This past spring, a fuel tank at a power plant in northern Russia collapsed. The massive tank was the size of a four-story building—and when it broke, it released about 2 million liters (528,000 gallons) of diesel fuel. The toxic and highly flammable chemical contaminated the nearby Ambarnaya River, turning its water blood red.

The spill occurred within the Arctic Circle. Usually the ground in that region contains a layer of soil that remains frozen year-round. But rising temperatures linked to climate change are causing this permafrost to melt. Experts believe that’s what caused the fuel tank to topple.

“Everything in the Arctic is built on frozen ground,” says Victoria Herrmann, director of the Arctic Institute in Washington, D.C. “When the permafrost melts, nothing is safe.” It could take decades for the environment to recover from the spill.