Mineral weathering from thawing permafrost can release substantial CO2

Mineral weathering occurs when minerals previously locked-up in permafrost are exposed, and broken down into their chemical components by the sulfuric or carbonic acid that can exist naturally in water. Over long, geologic time scales, carbonic acid weathering is an important control on atmospheric CO₂ levels and climate. Under the right conditions, however, weathering by sulfuric acid can release substantial CO₂. Now, researchers from the Department of Biological Sciences have shown that these conditions are prevalent in the western Canadian Arctic, and are being enhanced by permafrost thaw.

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

To understand regional impacts of permafrost thaw and weathering, Zolkos and his supervisor Suzanne Tank, assistant professor of biology, worked with scientists from the Northwest Territories Geoscience Office to examine long-term records of river chemistry from the Peel River. Their results reveal that sulfuric-acid driven weathering has intensified with regional permafrost thaw in recent decades, and likely increased CO₂ release into surrounding water and air.

"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," explained Zolkos. Yet, the effects from this mineral weathering on climate warming remain largely unexplored -- a problem that Zolkos and Tank hope to address.

"We'd like to thank the local Northern residents involved in our work," added Zolkos, of his experience conducting the research project. The research partnership stems from the ongoing collaborators and Northwest Territories community interests in the downstream effects of permafrost thaw.