Arctic Warming Threatens to Set Off Toxic 'Mercury Bomb,' Study Warns

A study published Thursday in Environmental Research Letters warns that Arctic warming could unleash toxic mercury currently contained in rapidly thawing permafrost, potentially threatening the region's food supply and water quality.

Researchers from the University of Southern California's Dornsife College of Letters, Arts, and Sciences noted in the new study that the Arctic is "warming four times faster than the global average, destabilizing permafrost soils that have remained frozen for two or more years and that underlie much of the Arctic."

Mercury (Hg) deposits in the region's permafrost have "accumulated over thousands of years," the study authors noted, "and Hg in the top meter of Arctic soils potentially exceeds the total amount stored in the atmosphere, ocean, and all other soils."

Josh West, professor of Earth sciences and environmental studies at USC Dornsife and a study co-author, said in a statement that "there could be this giant mercury bomb in the Arctic waiting to explode."

The study notes that "a range of processes" can release mercury from permafrost, including riverbank erosion.

"The rivers are reburying a considerable amount of the mercury," West said. "To really get a handle on how much of a threat the mercury poses, we have to understand both the erosion and reburial processes."

Isabel Smith, a doctoral candidate at USC Dornsife and another study co-author, warned that "decades of exposure" to the toxic element, "especially with increasing levels as more mercury is released, could take a huge toll on the environment and the health of those living in these areas."

The study was published as parts of the Arctic experienced what The Washington Post's Ian Livingston described as "exceptionally high temperatures—up 30 to 40 degrees above normal."

"And it's happening as the National Oceanic and Atmospheric Administration just announced July was the 14th successive month with record-high global temperatures," Livingston wrote earlier this week. "Over the past week, temperatures soared to nearly 100 degrees Fahrenheit in Norman Wells, Canada, just 90 miles south of the Arctic Circle. Locations in Alaska set numerous record highs."

"Off the coast of Greenland, Longyearbyen, Norway, the northernmost city on Earth with a sizable population, witnessed its warmest August day, with a high of nearly 70," he added.