left them.
When the storm finally cleared after three days, the team practically launched through the tent opening to get back to work. Because of the blizzard, they had just two full days to complete the new drill hole. The first core took a week to get, and that was without any weather delays. Everything had to go right now.
Just one day later the entire team was standing around the drill and taking in the last sample before packing up. The drill had burned through almost 70 feet of ice. The weather was sunny. The day felt unseasonably warm—about 15 degrees Fahrenheit above freezing—and the team easily cranked through the last drilling run. As the last rock core entered the bottom of the barrel, the sounds of the rock band Ween floated out onto the open ice.
The core came up clean. The team closed the hole with a cheer and a small pour of the Danish liqueur Gammel Dansk, or, as it was better known here, 'driller's fluid.' It wasn't for the crew. 'You were a good hole,' Harmon said as Moravec poured booze down to the bedrock.
Walcott-George hoisted the final rock core like a prize striped bass. Then, as they had done all season, he and Balter-Kennedy noted its lengths and features and stored it for transport, not yet knowing what story of Greenland's ice-free past, and our flooded future, it might tell.

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2 days ago
- Scientific American
What It's Like to Live and Work on the Greenland Ice Sheet
This story was supported by a grant from the Pulitzer Center. This story was made possible through the assistance of the U.S. National Science Foundation Office of Polar Programs. Rachel Feltman: For Scientific American 's Science Quickly, I'm Rachel Feltman. Five and a half trillion tons. That's how much ice has melted out of the Greenland ice sheet since just 2002. On supporting science journalism If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today. It's a number almost too large to wrap your head around. But if you took that much water and used it to fill Olympic-size pools—which hold [about] 600,000 gallons, by the way—you'd have a lap pool for every person living in Africa and Europe, all 2.2 billion of them. The reason we know this is that for more than 20 years, satellites have been watching and measuring the so-called mass loss from Greenland's ice sheet—one of only two ice sheets in the world. Antarctica is the other one. What science doesn't know is how the Greenland ice sheet might come apart. And that's a really important question to answer, since it has a total of 24 feet of sea-level rise still locked up in its icy mass. Today on the show we're talking to one of our own: Jeff DelViscio, the head of multimedia at SciAm and executive producer of the podcast. Last year Jeff ventured out onto the ice sheet for a month. He went with members of a scientific expedition whose sole goal was to drill through the ice to get the rock below, and he's going to tell us why that matters when it comes to Greenland and the future of the ice sheet. Thanks for coming onto the show, Jeff. Jeff DelViscio: Thanks for having me, Rachel. Feltman: So why did you go to Greenland? What was this expedition all about? DelViscio: This was a project called GreenDrill, and GreenDrill is primarily based out of two institutions, where there are two co-PIs—so principal investigators—who are working on it: one at Columbia University and one at the University at Buffalo. And they have pulled this project together that was meant to go into different parts of Greenland and selectively sample the ice sheet to be able to figure out what was going on with it: its state, its health and how they could push the science forward on what they understand about the Greenland ice sheet and how it's built and, ultimately, how it comes apart. Feltman: What was life actually like on an ice sheet? Do you feel like you were prepared, or were there any surprises that came your way? DelViscio: I was absolutely not prepared. This was my first reporting in a polar zone, and once you get there you realize that a big part of your safety and well-being really depends on the people who are there with you ... Feltman: Mm. DelViscio: And there was decades' worth of experience out there on the ice sheet, and we can talk about this, but it took a long time to actually get to where I was going, and that was a whole part of the process. But once I actually arrived on the ice sheet proper, I think the first day I was there, temperatures were right around –20 degrees Fahrenheit [about –28.9 degrees Celsius]. Feltman: Wow. DelViscio: And the first night I slept on it, I actually was at a place in the middle of the ice sheet, at a Danish ice-coring camp, in transit over to the, the final location where the GreenDrill team was doing their work, and they had these 6x6 [foot] tents called Arctic ovens—it was not an oven inside. But those were out right on the ice sheet. And they said, 'Well, camp is pretty full. You should probably go out and sleep in a tent because you need to get used to it. You're gonna be out here for a while.' And so I did that, and it was a real experience, that first night. DelViscio (tape): So I guess I kind of asked for this. I wanted to go here and do this story. It's fine [laughs]. It's just maybe a rough first go, but I can try to go to bed, see if I can get some sleep. This is what it is right now. This is good practice. There's actually a station here, so if I really get uncomfortable, I suppose I could go inside. That's not gonna be the case if we hit the field camp. Um, yeah, glorious reporting work in the polar arctic. Here we are. Goodnight day one on the Greenland ice sheet. DelViscio: It was about –20 outside and maybe about 10 degrees, 15 degrees better in the, in the tent, so all night about zero [degrees F, or about –17.8 degrees C], –5 [degrees F, or about –20.6 degrees C], –10 [degrees F, or about –23.3 degrees C], and it was also at about 8,500 feet [2,590.8 meters] on the top of the ice sheet ... Feltman: Mm. DelViscio: Which, you know, you're kind of on a mountain already; it's like being in the Rockies but on the top of a big, wide ice sheet. In every direction you look there's nothing—there's no features; there's nothing—and you're just laying on ice all night, and it, it was painful ... Feltman: Yeah. DelViscio: I'm not gonna lie about it; it was painful. And you have a sleeping bag that's rated at –40 degrees [F, or –40 degrees C], and you have a hot-water bottle that you put in to, to try to warm yourself up, but my face was sort of sticking out of the mummy-bag hole, and I would breathe and there would just be ice crystals forming on my beard and face ... Feltman: Wow. DelViscio: As I breathed out, so a little bit of a rough intro. But I did question why I was there. DelViscio (tape): Well, I made it through my first night. I wouldn't say it was pleasant—really cold the whole time [laughs]. That's—tough to get comfortable at any point. I don't know how people do this for long periods of time. Brutal, yeah. But I made it. DelViscio: But I did get through it, and there was a lot of experience, like I said, people who knew what they were doing, which really helped. Feltman: Yeah, well, you mentioned that getting out there took a really long time. How did you get there, and where did you end up? DelViscio: Yeah, so it's a process, and I had no idea how any of this worked before I, I got on the expedition, but typically, the U.S. military actually flies a lot of the science flights because there's a bit of history, and I—i n my feature you can read a little bit about that—because the U.S. military's been out on the, on the ice for decades for other reasons than ice-core research and climatology research but I went to a base in upstate New York, got on a big cargo plane ... Air Force announcer: In the event of a loss of pressurization issue, if you're to look over your left or right shoulder, there's a vertical rectangular panel on the wall ... DelViscio: Which flew to Kangerlussuaq, basically a staging location where all the science people kind of come in from all different parts of the world. You sort of sit there and you wait until the conditions are right so you can get onto another cargo plane ... DelViscio (tape): So this is it. We're in Kangerlussuaq, Greenland, and today we're shipping out to the ice. [CLIP: Sound of a Hercules C-130 cargo plane throttling up] DelViscio: Which then takes you and your whole crew out to, for us, a staging location, the Danish ice-coring site I mentioned, out in the middle of the ice 'cause it's too far to go directly to the site. DelViscio (tape): Okay, here we are: Greenland ice sheet. This is the EastGRIP [East Greenland Ice-Core Project] Danish site. It is cold. My camera's not loving this, but here we are. There's a station behind me and the sun just trying to peek through. Just came in on the Air National Guard C-130. They're pulling our stuff over. Here we go. DelViscio: Once you get on that smaller plane and, you know, manage all the weather and get out there in time, you sort of sit there and you kind of load up a smaller cargo plane ... [CLIP: Sound of a Twin Otter cargo plane throttling up] DelViscio: To take you yet another step, the final leg, to the GreenDrill site, which is out in the northeast part of Greenland—literally the middle of nowhere: hundreds of miles in every direction, there's just ice and you. [CLIP: Sound of wind blowing across the ice sheet at the GreenDrill camp] DelViscio: So it's a real production. It took about 20 flights for all ... Feltman: Wow. DelViscio: Of the people, logistics and gear. There's probably about 20,000 pounds' worth of gear, including the drilling equipment that we had to take. So it takes a week just to get there, and then you're sort of flat-out working once you actually do get there; the team knows that there's only so much time and there's a closing window, so it's kind of a scramble, but it's a long scramble just to get to there. Feltman: And where exactly are all those planes and gear going to? DelViscio: So they're going to a totally unpopulated part of the northeast Greenland ice sheet, but it was a really important location, and it was picked for a reason. Imagine this sort of large dome of ice. The way in which it actually moves—and it does move—is that snow falls on the top and sort of compresses, then spills out across the ice sheet, and part of that spill-out happens through these things called ice streams. And they're like a stream you would imagine in the water world, but they're just made of fully solid ice, and they're literally flowing away from the top of the ice sheet at a speed that's a lot faster than the surrounding ice, so you can actually see them in satellite data. And so we were positioned right at the edge of something called the Northeast Greenland Ice Stream, which drains about 12 to 16 percent of the ice sheet, so, like, basically over 10 percent of the water that's kind of going out and moving to the sea, getting into glaciers and then going into the ocean comes through this massive ice stream, which is really just this big tongue of ice moving faster than the surrounding parts of it. That location is really important to understand how the ice sheet loses its mass, and if you sample at just the right point, then you can understand, in this really critical portion of the ice sheet, exactly how that ice stream works in terms of keeping the ice either growing or shrinking, and right now it's really shrinking, so they wanna understand how these streams can play a part in pulling the ice sheet apart itself. Feltman: Yeah, let's talk more about the science. What kind of experiments are going on here? DelViscio: Yeah, so there's all of this ice, right? And in the past 60 years or so people have gone to the Greenland ice sheet to basically pull these long tubes of ice out of the ice sheet itself and use the ice as a record of climate change because ice is laid down yearly and it's basically like a tree ring ... Feltman: Mm-hmm. DelViscio: But in an ice sheet. And if you pull out large sections of it from the middle of the ice sheet, you can get up to [roughly] 125,000 years of climate: the snow falls, it compresses it captures the air that was above it at the time in little air bubbles, so the ice cores are these records of climate going into the past. Everyone was always focused on the ice, since the, like, '60s: 'What can the ice tell us about climate? How can we connect it up to other records of climate change and paleoclimate in the other parts of the world?' But no one, or very few people, looked underneath it. And the important part about being underneath the ice sheet is that the rock itself that's under the ice sheet tells you something about when it's had ice on it and when it hasn't, and when it hasn't is a really important part of that because if we're wondering about how the ice sheet breaks up, we really have to know how quickly that's happened in the past. And at this point science has very little idea about how that actually works. So what they did was: We were out there with these small drills, packed up in kind of containers. You take the drill and you drill all the way through the ice ... [CLIP: Sound of the Winkie Drill drilling through the ice sheet] DelViscio: And you're not happy when you get to the bottom of it—you stop, and then you keep going, and you pull the rock out from underneath the ice. The game here is to do measurements on that rock and see what it will tell you about when this place had ice and when it didn't. There is kind of a great