Dirt jars extracted from a Cold War-era military caper and lost in a freezer for decades could contain crucial new information about climate change and rising sea levels. A to study published Monday in Proceedings of the National Academy of Scientists says plant fossils found in a dirt sample collected a mile under ice in the mid-1960s suggest the world’s pre-human climate was at a time warm enough to melt -the Greenland ice sheet is completely gone.
The inspected dirt investigators are a sample of sediment from the bottom of an ice core, recovered by drilling into the ice sheet that covers most of Greenland. It’s pretty hard to get to the bedrock when samples are taken because of the incredible pressure of the ice, explained Drew Christ, lead author of the study and a postdoctoral fellow at the University of Vermont. There are only a few expeditions that have reached sediments from the bottom of the glacier. “It simply came to our notice then [sediment] than the rocks of the moon, ”said Christ.
This particular sample produced a lot of plant matter, some of which was visible to the naked eye. “It’s like you were going on hikes and you had a bunch of twigs and stuff from the forest floor at the bottom of the boot and you spilled them at the end of the day,” Christ said. “It’s a bit like that, but it’s been frozen for a million years.”
Christ and the team behind the study used isotope analyzes of various elements that helped the researchers remove the last time the samples were exposed to the sun and cosmic rays. Dates showed that plant matter is approximately one 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. But the discovery of these fossils definitely suggests that Greenland had been ice-free enough to provide a home for several plants. And that’s bad news for us right now. The Greenland ice sheet is a ticking climate bomb, with some estimates projecting that the layer could raise sea level by 6.1 meters. if it melted completely. While it is not expected to melt completely tomorrow, the ice sheet is already there melting six times faster than it was in the 1980s. The changes brought about by the rise in carbon dioxide will take centuries to occur as the climate adapts to a new equilibrium. Knowing its 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,” Christ explained. “Before humans added hundreds of parts per million fossil fuels to the atmosphere, our climate was able to melt the ice sheet. In the future, as we continue to warm the planet at an uncontrollable rate, we could force the Greenland ice sheet to cross a threshold and melt it and raise sea levels. ”
The dirt show that Christ and his team used to come to these conclusions has its own amazing story, including that it was almost lost for history. The sample was originally recovered from Greenland’s first ice core ever taken during a 1966 expedition to a military base called Camp Century. The real purpose of the expedition was a top-secret mission called the James Bond style Iceworm Project (Yes, really) to try to hide nuclear missiles under the ice near the Soviet Union (we are not inventing it). The scientific part of the expedition, while valid, was created primarily to cover this Cold War caper. The Iceworm project finally failed, but at least we pulled out this fascinating ice core. (But on the downside, climate change is wearing out from Camp Century and could cause a spill of toxic waste supplies and chemicals from the Cold War era)
While the dirt sample is remarkable, as the Camp Century attempt was the first ice core to be recovered from Greenland, the researchers were primarily interested in what the ice itself could tell them and invested less. in the dirt that accompanied the core.
“He was pulling out branches an inch long from this material. We could see with our naked eyes, as if it were definitely plant material,” Christ said. “Looking at this as someone who was born long after all this. fell, it’s like, like it was [the scientists] don’t you think you look more closely? I think they had more priority to analyze the ice and then the soil was not analyzed.
In what Christ describes as a “strange trick of history,” the ground was such a low priority for researchers that it was finally lost when the expedition arrived home. The samples were placed in the back of an army freezer at the University at Buffalo, and then moved incognito with a pile of other materials to another freezer at a research center in Denmark at nineties. It was only in 2017, as JP Steffensen, one of Christ’s mentors and author of the document, was making an inventory helping that facility prepare its freezer for a move, the samples were rediscovered and analyzed. more completely.
And while researchers in the 1960s may not have known what they achieved when they unearthed ancient dirt, Christ is grateful that his work provided him with one of the most 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 to scientists, but it did to me,” he said, describing how he first saw material. vegetable while his team cleaned the sediment samples for analysis. “I was jumping in the lab. It was so exciting.”