In the Arctic, where certain minerals react with oxygen, rocks release CO2 through chemical weathering. Sulfide minerals like fool's gold create acid during this process, which leads to CO2 release from nearby rocks. As permafrost thaws with rising temperatures, more of these minerals are exposed, potentially worsening climate change.
Previously, it was unclear how much CO2 this process could release as temperatures rise. Using data from 23 sites in Canada's Mackenzie River Basin, the largest in the country, the researchers tracked sulfate (SO4-2-) levels - a byproduct of sulfide weathering - across six decades. The study found that sulfide weathering increased by 45% from 1960 to 2020 as temperatures rose by 2.3 C. This suggests that CO2 emissions from weathering could significantly rise, doubling by 2100 to an estimated 3 billion kg annually, comparable to half of Canada's annual aviation emissions.
Lead author Dr. Ella Walsh commented, "We see dramatic increases in sulfide oxidation across the Mackenzie with even moderate warming. Until now, the temperature sensitivity of CO2 release from sulfide rocks and its main drivers were unknown over large areas and timescales."
The research showed that mountainous and permafrost areas saw the greatest increase in weathering, while regions with peatlands experienced less CO2 release. Peat acts as a barrier to weathering, offering some protection from the warming effects. Co-author Professor Bob Hilton added, "Future warming across vast Arctic landscapes could further increase sulfide oxidation rates and affect regional carbon cycle budgets. Now that we have found this out, we are working to understand how these reactions might be slowed down, and it seems that peatland formation could help to lower the sulfide oxidation process."
The study suggests this phenomenon is likely occurring in other Arctic regions with similar rock types and environmental conditions. These findings underscore the importance of including sulfide weathering in climate models to more accurately predict future climate scenarios.
'Records were provided by Environment Canada as part of its National Long-term Water Quality Monitoring Programme. Sulfate concentrations were measured using ion chromatography, which separates ions based on their charge.'
Research Report:Temperature sensitivity of the mineral permafrost feedback at the continental scale
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Department of Earth Sciences at the University of Oxford
Beyond the Ice Age
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