quote from one of the co-principal investigators on the project that really kind of summed up why they started doing this. Here's what he had to say. Joerg Schaefer: [In] 2016 was the first study that was led by us that shows that you have these tools, these geochemical isotopic tools, to interview bedrock, and the bedrock actually talks to us. Since then it's clear to us, at least, that that's a new branch of science that is absolutely critical—it's really at the interface of basic geochemical and climate science and societal impact. It's one of these rare occasions that there is direct contact between basic research and scientific impact and questions like climate and social justice, so it's a very—scientifically, an extremely exciting time. [In] the same moment I must say that everything we have found out so far is very scary. And I kind of have, [for] the first time ever in my career, I have datasets that I—take my sleep away at night, simply because they are so direct and tell me, 'Oof, this ice sheet is in so much trouble.' DelViscio: That's Joerg Schaefer from Columbia University. Feltman: What was it about those datasets that he found so troubling? DelViscio: Sure, so I just talked about that long ice core that they pulled from the middle of the ice sheet and using that as a record. In the 1990s one of those was pulled at a place called GISP2, which is the Greenland Ice Sheet Project 2 site. It was an American site, and they went further than anybody else had in the past, and once they got through the entirety of that ice, about 10,000 feet worth of ice, they pushed the drill farther, slammed it down into the rock and pulled some rocks out. Now, the ice core went off to be in thousands and thousands of other papers connected to records all over the world; the rock underneath went to a freezer and got stored, and people basically forgot about it. Joerg Schaefer and Jason Briner of the University at Buffalo, in the early 2010s they realized that that rock could tell you something, and now they had chemical tools to analyze that rock in a way that it hadn't [been] before. And so they went back and got that rock, they tested it, and in 2016 they published a paper that showed: at that site in the middle of the ice sheet, their chemical tests told them that it was ice-free within the last million years. That means the whole ice sheet was gone. Feltman: Wow. DelViscio: And that was way quicker than anybody thought was possible. And so that spurred this whole next step, which was: 'If we got more of these rocks from different parts of the ice sheet, what else will it tell us about how quickly this happens?' Jason Briner: The bed of the ice sheet contains a history of the ice that covers it—basically the words, the stories of the history of the ice sheet. It's a book of information down there that we want to read if we can get those samples. DelViscio: That's Jason Briner. So that was the seed of this whole thing. So if you stick this soda straw down into the rock and you pull it back out, you can test multiple locations, and it could tell you, 'Here there was no ice then. Here there was no ice then. Here there was no ice then,' around the ice sheet as a way to sort of test ... Feltman: Hmm. DelViscio: How it sort of shrinks back to its teeny-tiny state. Feltman: And how do you get that kind of signal out of a rock? DelViscio: It's complicated [laughs]. It—you know, I wasn't a chemistry major in, in school; I was a geology major. But one of the researchers in the field, Allie Balter-Kennedy, you know, she has a good way of thinking about it. Why don't I just pull Allie in to talk about how this signal comes into the rock? Allie Balter-Kennedy: So there's cosmic rays that come in from outer space at all times, and when they interact with rocks they create these nuclear reactions that create isotopes or nuclides that we don't otherwise find on Earth. And we know the rate at which those nuclides are produced, so if we can measure them, we can figure out how long that rock has been exposed to these cosmic rays—or, kind of in our field, how long that rock has been ice-free. And so when you do that underneath an ice sheet, you get a sense of when the last time the rock was exposed and also how long it was exposed for, so it's a pretty powerful method for learning about times when ice was smaller than it is now. DelViscio: These nuclides are the signal inside the rock. If you can tell how much of it is in the rock and how quickly those signals should decay, if you see jumps in that signal, you can tell that ice was over top of it and it stopped the barrage from the universe, so it turned the signal on and off. Feltman: Hmm. DelViscio: And that's sort of how they look at the signal, is like: 'Is it on; is it off? Is it on; is it off?' And that tells you, in a way: 'There was ice over top, or there wasn't. There was ice over top, or there wasn't.' Feltman: Wow, yes, that does sound very complicated [laughs] but also very cool. Did the team end up actually getting what they were after? DelViscio: Yeah, so it was kind of down to the line. After all the traveling and all the logistics, and there was some weather and delays, and there [were] cargo flights that couldn't land, basically, everything got compressed into about three weeks on the ice at the site. That's not a whole lot of time to do what they were trying to do. It's a spoiler alert, but if you read the feature, you'll hear about exactly how this happened, but they did end up getting not just one of these samples, but two ... Feltman: Hmm. DelViscio: From two different sites, which you can sort of test against each other to make sure you got the right stuff. All the way to the last few days before extraction they were drilling, trying to get the rock samples. But there was this moment out on the ice, right towards when we sort of wrapped up, where I remember it felt unseasonably warm. [CLIP: Sound of the members of the GreenDrill team around the Winkie Drill] DelViscio: It was about 25 degrees [F, or about –3.9 degrees C], which is balmy ... Feltman: Yeah. DelViscio: On the ice sheet. And honestly, the, the drill was just, after going through a couple rounds where it was tough going, sort of sliced like, you know, a knife through hot bread down to the ice and got the rock out, and they got this beautiful long core. Caleb Walcott-George: Heavy! Elliot Moravec: That there's genuine rock core. Walcott-George: Oh, baby. DelViscio: I just remember, Caleb Walcott-George, who was one of the scientists on the expedition, just, like, hoisted it like it was, like, this prized bass. Feltman: Yeah. DelViscio: And there was sort of this shout all around the camp. Walcott-George: Oh, too late [laughs]! Tanner Kuhl: I was just baiting ya. DelViscio: And when they closed the hole