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Lost Cold War Ice Core Reveals Greenland's Ice Free Past, Could Provide Key Data As Planet Warms

The Greenland ice sheet.
Joshua Brown
University of Vermont
Ice cores drilled by the U.S. military during the Cold War may hold key information about what happens when a block of ice the size of the Greenland ice sheet, shown here, melts rapidly.

It’s not often that things that happened a million years ago are news today, but a new study published this week about Greenland’s ice sheet seems to be the exception to that rule. The study, conducted by an international team of scientists and coordinated by two University of Vermont researchers, unearthed well-preserved fossils of plants which grew in Greenland during warm periods within the last few million years. The findings indicate Greenland’s ice sheet melted entirely and re-formed at least once in the past million years.

That news has big implications for how we respond to human-caused climate change, which is causing the Greenland ice sheet to melt again.

VPR’s Henry Epp spoke with UVM postdoctoral researcher Drew Christ and geology professor Paul Bierman, authors of the new research, about what this means for the planet today. Their conversation below has been edited and condensed for clarity.

Henry Epp: I want to talk about your research process here, because it’s almost like something out of a James Bond movie. These soil samples were taken from a US military base in Greenland in the 1960s. Can you tell us about Camp Century and why it was there?

Drew Christ: Camp Century seems like science fiction. So back in the 1960s, at the height of the Cold War, the U.S. military was really worried about what was going to happen in the Arctic because it was the most direct path between the Soviet Union and the United States for nuclear missile strikes. And so, they started building up military bases in Greenland. And one of their projects was Camp Century, where they built a military base inside of the Greenland ice sheet in a series of ice tunnels to see if they could ultimately store nuclear weapons inside of the Greenland ice sheet.

They soon discovered that that wasn't possible because the ice would crush everything, but one of the projects that they did to try to learn about how ice behaves was drilling ice cores.

And these ice cores that they drilled ended up leaving a much more lasting environmental legacy because we learned about how Earth's climate has changed in the past. And now looking at the sediment from the very bottom of this ice core that was lost for decades in a freezer in Copenhagen, we're beginning to understand the last time the Greenland ice sheet melted away and raised sea level.

Two men hold samples in a laboratory with rubber gloves.
Credit University of Vermont, Courtesy
Researcher and paper author Drew Christ with student Landon Williamson in the laboratory.

And so, when you got your hands on these soil samples, what exactly did you find? What did it look like?

Christ: We received them in the lab, in the geology department at UVM. And it was for me, as a climate scientist, like holding the Holy Grail because it's from the very first ice core and it's just remarkable to see how well they were preserved. What was really surprising, and I know Paul agrees with me, is that when we started to take the sediment apart to do our analyses as we had planned to do, we started to notice these little floating black specks in the rinse water. We were washing the sediment in and we looked at it under the microscope and they were frozen plant fossils.

Paul Bierman: Drew is downplaying the drama a little bit there. We were sitting in a very average University of Vermont lab with fume hoods running and sieves and water and this muddy sediment. And in the little bowl of water, we were saving everything, because there is less of this material, as Drew is fond of saying, than there is of moon rocks on the planet.

And so, we were saving every last ounce of this stuff. We had a bucket that was full of this this dirty water, and we noticed these little black flecks and we were bantering between ourselves over what they might be.

And I picked up a pipette and tweezers and a filter and I pulled some of the stuff off and I handed it to Drew and said, “Look at this under the microscope. I bet you're going to be surprised.” We were just laughing at each other, the undergraduate student, Andrew and myself, and he pops it under the microscope and literally screams when he sees what’s under there, because it was a leaf and a twig and what looked like a little seed.

And we had no idea we were going to find a frozen ecosystem in this muddy sediment from the bottom of an ice core. That is the first time this has ever happened.

And the importance of that is now: Not only do we know that within the last million years, the Greenland ice sheet disappeared, but we know it was warm enough when it disappeared to support a tundra ecosystem there. And that's pretty revolutionary stuff.

"... We had no idea we were going to find a frozen ecosystem in this muddy sediment from the bottom of an ice core. That is the first time this has ever happened." - Paul Bierman, geology professor, University of Vermont

And what it points us to, is buried under the Greenland ice sheet is a history of the climate of the North Atlantic and the Arctic, if we know where to go find it.

We are headed into this uncharted territory right now, warming our planet. And our best analogs for how the planet might behave are how it behaved in the past. And this gives us an analog for what the planet did in the past when it warmed up.

People might be hearing this and thinking, well, OK, the Greenland ice sheet has melted before. So really, how is that any different than if it were to melt today? And shouldn't that maybe be reassuring in some way that we've been through this before? And, you know, so if it happens again, is that a big deal?

Christ: Well, the last time that the Greenland ice sheet melted, there weren't 7.5 billion people on the planet and there weren't massive cities with all the infrastructure and trade. And so, if the Greenland ice sheet is capable of melting away under natural climate change in the past and now we are rapidly changing the climate, we could cause extreme disruption within the near future for our entire society.

Bierman: If all the Greenland ice sheet melts, we're going to add about 7 meters, 23 to 24 feet, to sea level. And if you think about the cities you know that are within 20 feet of sea level, we can start in the U.S. and look at Boston and New York and New Orleans.

If you bring that back to Vermont, clearly, last time I checked, the only coastline we had was Lake Champlain and Lake Champlain is 100 feet above sea level. We are not going to be affected directly by that, but our country is going to be affected.

The fishing industry is going to be affected. Our defense, Newport News military base is going to be affected. And loss of the Greenland ice sheet itself triggers what’s called a feedback in climate.

So Greenland is one big white sheet right now, and almost all the sunlight that hits that Greenland ice sheet is reflected. When that ice sheet goes away, Greenland becomes a dark brown, gray, green continent that absorbs that sunlight. And so there's a positive feedback.

As we lose the Greenland ice sheet, the earth will get warmer. That will matter to Vermont. It will matter to our maple syrup. That will matter to our winters and our skiing and our industries. So it seems like Greenland is far away from Vermont, but in fact, what happens in Greenland affects us every day here.

A man in outdoor gear walks across a snowy landscape.
Credit University of Vermont, Courtesy
UVM geology professor Paul Bierman while doing fieldwork in Greenland.

Well, finally, I want to sort of switch gears and ask about something that's a bit closer to home. And that's the proposed elimination of the geology department at UVM, which the UVM administration says is necessary due to budget shortfalls. And I'm curious how you're each grappling with the potential for these cuts while you're also releasing these major and important findings from your research?

Bierman: That's a really difficult question. It has been an incredibly hard last three months, after spending 28 years at the University of Vermont. It’s the only place I've ever taught, that I've ever done research. I built a laboratory here. I've been just blessed to have an amazing group of graduate students and postdocs working with us here as a team.

We are trying really hard right now to find another home at the University of Vermont. And there's some really good discussions going on about that. I'll leave it to others to talk about the budget deficit or apparent budget deficit. That's not my expertise.

But what I do know is that geoscience is absolutely critical to the state of Vermont and that we are integral to training the environmental scientists of the future. That's a bad pun, but without the bedrock of geology, you can't train environmental scientists properly. They need to know the earth on which the plants grow and the water flows and the climate.

And I'm really happy that the work that that Drew did here and coordinated can aid to that. I mean, I think this is what we're capable of at the University of Vermont. We can be a national and international influence on how we think about the world and how we think about science.

Have questions, comments or tips? Send us a message or get in touch with reporter Henry Epp @TheHenryEpp.

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