Melting permafrost and dissolving rocks

Photo credit: NOAA

More information revealed about climate change:

Scientists recently received a very unpleasant surprise while studying melting permafrost in the Arctic. They’ve known for years that global warming is releasing CO2, which has been long trapped in the ice, into the atmosphere; that greenhouse gas is helping to drive rapid climate change in the Great White North. However, recent studies have found that melting permafrost is also turning loose an acid that is causing rocks to dissolve over a relatively short time.

Scientists were alarmed by the permafrost melting before; this newly discovered dissolving rock phenomenon has increased the concern.

What kind of acid is doing this? The answer is sulphuric acid, which was found in the western Canadian Arctic permafrost that contained large amounts of mineral sulfides. According to a new study published in the journal Geophysical Research Letters, scientists have discovered surprisingly high levels of sulphuric acid in the air and streams of that region, now that the ice that used to cover the ground is gone. Researchers have also found that carbonic acid released from permafrost melt breaks down rocks, too, but at a much slower pace, and apparently without releasing CO2 .

Here’s how it works. Permafrost is ground that has been frozen at least two years, and often much longer. It contains a lot of minerals, which are released when it thaws. Once the thawing is done, the mineral-bearing rocks are then subject to a natural process called “chemical weathering”, in which the rocks are broken down by chemical reactions.

The chemical weathering itself is part of a larger process called “thermokarst”—a word coined by Russian scientists to describe large-scale land erosion that results from thawing permafrost, according to the U.S. Geological Survey.

Thermokarst has created sinkholes, pits, and even lakes. Prior to the Canadian Arctic study, it was unclear whether thermokarst affected the weathering of newly exposed minerals and how much CO2 they might release into the atmosphere. The scientists’ report says, “These processes may influence the permafrost carbon-climate feedback, but have received little attention.”

There is an estimated 1, 400 billion tons of carbon stored in permafrost around the world, according to the website Live Science. As climate change thawing continues around the world, so will the dissolution of sulfide-rich rocks and the release of their CO2. There is a chance that the release of carbonic acid from other minerals might balance out that CO2 increase. But, whether that will happen is anybody’s guess.

About the author

Dave Segal

Dave Segal

Dave Segal, a Detroit native, has been a journalist since 1977. He has worked as a reporter, commentator, and news director at radio stations in Detroit, Denver, and Montrose.

Dave has been writing and editing for the Monitor since its first print issue in 2003. He is editor and senior writer for the digital magazine. On the side, Dave has also done freelance writing, media relations, and a variety of volunteer work.