they had this liquor called Gammel Dansk, which is this Danish liqueur, but they call it 'driller's fluid.' Moravec: There it is. Forest Harmon: You gotta lace it right down in the casing, dude. DelViscio: And they poured one down the hole to close it out as a way to sort of give the hole something back. Moravec: Bottoms up. Walcott-George: You wanna see something I made? Moravec: That's all she wrote. Kuhl: Well-done. DelViscio: It was this really clean finish to what had been a pretty stressful couple weeks, just trying to get samples back with the window of time closing. So it was a, a nice moment out on the ice and, you know, just had music playing, and it felt like not the end of the world in the middle of an ice sheet but a tight-knit science camp where things were going right. Feltman: Yeah, that must've been really cool 'cause I feel like there's not a lot of field work where, when you get the thing you're looking for, it's, like, sturdy and hoistable [laughs], so that's fun. DelViscio: For sure. Feltman: And I'm sure, you know, there's gonna be years of follow-up research on this data, but what are they learning from their time in the field? DelViscio: They had a, a site in another part of Greenland from the year before where they did the same kind of work, and they're just at the point at where they're publishing that. And what it looks like is that there's this place called Prudhoe Dome, which is in the northwest part of Greenland, where there was this big ice dome, and what those tests told them was: it looked very probable within the Holocene, so in the last 10,000 years, that the ice was completely gone there. Feltman: Hmm. DelViscio: And it was a lot of ice to take away that quickly. Again, it's, you know, you're sort of going from this 2016 paper, which says a million years ago it was ice-free—a million years is a long time. Feltman: Yeah. DelViscio: But even a sample in a place where there's a whole lot of ice in the northwest of Greenland and having it gone within the last 10,000 years, with climatic conditions that are close to what we're experiencing now, that puts it on a 'our threat' kind of level. Feltman: Yeah. DelViscio: Because ultimately, you know, if the whole of the ice sheet melted, that's 24 feet of sea-level rise. That means massive migration, totally changes the surface of the planet. But you don't need 24 feet to really mess some stuff up. So even five inches or 10 inches or a foot and a half is kind of life-changing for coastal communities around the world. Every amount of exactitude they can get on how this thing changes, breaks up and melts is just a little bit more help for humanity in terms of planning for that kind of scenario, which, given the state of our climate, seems like we're gonna get more melt before we get it growing back, so it's definitely coming—the, the melt is coming; the flood is coming. Feltman: Well, thanks so much for coming on to share some of your Greenland story with us, Jeff. DelViscio: Of course, I was happy to freeze my butt off to get this story for our readers and listeners [laughs]. Feltman: That's all for today's episode. Science Quickly is produced by me, Rachel Feltman, along with Fonda Mwangi, Kelso Harper, Naeem Amarsy and Jeff DelViscio. This episode was edited and reported by Jeff DelViscio. You can check out his July/ August cover story, ' Greenland's Frozen Secret,' on the website now. We'll put a link to it in our show notes, too. Shayna Posses and Aaron Shattuck fact check our show. Our theme music was composed by Dominic Smith. Special thanks to the whole GreenDrill team, including Allie Balter-Kennedy, Caleb Walcott-George, Joerg Schaefer, Jason Briner, Tanner Kuhl, Forest Harmon, Elliot Moravec, Matt Anfinson, Barbara Olga Hild, Arnar Pall Gíslason and Zoe Courville for all their insights and support in the field. Jeff's reporting was supported by a grant from the Pulitzer Center and made possible through the assistance of the U.S. National Science Foundation Office of Polar Programs. For Science Quickly, this is Rachel Feltman.


Scientific American
17-06-2025
- Scientific American
What Greenland's Ancient Past Reveals about Its Fragile Future
This story was supported by a grant from the Pulitzer Center. Inside a tent fastened to the surface of Greenland's ice sheet, the members of the GreenDrill expedition huddled around a drilling rig. The machine whined and shook as it spun. For days the drillers had been inching through ancient, solid ice to reach the rock below. Outside, the sun burned down through a cloudless sky. The wind, having tumbled down 4,000 feet of elevation from the domed summit of the ice sheet hundreds of miles to the west, charged over the surface in wavelike pulses. The tent shuddered like some mad bouncy house at the end of the world. The nine members of the expedition—ice and rock engineers, scientists, polar-survival specialists—knew they should be close to bedrock. But Forest Harmon, the driller working the handwheel, said he still couldn't feel the core break—the moment when the metal catcher inside the drill head separates the bedrock core from its earthly tomb. On supporting science journalism If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today. The GreenDrill site sat on the frozen edge of the Northeast Greenland Ice Stream, or NEGIS, a massive, moving tongue of ice that drains 12 to 16 percent of the ice sheet into the ocean. Upended and laid atop the contiguous U.S., it would look like a flowing mountain range more than a mile and half tall at its highest point and 20 to 30 miles across, extending from Boston to Washington, D.C. If the entire Greenland ice sheet melted, global sea levels would rise by about 24 feet. The NEGIS is how a good deal of that planet-altering flood would enter the sea. The sheet won't melt all at once, of course, but scientists are increasingly concerned by signs of accelerating ice-sheet retreat. A recent report showed that it has been losing mass every year for the past 27 years. Another study found that nearly every Greenlandic glacier has thinned or retreated in the past few decades. The NEGIS itself has extensively sped up and thinned over the past decade. Elliot Moravec, the mechanical engineer monitoring the drill-fluid pressure gauge, smiled, but only slightly. It seemed like something was about to go right, finally—in an expedition where almost nothing had before the team made it to the ice. So much in the weeks leading up to this moment had been uncertain. There were logistical delays and failed landings by military cargo planes. A more ambitious plan, which included a much larger drill and two different sample sites, had been scrapped. The project's two principal investigators were both forced to forfeit the field season at the last minute. One of them