Environment

A Ticking Time Bomb of Mercury Is Hidden Beneath Earth's Permafrost

According to a new study published Feb. 5 in the journal Geophysical Research Letters, theremay be more than 15 million gallons (58 million liters) of mercury buried in the permafrost of the Northern Hemisphere — roughly twice as much mercury as can be found in the rest of Earth's soils, ocean and atmosphere combined. And if global temperatures continue to rise, all that mercury could come pouring out.

In geology, permafrost is defined as any soil that has been frozen for more than two years. In the Northern Hemisphere, permafrost accounts for about 8.8 million square miles (22.79 million square kilometers) of land — or roughly 24 percent of exposed Earth, according to the National Snow and Ice Data Center. Over time, naturally occurring compounds in the atmosphere, such as mercury and carbon dioxide, can bind with organic material in the soil and be frozen into permafrost, potentially remaining trapped underground for thousands of years before it thaws.

Using the mercury contents of 13 cores drilled in various sites across the North American permafrost as a springboard, the researchers estimated the total amount of mercury sealed away below North American permafrost to be roughly 793 gigagrams — or more than 15 million gallons.