Climate change could release toxic mercury
As Arctic permafrost melts, greenhouse gases threaten health
We already knew that thawing Arctic permafrost would release powerful greenhouse gases. On Monday, scientists revealed it could also release massive amounts of mercury — a potent neurotoxin and serious threat to human health.
Permafrost, the Arctic’s frozen soil, acts as a massive ice trap that keeps carbon stuck in the ground and out of the atmosphere — where, if released as carbon dioxide, the greenhouse gas would drive global warming.
That cycle would be scary enough, but U.S. government scientists on Monday revealed that the permafrost also contains large volumes of mercury, a toxic element humans have already been pumping into the air by burning coal.
There are 32 million gallons worth of mercury, or the equivalent of 50 Olympic swimming pools, trapped in the permafrost, the scientists wrote in a study published in the journal Geophysical
Research Letters. For context, that’s “twice as much mercury as the rest of all soils, the atmosphere, and ocean combined,” they wrote.
“As permafrost thaws in the future, some portion of this mercury will get released into the environment, with unknown impact to people and our food supplies,” said Kevin Schaefer, a scientist with the National Snow and Ice Data Center in Boulder, Colo., and a co-author of the study. The research was led by Paul Schuster, a scientist with the U.S. Geological Survey, and was co-authored by 16 other federal, university-based and independent researchers.
Mercury, a naturally occurring element, binds with living matter across the planet — but the Arctic is special. Normally, as plants die and decay, they decompose and mercury is released back to the atmosphere. But in the Arctic, plants often do not fully decompose. Instead, their roots are frozen and then become buried by layers of soil. This suspends mercury within the plants, where it can be remobilized again if permafrost thaws.
How much would be released depends on how much the permafrost thaws.
The question then becomes where this mercury will go, and what it will do — and the scientists say they aren’t sure of that. It could flush out through rivers into the Arctic Ocean. Or it could enter the atmosphere. Or both. That remains to be determined.
Sue Natali, a permafrost expert at the Massachusetts-based Woods Hole Research Center who was not involved in the study, said in a statement: “The results of this study are concerning because what we’re learning is that not only is permafrost a massive storage for carbon that will feedback on global climate, but permafrost also stores a globally significant pool of mercury, which is at risk of being released into the environment when permafrost thaws. But the magnitude of this risk is as yet unknown,” Natali said.