Unexplainable - Ice Sheet Time Machine

Episode Date: August 27, 2025

The US military carved a tiny city into the Greenland ice sheet. What they found, and lost, and found again, and what it tells us about climate change. Guests: Paul Bierman, geoscientist at the University of Vermont and author of When The Ice Is Gone; Richard Alley, geoscientist at the Pennsylvania State University For show transcripts, go to ⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠vox.com/unxtranscripts⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠ For more, go to ⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠vox.com/unexplainable⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠ And please email us! ⁠⁠⁠⁠[e-mail]⁠⁠⁠⁠ We read every email. Support Unexplainable (and get ad-free episodes) by becoming a Vox Member today: ⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠vox.com/members Learn more about your ad choices. Visit podcastchoices.com/adchoices

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Free of charge. BetMGM operates pursuant to an operating agreement with Eye Gaming Ontario. Blow the surface of a giant ice cap. A city is buried. In the late 1950s, the U.S. Army kicked off a project that sounds like something out of science fiction. As part of man's continuing efforts to master the secrets of survival in the Arctic, the United States Army has established an unprecedented nuclear-powered Arctic research center. This is the story of Camp Century, the city under ice.

Camp Century was a research base, carved, into the Greenland ice sheet, about 800 miles from the North Pole. A geoscientist named Paul Bierman told me all about it. The layout was very much like a city grid. The basic concept was simple. There was one long street that was about 1,000 feet long down the middle, and then tunnels branching off the sides. A series of lateral trenches housing complete research, laboratory, and test facilities.

Some of the tunnels held the mess hall. Everything from steak to fruit salad. Some of those tunnels held the latrines. Here, there are showers for all. Some of those tunnels held barracks. It also has a small chapel for regular religious services. I think you have to imagine yourself dressed in clothing from the early 1950s. And you have to imagine the magazine ads.

And you have to imagine these sort of frightening movie titles and posters of the communists coming to take over America. That's the milieu. That's the cultural setting in which camp century is designed and thought about. The U.S. was about a decade into the Cold War at that point. And they were worried. They were worried about the Russians attacking North America, right? And so Greenland is the gateway from the Soviet Union to North America. They wanted to understand more about the snow and the ice so they could move materials and troops across it or even potentially hide missiles in it.

And so that's a big reason why they built this elaborate research base to unlock the ice's secrets. So many of their studies were basic science in the behavior of snow, and we still use what the Army learned back 50, 60 years ago to understand how ice sheets moved today. But they had another motivation for digging into the ice, because even in the 1950s, people thought the climate might be warming. And there were people even back then who thought, could this be human-induced climate change? There were other explanations put forward, like sunspots and orbital wobbles. But the question kicked off a quest, a quest that pulled up answers we are still learning from to this day. This project to drill down and then pull up a long tube of ice. Scientists call it a core.

Something that's four, five, six inches in diameter, and then stretches the depth of the ice sheet, and at Camp Century, the depth of that ice sheet is almost a mile. The scientists wanted this mile-long core of ice because they realized that a snow fell and piled up in layers year after year on this ice sheet, it trapped little traces of the world inside it. Everything from atmospheric gases to volcanic gases

to volcanic fallout. So each layer of snow turned into ice was like a page in a big record of Earth's history. A record dating back at least thousands of years. They actually didn't know how far that record went in the debates

in the sort of formal and very informal literature are fascinating. There's some popular science articles that say, wow, this ice could be thousands of years old. Wouldn't that be amazing? And the scientists were also curious about what was under the ice sheet. Will there be explosive packets of gas down there that have accumulated through time?

Will there be water? Will it be frozen? It was the equivalent of landing on the moon at that time. Unfortunately, it turns out that drilling all the way through a mile of ice and then pulling it up section by section or like cylinder by cylinder is not all that simple. Their first idea was, well, why don't we just melt through it? And the description would be like melting your way through a barrel of butter. That sounds easy, right? But it turns out it wasn't so easy because you're melting your way through the ice. Okay, that works until you figure out how am I to get rid of the water?

