Arctic Permafrost is Leaking Acid and Dissolving the Rocks Beneath

The permafrost in the Arctic is leaking acid as it thaws, scientists have discovered.

This release, from the water that has been locked up for thousands of years, is causing rocks in the ground to dissolve—a process that could become a major source of atmospheric carbon dioxide.

In a study published in the journal Geophysical Research Letters, scientists at the University of Alberta, Canada, looked at how much CO2 was being released from mineral weathering.

This is where minerals locked up in the permafrost—ground that has been frozen for potentially thousands of years—are released and broken down into their chemical components by the sulfuric and carbonaic acid that can exist in water.

Permafrost across the arctic is starting to thaw as global temperatures increase. As it thaws, organic matter that had been frozen starts to break down and carbon dioxide and methane (a potent greenhouse gas) are released. This is of concern to climate scientists as it has the potential to create a positive feedback loop. As the ground thaws and releases greenhouse gasses, it contributes to warming and therefore more thawing.

Understanding how much carbon dioxide is being released and through which processes is important for our climate models showing future warming.

"We found that rapidly thawing permafrost on the Peel Plateau in the Northwest Territories is greatly enhancing mineral weathering," lead author Scott Zolkos said in a statement. "Because weathering is largely driven by sulfuric acid in this region, intensifying permafrost thaw could be an additional source of CO2 to the atmosphere."

The team studied part of the Canadian Arctic. They discovered weathering from sulfuric acid has become more intense over recent decades—in line with regional permafrost thaw. They say this probably increased the amount of CO2 being released.

"Any additional warming in the Arctic, which is warming at twice the rate of the rest of the planet, promotes more permafrost thaw and thus poses substantial challenges to Arctic and global ecosystems," Zolkos said, adding more research will be needed to understand what impact mineral weathering will have on the climate.

"Across the Arctic, increasing thermokarst will profoundly impact freshwater carbon cycling, yet the influence of weathering on climate feedbacks will depend on regional variation in the mineral composition of permafrost soils," the scientists conclude.

Scientists are currently paying close attention to the thawing permafrost across the arctic. While we know methane and carbon dioxide is being released, just how much is not clear. Recently, a NASA funded study revealed Arctic lakes bubbling with methane. This source of CO2, from "thermokarst" lakes, has not been accounted for in climate models.

It is currently estimated there is around 1,500 billion tons of carbon locked up in the permafrost. That is nearly double the amount of carbon in the atmosphere right now.