Because of that work, he’s been a guest on Science Friday, interviewed by a reporter from The Washington Post, and queried by other outlets. Christ is a postdoctoral fellow at the University of Vermont’s Gund Institute for Environment & Rubenstein School of Environmental and Natural Resources.
In 2019, five days away from defending his doctorate, he was working with his postdoc advisor, University of Vermont Professor Paul Bierman, on their ongoing analysis of the core samples from Greenland. Christ expected to find nothing but sand, but instead discovered perfectly preserved plant fossils from tundra.
The researchers later determined the fossils were from tundra that grew in Greenland at a time when the climate was not much warmer than it is today, when the island today is covered by an ice sheet. The plant fossils suggest that Greenland’s ice had melted and reformed at least once over the past million years, Christ and his co-authors wrote in an article published March 2021 in Proceedings of the National Academy of Sciences. Understanding Greenland’s ice sheet history is critical for predicting its response to future climate warming and contribution to related sea-level rise, they noted.
“That information is important for us to know now and looking towards the future, because it tells us about how sensitive Greenland is to temperature rise. What are the limitations to rises in temperature that we can subject the ice to before it melts away and raises sea level?” Christ asked. Such a melt would have catastrophic consequences, he said.
Their findings grabbed attention, and so did the backstory of the sediment cores. The U.S. army drilled the samples at the height of the Cold War as part of a mission on Arctic survival, Christ said. The army tunneled into the ice to create a base it dubbed Camp Century. Christ has heard a theory that the army wanted to determine if it could store nuclear weapons inside the ice sheet to hide them from the Soviets.
The core samples from the 1960s eventually were forgotten, stored in a freezer in Denmark until Danish scientists came upon them during a move to a new facility. One of the scientists asked Bierman if he was interested in working with them, and he convinced Christ to get involved.
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On behalf of a collaboration studying the samples, last summer Christ and his colleagues wrote a grant to the National Science Foundation (the first NSF grant he’d written) and received a $1.2 million shared award that will keep the work going for a couple of years. Christ, who discovered his love of environmental geology and polar climates at Hamilton, has much he wants to learn from the samples. One of the first tasks, he said, will be to analyze the ice in the sediment to learn about past changes in precipitation and temperature in that part of Greenland.
“And then we can look at the different plant fossils and maybe other types of fossils that we find in the sediment,” he said. “And a really cool thing that we hope to do is look at some ancient DNA in the sediment, which would tell us about everything that was living there. And that has not been done very often.”