And how am I going to keep that hole open so it doesn't collapse? And what if the cable I have my drill on breaks? And what if I get the drill heads stuck? The drillheads did, in fact, get stuck. In an oral history years later, one of the researchers, this guy named Herb Uita, talked about how the drill got stuck several hundred feet in the ice, which then forced them to start the process all over again. By the way, each time we couldn't retrieve or maintain the hole,

well, it was a major operation because you had to move the winch and everything and start a new hole. And remember we were down in this trench there, and our space was sort of limited. So it was a major concern. So we did start another hole, and lo and behold, it's 750. feet. We lose a part of the drill, and that was the end of that hole. So it was just one heartbreak after another for those couple of years. They were able to bring up material, but they weren't

able to get to the bottom of the A sheet. Years went by without success. Finally, we've got to start considering something else. They wound up pivoting to a different drilling technique, one that involved grinding instead of melting. Long behold, it, well, that would the stroke getting going, but we finally got it on and worked like a churnum. In 1966, as Camp Century was winding down its operations, the researchers did finally hit the bottom of the ice sheet. And they didn't stop there. They were also able to drill into the sediments under the ice sheet and pull up some of that material, too. Probably the most satisfying moment of my life. Oh my career. Of my career. It turned out that the ice from this

score held not just a record of the last couple thousand years, but instead a record of around 100,000 years of Earth's climate history. And that record helped rewrite our understanding of both our past and our future. The ice was revolutionary. A fellow named Willie Dansgaard really pioneered the study of the water molecules in the ice and how those water molecules could be used to tell about the history of climate. And so by analyzing the water molecules, Willie and his group could determine, with reasonable accuracy, the temperatures in the past.

Willie Dansgard's work on the ice actually challenged some fundamental things people had assumed about Earth's climate. Scientists sort of thought that Earth's temperature shifted slowly and gradually. But this ice suggested, no. Temperatures could change pretty abruptly. It opened up this window to the past. that now dozens and dozens of ice cores have exploited to understand climate around the world. Dan's Guard was not the only scientist who analyzed this ice core from Camp Century.

In the years and decades after it came out of the ice sheet, many scientists studied samples of this ice and wrote papers about it. And they learned all kinds of things. They learned when volcanoes erupted because the dust and the acid from those volcanoes would land on the snow in Greenland and become ice. They learned about changes in the mountain. of sea salt coming off the ocean. They learned about changes in climate. Over time, researchers figured out how to analyze little gas bubbles trapped in the ice,

which were kind of like bubbles of ancient atmosphere. And that meant they could see how much of any given gas had been present when things were hotter or colder on Earth. And so this ice, along with other ice cores, helped scientists show how greenhouse gases in the atmosphere can lead to warming. All to say. This core just keeps on giving.

This long tube of ice helped us learn a lot. But even though all these scientists were doing all this work on the ice itself, they were kind of ignoring another potential source of information, the stuff that came up from under the ice. Until about five years ago, there were three publications on the frozen soil. As Paul puts it, we have significantly less material from underneath Greenland's ice sheet than we do rocks from the moon. So this frozen soil should be pretty precious.

And yet... I think the focus of the community was almost laser on the ice and not on the stuff beneath it. In fact, there was so little intention being paid to the soil from underneath Camp Century that it somehow kind of disappeared. There's a mystery around this that many people have taken to their graves, and we will probably never know exactly what happened. But basically, over the years, the ice cores were moved to different storage facilities.

So first one in Buffalo and then in the 90s to a facility in Colorado. And soon after, people noticed that the bottom of Camp Century and the bottom of an ice core called Bird Station from Antarctica never made it to Colorado. Paul spoke to some people who thought they'd ended up in Denmark, maybe, but nobody really seemed to know. Most people, the people I talked to when I was being trained and I occasionally thought about Camp Century in the years after,

And I asked them, they said, ah, those cores are gone. That's, they're just not around anymore. Losing track of any sample is a shame. But in retrospect, this sample in particular had a lot to tell us. More on that after the break. It's all about you. And when you fly with Virgin Atlantic in their upper class cabin, they take the VIP treatment to the next level.