had come all the way to Greenland only to have to turn around. The other made the painful decision to not even try to make it to the ice. The rest of the team was marooned for weeks in Kangerlussuaq, a staging location on Greenland's southwestern coast, about 850 miles from the drill site. Then it had taken more than 10 flights over seven days to get them and tens of thousands of pounds of gear onto the ice. But at this moment, with just two weeks remaining in the expedition, their bit sat at the edge of discovery. The zone below was thought to hold within it a revelation: frozen in stone was a picture of this place but ice-free. Knowing the last time this area was actually green would help scientists answer a question of enormous consequence: Is the Greenland ice sheet even more fragile than we know? Since President Donald Trump announced his administration's desire to 'get' the world's largest island, Greenland has been the subject of sudden global attention. Climate change is exposing land formerly covered by ice, heightening political tensions on the island nation—and in the waters surrounding it as sea ice also disappears. But although the administration's plan to extract Greenland's natural resources is new, the American desire to occupy it, and pull value from underneath its frozen heart, is not. In 1956 and 1957 the U.S. Army Corps of Engineers Snow, Ice and Permafrost Research Establishment, or SIPRE, recovered the first long ice cores from Greenland. Europeans and Americans alike had been trying to cross and dig into the ice sheet for decades before then. The ' father of continental drift ' himself, Alfred Wegener, is still entombed there. Wegener made four expeditions to study Greenland's ice in his lifetime. During his final expedition, in 1930, he died out on the ice. Just before he became a part of the ice record, he wrote: 'We are approaching a new era of polar exploration characterized by the successful utilization of new technologies in a rational manner. Everything that we want to and can measure must be measured on the ground.' In 1956 American scientists were doing exactly that, but the reason they were there at all had as much to do with the cold war as it did with the cold ice. The government's real mission was to build Arctic capabilities so it could both operate and listen from somewhere much closer to the Soviet Union. The location where SIPRE pulled those first deep ice cores from was called Site 2, and despite its public science mission, it was also a top-secret radar installation watching 24-7 for Soviet threats. But the tense geopolitics allowed a scientific discovery that, until then, had seemed impossible: the recovery of deep ice cores that kicked off an international race to recover and interrogate deeper and deeper ice. Those ice cores, and all that would be collected after them, became a kind of high-resolution climatological bedrock on which much of our understanding of rapid climate change rests. Although it is difficult to count the number of ice cores in existence, adding up the length of ice in just the freezers owned by Denmark (Greenland is an autonomous territory of the Kingdom of Denmark) and the U.S. gives you more than 21 miles of ancient ice. Researchers have dated them, measured the pressure of their enclosed air bubbles, characterized the structure of their snow, detected ancient volcanic cataclysms in their particulate content, and more. The results have given us an indirect way to track the timing of large and abrupt shifts in climate as far back as 123,000 years ago in the case of Greenland and 1.2 million years ago for ice extracted from Antarctica. 'They are basically a backbone of climate science in terms of giving us these continuous, high-resolution climate records,' says Joerg Schaefer, GreenDrill's co-principal investigator. I have a personal 25-year history with one of these backbones. As an undergraduate researcher, I lived for a month on an oceanographic research vessel off Baja California. The mission was to collect sediment cores from the ocean floor. I spent hours and hours taking measurements—more than 30,000 of them—with my face pressed close to stinking, methane-rich mud. Like ice cores, the sediment cores had visible horizontal bands. Ice cores' bands come from seasonal variations in snowfall; in this marine mud, the winter sediment from above showed up one color, the summer sediment another. I used a measurement technique that allowed me to pull a climate signal out of the alternating light and dark bands. But to confirm that those climate wiggles were real, I had to try to match what I saw with other records that climatologists were really sure showed a strong connection to the hot and cold climate swings of the past; enter Greenland's ice cores. In 1999, when I was doing my research, the gold standards for such climate-record wiggle matching were ice cores from the Greenland Ice Sheet Project 2 (GISP2) or from the Greenland Ice Core Project (GRIP). These two projects were a kind of friendly arms race between two different teams—one led by scientists in the U.S. (GISP2), the other by researchers in Europe (GRIP)—but without all the cold war skulduggery. Starting at nearly the same time (the Americans got a one-field-season jump on the Europeans), the two projects, less than 20 miles from each other near the summit of the Greenland ice sheet, raced to the bottom of the ice. In July 1992 Europe won. That team reached the bed nearly 10,000 feet below the surface and stopped at the end of the ice. When the U.S. group finished a year later, not only did its core reach deeper than 10,000 feet, but the scientists were also able to collect a five-foot-long core of some of the rarest rock in the world—rock from under an ice sheet. These two deep climatic records became standards to benchmark other records against. My mud record stretched from the present back to about 52,000 years ago. I could take that record of wiggles from dark (cold world above) to light (warmer world above) and see whether the same temperature-related wiggles pulled from the ice core matched up. They did. Many other climate researchers saw the same thing. In the three decades since these two cores were pulled from the ice sheet, tree rings, coral, cave deposits, other sediment s and ice cores from across the world have all been successfully wiggle-matched to the records. But in all the years researchers spent hunting for ice and finding out all they could about its nature, they mostly neglected to interrogate the stuff the ice is sitting on. That is a critical gap in our knowledge that is just waiting to be closed. 'Those bed materials, whether it's sediment or hard bedrock contained within it, are the words, the stories of the history of the ice sheet—it's a book of information down there that we want to read,' says Jason Briner of the University at Buffalo, the other co-principal investigator of GreenDrill. 