Fossils in a Forgotten Ice Core Rewrite Greenland’s Icy Past

The secret military plan never happened—engineers quickly learned how rapidly and unpredictably the ice can shift, making the site highly unstable and wholly unsuitable for nuclear weapons. Colgan, the project manager for the Camp Century Climate Monitoring Program, is one of a handful of people who have been 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 has turned to ice with pancakes of debris.”

Camp Century was abandoned in 1967, just a year after its engineers managed a true scientific feat: drilling the first ice cores. Together with more recent cores from Antarctica and elsewhere in Greenland, these slim cylinders of ice provide a crucial record of ancient climate conditions that researchers have since used both to understand our past and model our future. Colgan says Camp Century has been invaluable for 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 probably realized the site’s unsuitability 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 punched all the way into the bedrock and even then kept going.”

Some of the mile-long Camp Century ice core had been previously studied. After being collected in 1966, however, the subglacial core sample—about 12 feet of frozen mud and bedrock from below the ice—was stored in an Army lab freezer, then at the University of Buffalo. The sample was eventually sent to Denmark, where it languished yet again, at the University of Copenhagen’s ice core archive.

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

“We knew how important these samples would be. All of us started shaking and even drooling a bit,” says Schaefer. As word of the samples spread, he flew to Copenhagen with University of Vermont geologist Paul Bierman in hopes of negotiating for 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 drill hit sediment and bedrock below the ice sheet, contains information the ice does not. Exposed rock, like everything else on Earth’s surface, gets bombarded with cosmic rays, producing chemical signatures, called cosmogenic nuclides, that can be used to establish whether, and when, an area was ice-free. “The nuclides are only produced if the rock sees open sky,” Schaefer says. The work of dating the material is “really, really hard,” says Colgan, but the Camp Century sample has been initially dated, with confidence, as less than a million years old, lining up with the previously studied sample from central Greenland.

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

There’s yet more to the Camp Century core to explore. The very bottom layers of the sample include sediment that may be up to 3 million years old, Christ says, and may include more organic matter that could be “the oldest material ever recovered from under the ice.”

Camp Century may never have hosted nuclear weapons, but it is proving to be far more significant than even its planners imagined.


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