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Trying any salsa is like playing Russian roulette with a flame thrower. Luckily, Jeff saved with Amazon and stocked up on antacids, ginger tea, and milk. Habaniero? More like habanier, yes. Save the everyday with Amazon. I wish I loved anything, as much as Richard Alley loves ice. It's just gloriously beautiful. If you've ever looked at a glacier flowing down a mountain, if you've ever seen a time lapse of a glacier flowing, or looked at the snowflakes that go into it, or peered down a moulon, this giant hole that the stream mills down on a mountain glacier

that goes to the bottom of the ice. I mean, just the glory and the excitement. Fortunately, Richard has had lots of opportunities to study his favorite subject. He has been studying ICE as a scientist and a researcher ever since he was in undergrad. in the 1970s. I started summer after freshman year. Oh, so you know a thing or two about ice. Coming up on 50 years.

And it was actually a great time to get into ice research. The Camp Century Corps had come out of the ice sheet. And that Corps, along with ice from another site called Di3, wound up raising all kinds of interesting questions about these abrupt changes in past climate. And when I first began, became an assistant professor trying to work my way towards tenure, I was fortunate enough to get involved in one of the projects that came out of. Camp Century and Di3 have told us what we have to know. Well, let's go find out. Finding out involved two separate drilling teams,

drilling two new cores in the Greenland ice. Those cores came up in the 1990s, and the researchers on each team spent a bunch of time checking them out. And we find all these abrupt climate changes and oh my goodness it's just wonderful, wonderful science and duplicated across the two cores and it's pound on the table. This is right. We got it nailed. But the sterling also brought up some of those rarer than moon rock sediments. And these rocks did not get lost. They got some sustained research attention. Scientists wound up looking at them to see if they'd gotten zapped by cosmic rays. So we are, you know, getting zapped by cosmic rays. And, And cosmic rays occasionally cause damage.

And some small fraction of cancers are probably caused by cosmic rays ripping through us in some way. Oh, just one more thing to worry about. It's small. It's not, you know, there's lots and lots of bigger things to worry about in that world. But nonetheless, this happens. And cosmic rays also rip through rocks and damage their. their atoms. Now, the effects of the zapping kind of fade over time. So scientists have found a way to basically search rocks for weird damaged atoms and see, were they out in the open recently?

Like, were they close enough to the surface to get zapped? And when this was first measured in the 90s, it was right at the edge of what was doable. But by the 2010s, the technology was more advanced. And it showed researchers that, yes, the rocks from under the ice did, in fact, seem to have been zapped. And fairly recently, too, or like, geologically recently. They couldn't put an exact date on it, but their research suggested that sometime in the last million or so years, this spot was ice-free. Now, this was just one spot, right? but it was near the middle of the ice sheet. So that could mean that if this spot was ice-free,

then much of Greenland was also ice-free at that time. And that would be a pretty big deal. Greenland's ice sheet is absurdly large. Like, it's almost two miles deep at some points. That's a mountain of solid ice. And for a long time, people thought that mountain of ice would be hard to melt, or that our world would have to be hotter for that to happen. Except, if you look back across this million-year window...

There's just no time that it was lots warmer than today. But somewhere when it was a little warmer than today, or maybe just equal to today, but it stayed that way for a while. Greenland lost most of its ice. which means it is possible the temperatures right now are either hot enough or almost hot enough to melt most of the ice on Greenland if given enough time. Richard told me that the notion that Greenland's ice was super hardy was already kind of on thin ice by the time this paper came out.

But the paper was new evidence that Greenland's ice might be pretty sensitive to temperature changes. And look, if the ice melts, it's not like it will all melt tomorrow, right? It could take a long time. But if it does melt, it would mean a lot of sea level rise. Like a lot, a lot of sea level rise. Like potentially more than 20 feet of sea level rise just from Greenland's ice. We talk about the huge problems that could come from three feet of sea level rise. 20 feet could mean, coastal cities underwater and millions and millions of people potentially displaced.

