Jars of dirt from a Cold War military barber and decades lost in a freezer may contain crucial new information about climate change and sea level rise. A study published Monday in Proceedings of the National Academy of Scientists says plant fossils found in a sample of debris collected from a mile below the ice in the mid-1960s suggest the world’s prehuman climate was once warm enough to melt completely the Greenland ice sheet.
The dirt researchers inspected are a sediment sample from the bottom of an ice core, recovered by drilling in the ice sheet that covers most of Greenland. It’s pretty hard to really reach all the way to the bottom when taking samples because of the incredible pressure of the ice, explained Drew Christ, the study’s lead author and a postdoctoral fellow at the University of Vermont. Only a few expeditions have actually gotten sediment from the bottom of the glacier. “We have less of this [sediment] than moonstones, ”said Christ.
This particular sample yielded a lot of plant material, some of which was visible to the naked eye. “It’s like going for a walk and getting a bunch of twigs and forest stuff in the bottom of your boot and pouring it out at the end of the day,” said Christ. “It’s like that, but it’s been frozen for 1 million years.”
Christ and the team behind the study used isotope analyzes of various elements that helped the researchers tease the last time the samples were exposed to the sun and cosmic rays. The dating showed that the plant matter is about 1 million years old.
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Before analyzing this particular sample, Christ said, scientists had “circumstantial” evidence that the Greenland ice sheet had once completely melted away. But the discovery of these fossils definitively suggests that Greenland was once ice-free enough to provide a home to a variety of plants. And that’s bad news for us right now. The Greenland Ice Sheet is a ticking climate bomb, and according to some estimates, sea levels could rise by 6.1 meters. when it has completely meltedWhile it is not intended to melt completely tomorrow, the ice sheet is now melts six times faster than in the eighties. It will take centuries for the changes triggered by rising carbon dioxide to materialize as the climate adjusts to a new equilibrium. Knowing the history is crucial to understanding the future of the ice sheet.
“The Greenland ice sheet has disappeared in a climate system that had no human influence whatsoever,” Christ explained. “Before humans added hundreds of parts per million of fossil fuels to the atmosphere, our climate was able to melt away the ice sheet. In the future, as we continue to heat the planet at an uncontrollable rate, we could force the Greenland ice sheet over a certain threshold and melt it and raise sea levels. “
The dirt monster that Christ and his team used to come to these conclusions has its own incredible backstory, including that it was almost lost in history. The sample was originally recovered from Greenland’s first ice core ever taken on an expedition in 1966 to a military base called Camp Century. The actual purpose of the expedition was called a top secret James Bond-style mission Project ice worm (yes, really) to try to hide nuclear missiles under the ice near the Soviet Union (we’re not making this up). The scientific part of the expedition, while valid, was created primarily to provide cover for this Cold War hairdresser. Project Iceworm ultimately failed, but at least we got this fascinating ice core out of here. (On the other hand, climate change is melting Camp Century, and it could be cause toxic waste spillage of leftover supplies and chemicals from the Cold War.)
While the dirt monster in itself is remarkable, since the Camp Century attempt was the first ice core ever extracted from Greenland, researchers were particularly interested in what the ice itself could tell them, investing less in the dirt that left the core. came.
‘I pulled inch-long twigs out of this stuff. We could see with our naked eyes, this is definitely vegetable matter, ”said Christ. Seeing this as someone who was born long after this happened is like, how [the scientists] not think to look more carefully? I think they had more priority in analyzing the ice and then the bottom was not analyzed. “
In what Christ describes as a “ weird trick of history, ” the ground was such a low priority for researchers that it was eventually lost when the expedition got home. The samples were shoved into the back of a University at Buffalo military freezer and then moved incognito with a heap of other material to another freezer at a research facility in Denmark in the 1990s. It wasn’t until 2017, when JP Steffensen, one of Christ’s mentors and an author on the paper, took stock to help that facility prepare the freezer for a move, the samples were rediscovered and could be more fully analyzed.
And while researchers in the 1960s may not have known what they got when they dug up old garbage, Christ is grateful that their work brought him one of the more exciting moments of his scientific career.
“The day we found the fossils was one of those ‘eureka’ moments. I never thought those days would really happen for scientists, but it did for me, ”he said, describing how he first saw specks of plant material while his team cleaned the sediment samples for analysis. ‘I was hopping around the lab. It was so exciting. “