Dirt jars taken from a Cold War military hijacker and lost in a freezer for decades may contain important new information about climate change and sea levels. A study Published Monday in Proceedings of the National Academy of Scientists says that plant fossils collected in a sample of dirt a mile under the ice in the mid-1960s indicate that the world’s pre-human climate is warm at some point was enough to completely melt the Greenland ice sheet.
The inspected dirt researchers are a sediment sample from the bottom of an ice core that is detected by the drilling layer in the ice sheet that covers most of Greenland. It’s pretty hard to actually get to the rock system when you take 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. There are only a few expeditions that have received sediment from the bottom of the glacier. ‘We have less of this [sediment] as moon rocks, ”Christ said.
This particular sample yielded a lot of plant material, some of which was visible to the naked eye. “It’s as if you went for a walk and found a bunch of twigs and forest flooring in the bottom of your shoe and threw it out at the end of the day,” Christ said. “It is so, but it has been frozen for 1 million years.”
Christ and the team behind the study used isotope analyzes of various elements that helped the researchers expose the samples to the sun and cosmic rays for the last time. The dating has shown that the plant material is about 1 million years old.
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Before Christ analyzed this particular sample, scientists had ‘circumstantial evidence’ that the Greenland ice sheet had once completely melted away. But the discovery of these fossils definitely indicates that Greenland was once ice-free enough to house 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, the sheet could raise sea level by 6.1 meters. if it melted completely. Although it will not melt completely tomorrow, the ice sheet is now melts six times faster than it was in the 1980s. The changes triggered by rising carbon dioxide will take centuries to play out as the climate adjusts to a new equilibrium. Knowing its history is crucial to understanding the future of the ice sheet.
“The Greenland ice 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 could melt the ice sheet. In the future, if we heat the planet at an uncontrollable pace, we could force the Greenland ice beyond a threshold and cause it to melt and raise sea levels. ‘
The dirt monster that Christ and his team used to come to these conclusions has its own incredible history, including that it was almost lost to history. The sample was originally recovered from the first ice core of Greenland ever taken during a 1966 expedition to a military base called Camp Century. The real purpose of the expedition was a top secret James Bond-like style mission Project Iceworm (yes, really) to try to hide nuclear missiles under the ice near the Soviet Union (we do not make it up). The scientific part of the expedition, though valid, was mostly created to cover these hijacking years. Project Iceworm eventually failed, but at least we got this fascinating ice core out of it. (But the downside is that climate change is causing Camp Century to melt away, and it could causes a spill of toxic waste of the remaining supplies and chemicals from the Cold War.)
Although the dirt sample itself is remarkable, the researchers were mostly interested in what the ice itself could tell them, and invested less in the dirt that contained the core.
‘I took thumb-long twigs out of this stuff. We could see with the naked eye, it is definitely plant material, ”Christ said. ‘If we consider it someone who was born after one of these things fell into disrepair, it’s like how it happened [the scientists] do not think to 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 eventually got lost when the expedition returned home. The samples were pushed into the back of an army freezer at the University of Buffalo and then moved incognito with a bunch of other material to another freezer at a research facility in Denmark in the 1990s. It was only in 2017, while JP Steffensen, one of Christ’s mentors and a writer on the page, was working on the inventory to prepare the freezer for a move, that the samples were rediscovered and more fully analyzed. .
And while researchers in the 1960s may not have known what they were getting when they dug up old dirt, Christ is thankful that they 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 scientists were really happening in those days, but it did happen to me, ‘he said, describing how he first saw plant material while his team cleaned up the sediment samples for analysis. ‘I jumped around in the lab. It was so exciting. ”