And it's hard to deal with. It really is. This is a tension that I think all climate scientists deal with because we love doing science. And we love it when we learn something new. And we love it when things fit together

and you can look at the data coming out and saying, wow, wow, this is so cool. It's so exciting. It's so big. It's, oh, bad word at all anyway. It's so bad. Now, the news was already pretty bad, right? Like, even before this paper came out, some scientists put out another paper that showed that at other moments when the world was around as warm as it is now, there was a lot of ice melt at the polls. It's just that this cosmic Gray's apping paper showed that the rocks beneath the ice could give us more information here, more specifics. And so Paul Bierman, our geoscientist slash camp century enthusiast, he's really

excited to study those rocks further. Since the campcentric core came out, the focus has been on ice. And it's been on ice in Greenland. It's been on ice in Antarctica. Now we've opened this large, window that says we can learn a whole lot of different things if we look at the material below the ice. So this has no value judgment on looking at the ice at all. That's incredibly important. It's opened up this new pathway to say, well, okay, let's also start looking at the stuff beneath. The problem, of course, is that we don't have a ton of stuff from beneath the ice. And some of what we did have, we lost somehow. When Paul first got interested in all this, the bottom of the Camp Century Corps was still MIA.

Until, all of a sudden, it wasn't. One day, a few years ago, researchers from Denmark gathered some scientists, including Paul and a geochemist named Jorg Schaefer, who'd been a lead researcher on the cosmic ray zapping paper. And they took them on a little field trip out to their new ice core storage facility on the outskirts of Copenhagen.

This is April. It's a beautiful April day in Copenhagen. It's warm. The flowers are out and all this. And we go into minus 27 Celsius wearing what was not enough clothing. And I had a little, this picture of me with a little hat over my bald head and tiny little gloves for like skiing in the spring and one jacket. They walked in. The scientists they were with told them a little bit about the new facility. And then he waves at like three of us. And he says, come over and look at this. And sitting in the corner with this cardboard box filled with glass cookie jars filled with brown lumps of frozen soil. So that is the first time I saw the Cam Century Corps. And I can feel this right now.

And it's the same feeling I had then where this little shiver runs up your spine of, oh, my, what am I looking at? And the three of us, Yorg and I and the phone name Nikolai, sat there, stood there. Must have been 20 minutes shivering, holding these things and just staring at it and looking at each other like, is this real? Is this here? It was real. One of the Danish researchers told Paul that the samples had been rediscovered when, the new freezer was built. Paul and York were, obviously, itching to start analyzing this mud, and the Danes agreed to share it.

And in July of that year, at the University of Vermont, showed up a huge foam box filled with freezer packs and two pieces of sediment core that you could hold in your hands. They were half rounds. They'd taken the cylindrical core, and they cut it down the middle, and they'd sent us half, and it was, oh, less than a pound of material. They popped the samples in the freezer, and then the next day, they took them out to photograph them. We opened them up, and the stench that greeted us was overwhelming.

They smelled like diesel fuel because the drilling had been done in diesel fluid, with dry cleaning fluid added for good measure. So we immediately put them back in the freezer, and then we thought about this, and we ended up melting them in fume hoods where they were ventilated, so we didn't have to breathe this. And the next morning we came in, in, they were melted. I had a little time off from the students, and we started taking apart. And the way we took them apart is because at this point, they were lumps of mud, right?

The frozen, they just turned into mud. And we took that mud, and we put very clean water on it, and we put it through a stack of sieves. Those are brass. Think about like the screen on your screen door, but in different sizes, like big screens, medium screens, little screens. And we started washing them, and we kept every drop of water and every little piece of dust out of there because we didn't have much, and we had all these people who needed bits of it. And we sorted them all by their sizes, and we had bins of water all labeled sitting in our laboratory, and we took a break. And we came back, and I looked at one of the bins, and there were things floating in it. And I looked at this bin, and I looked over at Drew Christ, who was a doctoral

student working with me at the time, and I said, Drew, they're fossils in here. And he looked at me, and he let out this sort of string of expletives. Like, you're nuts. You've been out in the heat too long. And I said, no, I think they're fossils floating in here. And so we took a little pipette and we sucked out these little black bits and we put them on a little microscope slide and I handed this thing to Drew. And he popped it under the scope and there was dead silence for about 30 seconds. And then this scream, more expletives and a lot of joy. And we were all the three of us who were in there and undergraduate was with us. Kept looking down the scope and there were twigs and there were leaves.