'The bedrock under ice sheets is the least explored remaining zone on Earth's surface,' Schaefer says. 'These are moon rocks for us—the most rare and the most hard-to-drill surface rocks anywhere on Earth—and we have practically no direct observations.' Schaefer and Briner have spent more than a decade fixated on this deep gap in climate science. What they have already found is sobering. 'I have, for the first time ever in my career, datasets that take my sleep away at night,' Schaefer says. 'They are so direct and tell me this ice sheet is in so much trouble.' The data that terrify him come from the rock collected in 1993 under the GISP2 ice core. The ice core went off to be immortalized in thousands of research papers as a centerpiece of climate science. The bedrock went into cold storage in the U.S. ice-core repository in Colorado. There it sat for almost two decades. In 2016 Schaefer, Briner and their collaborators exhumed the rock core and read it like a buried history book. They published a research paper in Nature entitled 'Greenland Was Nearly Ice-Free for Extended Periods during the Pleistocene.' The Pleistocene, a period that includes the last ice age, stretched from around 2.6 million to 11,000 years ago, when woolly mammoths, saber-toothed cats and the first modern humans roamed over earth and ice. From that one sub-ice rock core, the researchers learned that during that epoch there were periods—at least one, possibly many—when the ice sheet was completely gone or nearly so. 'You do one data point, bedrock underneath the thickest part of the Greenland ice sheet, so you basically have to melt the entire ice sheet to make that spot ice-free,' Schaefer says. 'Even there the bedrock was telling us, 'Hell, yes, I was ice-free a lot over the last geological period.'' 'It started what some people like to call the fragile Greenland hypothesis,' says Paul Bierman, an author and geoscientist at the University of Vermont. Bierman and others have found additional evidence to support the worrying idea. In 2023 he and his colleagues published a study that showed 'multiple lines of evidence' indicating much of northwestern Greenland was ice-free around 400,000 years ago. The concentration of carbon dioxide in the atmosphere then was less than 300 parts per million. Today we're at 428 parts per million. The GreenDrill team is preparing to publish new findings that are even more unnerving for humanity. Caleb Walcott-George, soon to be an assistant professor in the department of earth and environmental sciences at the University of Kentucky, was a graduate student during the first two field seasons of the project. At a recent academic conference, he presented solid evidence that an area in northwestern Greenland three times the size of New York City and currently covered by ice a third of a mile thick was either completely or nearly completely ice-free as recently as about 7,000 years ago. That corresponds with a time called the Holocene Thermal Maximum, when temperatures were just a few degrees warmer on average than they are now. Walcott-George says that's within the range of warming we might experience by 2100. Not long after Moravec sensed that the drilling rig was on the verge of core break, the team pulled its first sample of the season up from 165 feet below. Minutes later the core sat inside the capped inner core barrel, ready for inspection. Walcott-George and Allie Balter-Kennedy of Tufts University stood shoulder to shoulder in a small, blacked-out tent originally designed for spearfishing pike over a frozen lake. The only light was a dim tangerine glow coming from a single LED strip taped to the ceiling. Balter-Kennedy and Walcott-George screwed off the drill head at the end of the barrel, tipped the tube up at an angle and gently shook it to get the material inside to slide out into the tray. This rock could tell them when it last saw the light of day. It also 'remembered' how long it had been buried. But that memory was delicate, and even a flash of sunlight could throw it off. Certain minerals in the rock act like batteries by 'charging' when they are buried. Radioactive decay in elements surrounding the grains strips their electrons, causing the grains to luminesce, although the rocks don't visibly glow. 'We can determine essentially the charge rate, and by doing this we can figure out how long these quartz and feldspar grains have been buried,' Walcott-George says. But even seconds of sunshine can reset this signal, so every time a piece of rock is unearthed from below the ice sheet, they return to the blacked-out tent. There is another source of stored memory in a subglacial stone, and it originates inside the hearts of dying stars. The cataclysmic explosions that mark the death of a star throw cosmic rays across the galaxy. Those rays blast their way to Earth, creating a cascade of elementary particles that buffet the planet's surface. 'When they interact with rocks, they create these nuclear reactions that create isotopes or nuclides that we don't otherwise find on Earth,' Balter-Kennedy explains. 'We know the rate at which those nuclides are produced. If we can measure them, we can figure out how long that rock has been exposed to these cosmic rays—or, in our field, how long that rock has been ice-free.' It's called surface exposure dating, and it works by revealing the total amount of rare isotopes in the rock sample. Over time, periods of sun exposure and burial create on/off spikes in the total amount of nuclides in the rock, with exposed being 'on' and covered being 'off.' If researchers take two of these nuclides—say, beryllium-10 and aluminum-26—and measure their relative levels along many feet of a rock core, they get what's called the decay clock. This clock runs down as each isotope decays at a different, predictable rate. When scientists see parts of the rock record where the clock has gained time, they know that the surface saw the sun. When the sample is buried, the clock slowly loses time in a countdown to zero cosmogenic nuclides. The two methods allow the scientists to interview the bedrock, so to speak. 'You ask: When have you been ice-free? For how long? And how many times have you been ice-free in the recent geological past?' Schaefer says. But that day in the tent it appeared that there might be no bedrock to interview. The core they had pulled up wasn't quite right. 'Where's that smooth bed?' Walcott-George asked, referring to the solid bedrock pay dirt they were looking for. 'I feel like it's gravelly ice, and then ...' Balter-Kennedy trailed off. 