Erosion on the shores of the Ninglick River is seen on July 3, 2015 in Newtok, Alaska. Newtok is one of several remote Alaskan villages that is being forced to relocate due to warming temperatures which is causing the melting of permafrost, widening of rivers, and the erosion of land and coastline. | Andrew Burton/Getty Images

Melting Arctic Permafrost Could Release Millions of Gallons of Mercury Pollution

The tundra of Eurasia and North America contains twice as much mercury as the rest of the world combined.

This diagram shows the modern mercury cycle with major reservoirs in white (gigagrams of mercury) and exchanges between reservoirs in black (gigagrams of mercury per year). Northern Hemisphere permafrost contains 863 gigagrams of mercury in the active layer, the layer of ground that is subject to annual thawing and freezing. About 793 gigagrams of mercury is found in Northern Hemisphere permafrost. | Schuster et al./GRL/AGU
This image shows soil mercury content (in micrograms of mercury per square meter) in Northern Hemisphere permafrost zones for four soil layers: 0 to 30 centimeters, 0 to 100 centimeters, 0 to 300 centimeters, and permafrost. The permafrost map represents mercury bound to frozen organic matter below the active layer and above a depth of 300 centimeters. | Schuster et al./GRL/AGU