Feedbacks upon feedbacks: Rock weathering and the climate

“Look, we finally found out that we can explain this apparent discrepancy,” Hilton said. In other words, weathering of organic carbon increased the warming initiated by volcanic CO₂So the planet got warmer than it would have been from volcanic CO alone₂ Was emitted.

But Ragenstein doubts the amount of CO₂ Issued by weather. “Their estimate of the total amount of carbon delivered by this feedback is very large,” said Rugenstein. “I find it hard to believe that these carbon flows are going to be as big as they think.”

Where does that leave Earth’s “thermostat”?

If rock weathering emits CO₂Where does this leave our widely accepted understanding of Earth’s climate “thermostat”, where rock weathering (especially weathering of silicate minerals) occurs reduces down atmospheric CO₂Stopping uncontrolled global warming?

“Silicate weathering is still playing a major role. We’re not challenging it,” Hilton said. “This means that silicate weathering requires more effort.”

“Whereas [organic carbon weathering] There may be a big positive response, at the end, which tells you that the silicate weathering response should be even stronger,” Rugenstein said.

The strength of the competition between silicate weathering and organic carbon weathering depends on the amount of organic-carbon-rich sediment exposed on land. “At some point, you’ll run out of organic carbon to oxidize, and then there’ll be a tight limit on the strength of this feedback,” said Rugenstein.

In contrast, the amount of silicate minerals helps weather and reduce CO₂ It’s too much. “That’s why that feedback is ultimately more robust — we have a much bigger buffer to play with,” Rugenstein said.

A short-term, uncertain long-term effect for humans

The study shows that this response is likely to apply to other climate warming events, including the one we are experiencing today. Hilton predicts CO addition with organic carbon weathering₂ There will be a small amplifying effect of human-caused warming in the atmosphere over the next few centuries. “These are not disaster stations,” Hilton said, “but this is an amount of carbon that could be released at a higher rate than it is now, and that impacts our carbon budget.”