Potentially toxic wastes left over from a former U.S. army base in Greenland could re-enter the environment and potentially disrupt ecosystems if ice melt begins in the northwest of the island where the camp is located, according to a study published in Geophysical Research Letters, a journal of the American Geophysical Union.

Camp Century, a U.S. military base built within the Greenland ice sheet in 1959, doubled as a site for testing the feasibility of deploying nuclear missiles from the Arctic during the Cold War. When the camp was decommissioned in 1967, its infrastructure and waste were abandoned under the assumption that they would be entombed forever by perpetual snowfall. But climate change has warmed the Arctic more than any other region on Earth, and the study finds the portion of the ice sheet covering the camp could start to melt by the end of the century.

Known as the "city under the ice," Camp Century’s purpose was to test construction techniques in the Arctic and conduct scientific research. While in operation, it housed 85-200 soldiers and was powered by a nuclear reactor.

A thermal coring rig used to take ice cores at Camp Century in 1964. Image credit: U.S. Army. Several years after the camp became operational, the missile launch program, known as Project Iceworm, was rejected by the Joint Chiefs of Staff and the camp was decommissioned. The Army Corps of Engineers removed the nuclear reaction chamber but left the camp’s infrastructure and other waste behind. In the decades since, snow has buried the camp roughly 35 meters deeper beneath the ice.

In the new study, a team led by William Colgan, a climate and glacier scientist at York University in Toronto, inventoried the wastes at Camp Century and ran climate model simulations to determine whether they are likely to stay put in a warming Arctic. They analyzed historical U.S. Army engineering documents to determine where and how deep the wastes are buried and how much the ice cap had moved since the 1950s. Ground-penetrating radar from NASA’s Operation IceBridge aircraft was used to pinpoint the camp’s location and depth.

“The radar shows smooth layers of snow and ice until reaching the camp," says Mike MacFerrin, a researcher at the Cooperative Institute for Research in Environmental Sciences and co-author of the paper. "Then the signal gets messy. We don’t yet have enough detail to map exactly what all is down there, but the outline is clear.”

The team found the waste at Camp Century covers 55 hectares. They estimate the site contains 200,000 liters of diesel fuel. Based on building materials used in the Arctic at the time, the authors also speculate the site contains polychlorinated biphenyls, which are chemicals toxic to human health. They further estimate the site has 240,000 liters of waste water, including sewage, along with radioactive coolant from the nuclear generator.

Looking at existing business-as-usual climate projections, the team determined the wastes would not remain encased in ice forever, as was assumed by both the U.S. and Denmark when the camp was abandoned.

“When we looked at the climate simulations, they suggested that rather than perpetual snowfall, it seems that as early as 2090 the site could transition from net snowfall to net melt,” Colgan says. When the ice melts, pollutants could be transported to the ocean, where they could disrupt marine ecosystems.

The study does not advocate beginning remediation activities at Camp Century now. The waste is buried tens of meters below the ice, and any cleanup activities would be costly and technically challenging, according to Colgan.

“It really becomes a situation of waiting until the ice sheet has melted down to almost expose the wastes that anyone should advocate for site remediation,” he says.