Limited Carbon Cycle Response to Increased Sulfide Weathering Due to Oxygen Feedback

The chemical weathering of sulfide-bearing rocks can result in the dissolution of carbonate rocks leading to degassing of CO2 to the atmosphere. While this process has been argued to be a significant geologic source of CO2, it also perturbs the geological cycles of oxygen and sulfur, triggering a cascade of geochemical feedbacks. Using a numerical model of geochemical cycles and climate, we found that due to feedbacks on atmospheric oxygen associated with the organic carbon cycle, an increase of sulfide weathering leads to a limited source of CO2 followed by a longer sink of CO2. This result is due to the stoichiometry of sulfide weathering where more O2 is consumed than CO2 is released. If sulfide weathering increases progressively on a geological timescale, the duration of the carbon source is extended, but its magnitude is negligible before it becomes a carbon sink.

Automated summary

Chemical weathering of sulfide-bearing rocks can lead to the release of CO2 into the atmosphere, disrupting the geological cycles of oxygen and sulfur and triggering geochemical feedbacks. A numerical model shows that due to feedbacks on atmospheric oxygen associated with the organic carbon cycle, increased sulfide weathering results in a limited source of CO2 followed by a longer period of CO2 absorption.