Feedbacks upon feedbacks: Rock weathering and the climate

“Lo and behold, we end up finding that we can explain this apparent discrepancy,” said Hilton. In other words, weathering of organic carbon amplified the warming initiated by volcanic CO2, so the planet warmed more than it would have if only the volcanic CO2 had been emitted.

But Rugenstein is skeptical of the amount of CO2 released by the weathering. “Their estimates of the total amount of carbon delivered by this feedback are enormous,” said Rugenstein. “I find it difficult to believe that these carbon fluxes are going to be as big as they think they are.”

Where does that leave Earth’s “thermostat”?

If rock weathering emits CO2, where does this leave our widely accepted understanding of Earth’s climate “thermostat,” where weathering of rock (specifically weathering of silicate minerals) reduces atmospheric CO2, preventing runaway global warming?

“Silicate weathering is still playing a major role. We’re not challenging that,” said Hilton....

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