'Dirty ice,' Walcott-George said, completing the thought. They decided they'd try again tomorrow. Approximately 5,500,000,000,000 tons. That is how much water weight the Greenland ice sheet has lost to the ocean since just 2002. Sequentially dumped into Olympic-size natatoriums, it would provide a personal 660,000-gallon lap pool for every person living in Africa and Europe—all 2.2 billion of them. But how, exactly, future melt will bring more green to Greenland is one of the biggest questions that science has yet to answer. 'The scientific community right now does not know how the Greenland ice sheet disintegrates,' Briner says. 'We don't know what the mechanisms are and how long it takes for the ice sheet to get to its teeny-tiny state.' In discussions of Antarctica, the word ' collapse ' is now often associated with the loss of ice through ice shelves such as the Thwaites, a floating extension of the Antarctic ice sheet. Nearly 75 percent of Antarctica's coastal ice is in ice shelves floating in water. But the fate of Greenland is believed to be tied to that of its ice streams, which are more like small tongues that ring the island and are confined by deeply carved fjords. Dorthe Dahl-Jensen, a Danish ice-core climatologist, first came to the Greenland ice sheet in 1981. Back then, 'no one was talking about global warming,' she says. When she told people she was drilling ice cores for climate research, they assumed she was investigating when the next ice age would arrive. In her four decades of working on this ice sheet, Dahl-Jensen has seen changes happen in real time. One day in 2012 she was on the ice—and it rained. 'I saw it as a very pure sign of global warming that we actually got rain on the center of the Greenland ice sheet,' she says. More recently Dahl-Jensen led research for the East Greenland Ice-Core Project, which in 2023 managed to pull a 1.5-mile-long ice core (and some subglacial mud and stone) from close to where the NEGIS begins. The entire process had taken eight years. 'When you look at the balance of the ice sheet and how much it has lost, half of the extra loss is from melt along the coast of Greenland, but the other half is from acceleration of the ice in the streams,' she says. Dahl-Jensen knows that ice streams are a big factor in sea-level rise, but she's also aware that we don't yet know how they behave. 'We are not capable of modeling them properly into our ice-sheet models,' she explains. That is why the GreenDrill team wanted to get bedrock underneath the NEGIS from a site much closer to where it meets the coast. Measurements from each of these projects will feed into the mathematical models, which attempt to simulate how the real world works. 'We have so many gaps in our physical understanding of how an ice sheet actually responds,' Schaefer says, noting that current models have big error margins. Ice-sheet models work much like the climate models we use all the time—the ones that predict tomorrow's weather. They use mathematics to simulate the interactions among real atmospheric phenomena: wind, pressure, moisture, thermodynamics, and lots more. They are reasonably trustworthy over hours to days because they are loaded with real data: historical data; measurements from weather satellites and balloons; and observations from land, sea and commercial aircraft. Improving the ability of ice-sheet models to accurately predict how the sheet will respond to the warming it is experiencing now—and that yet to come—is no different. The models need data-based gut checks to make sure their predictions are informed and constrained by as much reality as we can feed into them. Schaefer believes reducing the error will make ice-sheet models better tools for adapting to climate change. 'If you are a politician and you want to make New York City—or any city that is close to the ocean—sea-level safe, you need precise predictions of what is going to happen,' he says. And those predictions will become increasingly vital as the world moves deeper and deeper into its climate-warmed future—a future that those who study Greenland fear will be societally altering. 'Think about the mass migration that will happen if we melt all of the Greenland ice sheet,' Bierman says. 'That's not tomorrow—that's centuries from now and even millennia from now—but when that happens, that will be the biggest movement of humans ever because they'll lose their farms, they'll lose their cities, they'll lose their homes,' he says. 'It will be creeping and slow, but it will happen.' The day after the heartbreak in the fishing tent, the team hit solid rock. It was what they had come for, and they found it just in time. A blizzard blew through camp hours later, shutting down drilling for the next two days. When the work resumed, the team decided to try for a second core. This one would be half as deep as the first, so, the researchers reasoned, maybe they could get even more precious rock from under the ice to interrogate in half the time it took to get the first sample. All work had to be wrapped up within a week to leave them enough time to pack up for extraction. With good-enough weather, the twin-engine ski plane would be landing at the site, and it wasn't going to wait for anything. Over the next two days they made good progress. Rather than setting up the drill tent all over again, they decided to chance a mostly unprotected drill hole. A small wind break was all that separated them from the wind and blowing ice. While Moravec, Harmon and Tanner Kuhl, the third and most experienced ice-drilling engineer, started again, the others fanned out onto the nunataks, dark peaks that broke through the ice-bound oblivion like the heads of whales surfacing through the ocean of ice. There Walcott-George, Balter-Kennedy and Arnar Pall Gíslason, the team's survival guide, used backpack-size rock drills to take a core from the surface of a nunatak. The rock was constantly exposed to sun and cosmic rays, and the luminescence signal and cosmogenic nuclides pulled from it would provide the baseline against which the under-the-ice-sheet rock cores would be compared. Just as it started to look like they might have this victory-lap sampling in the bag, a second blizzard blasted through the site. 