Fossils in a forgotten ice core rewrite Greenland’s icy past


The secret military plan never happened – engineers quickly learned how fast and unpredictably the ice could move, making the site extremely unstable and completely unsuitable for nuclear weapons. Colgan, the project manager of Climate monitoring program at Camp Century, was among the few who made it to the site of the former army installation, now buried under more than 100 feet of accumulated snow and ice. “The tunnels are collapsed and compressed,” he says. “The snow turned to ice with pancakes of debris.”

Camp Century was abandoned in 1967, just a year after its engineers achieved a veritable scientific feat: drilling the first ice cores. Along with more recent cores from Antarctica and elsewhere in Greenland, these thin cylinders of ice provide a crucial record of ancient climatic conditions that researchers have since used both to understand our past and to model our future. Colgan says Camp Century has been invaluable to science now more than ever.

“Camp Century was the first ice core program, and we’re still learning from it,” Colgan says, adding that the Cold War-era team likely realized the site’s inadequacy as a missile base. very early in their work, but persevered in the name of science. The subglacial sample, he says, “only exists because they wouldn’t take no for an answer. They slammed all the way into the bedrock and even kept moving forward.

A portion of the mile-long Camp Century ice core had already been surveyed. After being collected in 1966, however, the subglacial core sample – about 12 feet of frozen mud and bedrock under the ice – was stored in an army lab freezer, then at the University. from Buffalo. The sample was eventually sent to Denmark, where it languishes once again, in the University of Copenhagen ice core archives.

In 2017, as staff prepared to upgrade the facility, someone noticed unopened boxes of Camp Century carrot samples. Inside, rather than the thin cylinders typical of ice cores, they found glass jars of subglacial rock and clumps of frozen sediment. Almost immediately, the discovery became a sensation on the pitch. Obtaining a comparable subglacial sample today using modern drilling technology would have been prohibitively expensive.

“We knew how important these samples would be. We all started to shake and even drool a little, ”Schaefer says. As word of the samples spread, he flew to Copenhagen with University of Vermont geologist Paul Bierman in hopes of negotiating some of the material. “We were trying not to let them see how excited we were. We just tried to keep it together.

Subglacial material, collected from where the borehole reached the sediment and bedrock below the ice cap, contains information that the ice does not contain. Exposed rock, like everything on the Earth’s surface, is bombarded with cosmic rays, producing chemical signatures, called cosmogenic nuclides, which can be used to determine if, and when, an area was ice-free. “Nuclides are only produced if the rock sees the open sky,” says Schaefer. The job of dating the material is “really, really hard,” Colgan says, but the Camp Century sample was initially dated, with certainty, to be less than a million years old, aligned with the sample. previously studied from central Greenland.

Christ, Schaefer and their colleagues continue to analyze the material at Camp Century to narrow down its age range and learn more about the plant material it has preserved, which is unique, as massive ice deposits typically destroy the organic material. The next phase of research, already underway, includes looking for traces of DNA that could be used to determine the species present, or even reconstruct the entire ecosystem. So far, it looks similar to the modern arctic tundra.

There is still more to explore in the heart of Camp Century. The lower layers of the sample include sediment that may be up to 3 million years old, Christ says, and may include more organic material that may be “the oldest material ever recovered from under ice.”

Camp Century may never have hosted nuclear weapons, but it turns out to be far more important than even its planners imagined.


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