It sounds like something out of a James Bond movie: a secret military operation hidden beneath the Greenland Ice Sheet. But that’s exactly what transpired at Camp Century during the Cold War.

In 1959, the U.S. Army Corps of Engineers built the subterranean city under the guise of conducting polar research—and scientists there did drill the first ice core ever used to study climate. But deep inside the frozen tunnels, the corps also explored the feasibility of Project Iceworm, a plan to store and launch hundreds of ballistic missiles from inside the ice.

The military ultimately rejected the project, and the corps abandoned Camp Century in 1967. Engineers anticipated that the ice—already a dozen meters thick—would continue to accumulate in northwestern Greenland, permanently entombing what they left behind.

Now, climate change has upended that assumption. New research suggests that as early as 2090, rates of ice loss at the site could exceed gains from new snowfall. And within a century after that, melting could begin to release waste stored at the camp, including sewage, diesel fuel, persistent organic pollutants like PCBs, and radiological waste from the camp’s nuclear generator, which was removed during decommissioning.

If these predictions come to pass, the researchers say the cleanup could create political tension between the United States and Denmark, which granted Greenland partial autonomy in 1979. The situation would also represent a new type of climate dispute, one that offers a glimpse of the kinds of multigenerational and multinational challenges society can expect to encounter, says Liam Colgan, a glaciologist at York University in Toronto, Canada, and lead author of the study, published today in Geophysical Research Letters .

Colgan’s team used two different combinations of regional and global climate models to estimate how conditions might change at the camp’s location in the future. They considered an emission scenario in which temperatures rise 5°C by 2100. One model pair predicted that Camp Century would begin to lose ice around 2090; another suggested it could remain safe into the next century. But, Colgan says, “we would just say it’s going to take longer in that scenario.”

Whenever the ice does start to disappear, the researchers estimate it will take another 90 years or so for surface melting to eat through the estimated 60 meters of ice that will cover the camp by then. But meltwater percolating down through the ice sheet could pick up and wash abandoned waste downstream decades sooner.

PCBs may pose the largest danger to the environment and human health, Colgan says, and they could be abundant at Camp Century, although it’s hard to know for sure. The military used paints containing up to 5% PCBs at other Arctic sites built around the same time—including the Distant Early Warning (DEW) Line radar sites that scanned for Soviet missiles coming over the pole. U.S. and Canadian authorities have already remediated much of this pollution at DEW Line stations in North America.

Camp Century also contains radiological waste, although the amount pales in comparison to the contamination unleashed by the nearby crash of a U.S. B-52 bomber in 1968. That plane was loaded with four hydrogen bombs when it went down on the sea ice near the Thule Air Base—200 kilometers west of Camp Century—releasing radioactive elements including uranium and plutonium. The United States and Denmark quickly launched project Crested Ice to contain and recover the pollution, although studies have found that some persists today.

Without any established agreement on who now bears the responsibility for cleaning up Camp Century, Colgan and his colleagues argue that the situation could strain relationships between the United States, Greenland, and Denmark. Denmark originally granted the United States permission to establish military bases there, although it’s unclear whether the Danish government knew about the full scope of activities at Camp Century. Representatives of the Danish and Greenlandic governments, and U.S. military officials, did not respond to requests for comment.

“It plays into a discussion about the U.S. and Denmark using Greenland for their own purposes, and then the Greenlandic people have to deal with it afterwards,” says Kristian Nielsen, a science historian at Aarhus University in Denmark, who was not involved in the study. Even before the construction of Camp Century and the plane crash, military operations had impacts on Greenlanders: The entire Inuit village of Uummannaq was relocated in 1953 to make way for the construction of the Thule Air Base, about 240 kilometers west of Camp Century.

Aqqaluk Lynge, a board member and former president of the Inuit Circumpolar Council of Greenland in Nuuk, helped secure modest reparations from Denmark for the displaced residents of Uummannaq, and he says waste leaching from Camp Century would certainly be a problem. If it reaches the ocean, he says, it could impact the North Water Polynya, an ice-free area off the island’s northwest coast that provides important year-round habitat for marine mammals and birds. However, Lynge says that Greenland has maintained a good relationship with the United States, and he is optimistic that Greenlandic officials and their Danish counterparts will find a way to collectively address the problem if and when it arises. “It will be a new situation that we have to find a common ground on,” he says.

Colgan argues that a good first step would be to conduct more research on how climate change could affect the ice sheet and its buried hazards. But he says Denmark and North Atlantic Treaty Organization research programs both declined to support his work, despite the fact that his proposals each received favorable technical reviews. “Both rejections were fairly explicit that it was basically a touchy science topic,” says Colgan, who, along with his colleagues, completed the research in his spare time.

Colgan and his co-authors aren’t arguing for remediating the waste at Camp Century anytime soon—a prohibitively expensive proposition. It would only become necessary after ice melt has progressed substantially, and that may not happen as soon as the study suggests, says Ian Howat, a glaciologist at The Ohio State University, Columbus, who was not involved in the study. The new results hinge on greenhouse gas emissions increasing at an unabated pace, “which I hope is not a reasonable presumption,” Howat wrote in an email.

However, it’s important to consider the worst-case scenario, says Miren Vizcaíno, a climatologist at the Delft University of Technology in the Netherlands. “It is very good that we have the knowledge of what would happen if we don’t do anything.” Some of her previous work suggests that Camp Century could remain in the accumulation zone until at least 2100, because increasing snowfall—another consequence of climate change—may offset melting there. But that could just be temporary: The spot may eventually succumb to ice loss if warming continues, she says.

The possibility, however remote, illustrates the kinds of unexpected political conflicts that will begin to arise in a warming world, Colgan says. Sooner or later, he says, “the international community needs to develop mechanisms to deal with these sorts of thorny climate change issues.”