'Let's get the hell out of here,' yelled Matt Anfinson, the camp mechanic. He emerged from the drill tent into a whiteout. The storm was still picking up. The drill tent, the only refuge aside from the mess and sleeping tents, was bowing ominously in the 50-mile-per-hour winds. It was time for the team to grope its way back to camp with only a line of red flags to guide it through the nearly zero-visibility conditions. For the past three hours the group had been involved in a kind of mechanical open-heart surgery. The patients were two backpack drills that had stopped working during sampling on the nearby nunatak. The team had brought two to be safe; both had died. The drills lay on the worktable, guts exposed. After fiddling with the ignition coils, Anfinson ripped on the starter pulls. As one drill spun into high gear through smoke and sputter, he looked like an ice-field Dr. Frankenstein, gleefully and maniacally gazing on his reincarnation. It was a rare victory amid a 'weather daze,' as Harmon, the driller, called it. Living through blizzards like these feels like what you'd expect inside a sensory-deprivation white-noise machine. This latitude sees no darkness in May and June, but without a break in the gale-force winds, the conditions outside are both bright and blinding. Wind-sculpted snowdrifts grow through the field camp like giant, icy fingers. They block the doors of sleeping tents and make walking treacherous; you either trip on a three-foot-tall snow wall that wasn't there hours before or fall off one into three feet of powder. There was a cruel monotony to the continuous winds. They forced the crew into smaller and smaller circles of living—sleep tent to mess tent to bathroom tent and back. Barbara Olga Hild, the polar bear guard, fought through the long, bright nights to keep the electrified wire fence around the camp from being covered by drifting snow. Walcott-George sat in the mess tent brewing carafe after carafe of strong coffee and engaging in Arctic self-care, using superglue to seal his dry, cracked fingers against drilling fluid. Balter-Kennedy patched punctures and tears in her favorite polar bib and pored over her core-sample logbooks. Moravec and Harmon played cribbage for hours. Everyone skulked outside into the whiteout on rotation to fill an orange five-gallon cooler with snow to be melted on a camp stove for water (it is ironic how much effort it takes to make drinkable water when we are surrounded by ice). Perversely, it was during the weather's harshest moments that people used to working on the ice opened up about why they seek out the cold and the isolation of polar work. 'The reason people go to the Arctic is [that] you can hear the silence,' Hild said. Dahl-Jensen, the Danish ice-core scientist, told me that the months of near-complete isolation from the rest of the world have become a prized part of the experience, worth any amount of cold and discomfort. 'We live in our camp and do our research, and the time where you can only focus on one thing is really wonderful,' she said. That feeling—of slowing down, of concentration—is something many on the team told me they miss when they're off the ice. 'I always dread the end of a field season,' Balter-Kennedy said. On the other side is the stark return to normal life, the avalanche of unanswered e-mails, the fact that things are different than when you left them. When the storm finally cleared after three days, the team practically launched through the tent opening to get back to work. Because of the blizzard, they had just two full days to complete the new drill hole. The first core took a week to get, and that was without any weather delays. Everything had to go right now. Just one day later the entire team was standing around the drill and taking in the last sample before packing up. The drill had burned through almost 70 feet of ice. The weather was sunny. The day felt unseasonably warm—about 15 degrees Fahrenheit above freezing—and the team easily cranked through the last drilling run. As the last rock core entered the bottom of the barrel, the sounds of the rock band Ween floated out onto the open ice. The core came up clean. The team closed the hole with a cheer and a small pour of the Danish liqueur Gammel Dansk, or, as it was better known here, 'driller's fluid.' It wasn't for the crew. 'You were a good hole,' Harmon said as Moravec poured booze down to the bedrock. Walcott-George hoisted the final rock core like a prize striped bass. Then, as they had done all season, he and Balter-Kennedy noted its lengths and features and stored it for transport, not yet knowing what story of Greenland's ice-free past, and our flooded future, it might tell.
Yahoo
11-06-2025
- Yahoo
Greenland ice melted much faster than average in May heatwave: scientists
Greenland's ice sheet melted 17 times faster than the past average during a May heatwave that also hit Iceland, the scientific network World Weather Attribution (WWA) said in a report Wednesday. The Arctic region is on the frontline of global warming, heating up four times faster than the rest of the planet since 1979, according to a 2022 study in scientific journal Nature. "The melting rate of the Greenland ice sheet by, from a preliminary analysis, a factor of 17... means the Greenland ice sheet contribution to sea level rise is higher than it would have otherwise been without this heat wave," one of the authors of the report, Friederike Otto, told reporters. "Without climate change this would have been impossible," said Otto, an associate professor in climate science at the Imperial College London. The data from the May 15-21, 2025 heatwave was compared to the average ice melt for the same week during the period 1980-2010. In Iceland, the temperature exceeded 26 degrees Celsius (79 Fahrenheit) on May 15, unprecedented for that time of year on the subarctic island. "Temperatures over Iceland as observed this May are record-breaking, more than 13 degrees Celsius hotter than the 1991-2020 average May daily maximum temperatures," the WWA said. In May, 94 percent of Iceland's weather stations registered record temperatures, according to the country's meteorological institute. In eastern Greenland, the hottest day during the heatwave was about 3.9C warmer compared to the preindustrial climate, the WWA said. "While a heatwave that is around 20 degrees Celsius might not sound like an extreme event from the experience of most people around the world, it is a really big deal for this part of the world," Otto said. "It affects the whole world massively," she said. According to the WWA, the record highs observed in Iceland and Greenland this May could reoccur every 100 years. For Greenland's indigenous communities, the warmer temperatures and melting ice affect their ability to hunt on the ice, posing a threat to their livelihood and traditional way of life. The changes also affect infrastructure in the two countries. "In Greenland and Iceland, infrastructure is built for cold weather, meaning during a heatwave ice melt can lead to flooding and damage roads and infrastructure," the WWA said. In Greenland, the higher temperatures coupled with heavy rainfall can have numerous consequences on nature. In 2022, higher temperatures caused the permafrost to thaw, releasing iron and other metals into numerous Arctic lakes, it said. Health and hygiene can also be affected, as rural Greenlandic households often lack sewage systems. cbw/po/giv