were little bits of moss. And all those little floating things turned out to be fossil material. And we had no clue how old it was. But it looks like if you ever been swimming in a mucky pond and, you know, you pull your feet back up out of that mucky pond bottom and there's little bits of leaves and twigs on your feet, that's exactly what this looked like. So we had found a frozen ecosystem. And it turns out now there's soil fungus in there. There's bugs. There's little midges.

There's dozens of different forms of life. This was clear, hold a twig in your hands type evidence that this spot near the edge of Greenland was once ice-free. And this mud and these fossils, they gave Paul and his fellow researchers a lot of information. They were able to put precise dates on them, which showed them when this spot was ice-free, for example. And that gives them more precise information about what conditions on Earth were like at the time of this melting. There's still a lot more to be learned about how sensitive Greenland ice is, but just recently, more projects pulled up more ice and mud from the Greenland Ice Sheets, so people are investigating these questions further.

Basically, we have come a long way from the days when scientists would just let soil from under the ice sheet languish, kind of undervalued. As Richard Alley puts it, engineers have come up with plans to, to protect our cities from sea level rise? And they're looking at potential costs in the billions or even the hundreds of billions. And if we have the sea level rise wrong, if it doesn't rise as much as they build for, they're wasting money building,

and they're losing ecosystem services and they're losing recreational services, if it rises higher than they're building for and they don't respond really fast, we have Katrina's. We have cities flood. and lives lost in properties and, oh, it's horrible. And so the value of information on this is so huge.

If somebody said, let's spend 1% of the cost of defending three cities on getting this right, we wouldn't know what to do with that much money. We don't have the people because we haven't been able to advise the students and bring them along. So this is a place where the value of information is just immense. And there's a lot to do. When the U.S. Army abandoned Camp Century in the 1960s, they didn't really clean up after themselves. They left behind tens of thousands of gallons of sewage and diesel fuel

and even nuclear waste from the small reactor that they brought into power their city. The assumption was that all that waste would just stay trapped in the ice for the foreseeable future, buried under the snow. Now, as Greenland melts, or realizing that that's probably not the case. And so, in some ways, Camcentury feels to me like a representation of both my frustrations and my hopes when it comes to the future. On the one hand, it is very frustrating to me that researchers went up there and made a big mess for future generations to clean up. But on the other hand, the whole project is just such an amazing feat of science.

and engineering. We are still learning things from samples collected there. It gives me hope, even in this time when funding for climate research is being slashed, to think that we as a species are really good at doing impossible-seeming things. That we can figure out how to carve a city into the ice or drill a hole a mile down into it. And so, hopefully, we can also. figure out how to clean up after ourselves. If you want to read more about Paul Bierman's work, or the history of ice scoring, or the weird wonders of Camp Century, check out his book, When the Ice is Gone.

This episode was produced by me, Bird Pinkerton. It was edited by Jorge Just with help from Julia Longoria. Meredith Hadnott runs our show. Noam Hassanfeld makes our music. Christian Ayala did the mixing and the sound design. Melissa Hirsch, check the facts, and I am always, always grateful to Brian Resnick for co-creating the show. I'm also very grateful to Andrea Dutton for her time. She really, really helped me understand a lot about sea level rise.

And the oral history recording of Herb Uwita came from the Bird, Polar, and Climate Research Center Archival Program, which is part of the Ohio State University Libraries. We will link to it in the transcript. If you have thoughts about Camp Century or thoughts about ice or thoughts about pretty much anything, write in or send us a recording. We are at Unexplanable at Vox.com and I truly love hearing from you all. If you want to support the show and help us keep making it, you can join our membership program. It is at Vox.com slash members. You'll get ad-free podcasts.

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