A glacial toe caused by melting grows near Ilulissat, Greenland, on July 15, 2013. (Joe Raedle/Getty Images)

Editor’s note: In light of the news that President Trump is interested in purchasing Greenland, we asked Jeff Colgan to update his piece on toxic waste and climate change.

On Thursday, the Wall Street Journal reported that President Trump has repeatedly expressed interest in buying Greenland. Trump is reportedly interested in the territory’s national resources and usefulness to the U.S. military.

But there’s something lurking beneath Greenland’s icy surface that Trump may want to know about: toxic nuclear waste, left over from the Cold War, that may be exposed by climate change that is melting ice at a rapid rate.

What’s more, the United States may owe Denmark — the country Trump would presumably have to make a deal with to buy Greenland — money to pay for the environmental cleanup.

Here’s what’s going on.

Congress is concerned about nuclear waste and climate change

In May, Sen. Thomas R. Carper (Del.), the top Democrat on the Senate Environment and Public Works Committee, wrote to the head of the Government Accountability Office to request “a study on international sites that store or are contaminated by nuclear waste from United States activity.”

More specifically, Carper asked the GAO to “identify and address any risks these sites face from climate change.” Growing environmental concerns could further complicate the already contentious politics of military sites around the world — and Carper’s letter spotlights the growing clash between the nuclear age and the age of climate change.

What’s the upshot? That clash could end up costing the U.S. government millions of dollars, paid to overseas governments like Denmark as compensation for environmental damages.

Carper cited three such sites, including Camp Century, built in Greenland between 1953 and 1967. My research on Camp Century shows that climate change will eventually expose toxic waste, long immobilized by ice, which the U.S. military left in the 1960s. This situation — which has already spurred Greenland to lodge a formal complaint at the United Nations — could prove to be the canary in the coal mine, signaling yet another way that climate change damages our world and complicates politics.

Camp Century was home to Project Iceworm, a top-secret Army initiative that sought to deploy up to 600 medium-range ballistic missiles with nuclear warheads along a 2,500-mile-long railway cut into the Greenland ice sheet. Had it been completed as planned, it would have served as a secure second-strike capability against the Soviet Union. But Project Iceworm sites were abandoned with minimal decommissioning in the 1960s. The Army assumed that snowfall and low temperatures would entomb these sites in perpetuity.

Fast-forward to 2019, when rising temperatures mean Greenland’s ice sheet is now melting faster each year. If the polychlorinated biphenyls (PCBs), excess diesel fuel and radioactive wastewater from Camp Century are exposed, they will contaminate the region’s ecosystem.

This contamination potentially puts U.S. personnel at Greenland’s Thule Air Base at risk and might even cross national boundaries to Canadian territory. Although it will be decades before the contaminants are likely to be exposed, this looming hazard could spur diplomatic difficulties between the United States and Greenland in the present.

Camp Century is a case study for understanding the political fallout of the additional effects of climate change. These are secondary environmental problems — such as damage to infrastructure or the release of chemicals or waste housed on site — that can manifest when temperatures and sea levels rise. Chemical releases after Hurricane Harvey in 2017 were a good example of such knock-on effects.

How much nuclear waste will climate change expose?

The environmental effects of climate change will affect the politics of various military sites around the world — not just those in the Arctic. Cold War-era sites in the Pacific Ocean, including Johnston Atoll and the Marshall Islands’ Runit Island, also host radioactive leftovers.

U.N. Secretary General António Guterres recently toured some of those Pacific islands and highlighted some of the hidden dangers of climate change. Rising sea levels elevate the risk that toxic waste left on these low-lying coral islands could be released into the ocean.

None of this exactly helps the U.S. international reputation. And it’s not just Congress that is worried. A 2017 GAO report noted the U.S. military is not doing enough to address the problems that climate change is expected to cause at military bases.

How much will this cleanup cost?

Taxpayers might wonder who will foot the bill. The answer depends on the size of the costs and who pays for them. At Camp Century, for instance, neither the United States nor Denmark has yet taken responsibility for the cleanup costs. At the time the base was built, Greenland was a colony of Denmark — today it is a semi-sovereign nation.

Denmark is funding what little environmental monitoring there is of the site — though more monitoring and research are needed. One clause of a 1951 treaty agreement appears to allow the United States to leave waste at military bases in Greenland, but the treaty also contains significant caveats that could allow Denmark to compel the United States to share the costs.

A historical precedent that might inform thinking in the Congress is the Canadian experience decommissioning the Distant Early Warning system of radar stations in the Arctic, built and largely funded by the United States. In 1996, the United States agreed to pay Canada $100 million to partially defray the cost of cleaning up four decommissioned installations.

The environmental cleanup at Camp Century does not have an accurate price tag. Still, given its size, isolated location, technical complexity and the fact that it contains radioactive waste, cleaning up this site will probably cost considerably more than the remediation efforts at any of the individual radar stations in Canada. In the end though, Canada, not the United States, bore most of the overall cleanup costs.

Denmark has reason to be nervous. Given the huge U.S. network of overseas military bases, the Department of Defense has traditionally seen the issue of environmental liability as a slippery slope and takes a hard line against assuming responsibility. That might be good for the U.S. government’s finances — but would make a deal with Denmark to buy Greenland, never a likely prospect, that much tougher.

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Jeff D. Colgan (@JeffDColgan) is the Richard Holbrooke associate professor of political science at Brown University.