Acidic Runoff Released As Arctic Permafrost Melts Is Releasing CO2 From The Rocks It Dissolves

As temperatures rise in the Arctic, permafrost — permanently frozen ground — is defrosting at an alarming rate. But the permafrost isn't the only thing in the Arctic that's melting. Exposed rock that was once covered in ice is dissolving, eaten away by acid. And the effects of this acid bath could have far-reaching impacts on global climate, according to a new study.

Icy permafrost is rich in minerals, which are released when the ice melts. The minerals then become vulnerable to chemical weathering, or the breakdown of rock through chemical reactions, scientists recently reported. They investigated areas once covered by permafrost in the western Canadian Arctic, finding evidence of weathering caused by sulfuric acid, produced by sulfide minerals that were released when the permafrost melted. [See Stunning Photos of Earth's Vanishing Ice]

Another type of naturally occurring chemical erosion is caused by carbonic acid, and it also dissolves Arctic rock. But although carbonic-acid weathering locks carbon dioxide (CO2) in place, sulfuric-acid erosion releases CO2 into the atmosphere, and it does so in quantities that were not previously accounted for, researchers wrote in the study.

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Over geologic timescales, weathering caused by carbonic acid can help to regulate climate, by trapping CO2 and restricting its transfer into the atmosphere. But the researchers found that thermokarst in regions that were rich in sulfides drove production of sulfuric acid, rather than carbonic acid, and thereby released quantities of CO2.

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https://www.livescience.com/63612-arctic-acid-permafrost.html