Climate Assumption Busted: Mega-Volcano, Falling CO₂

A recent piece in Eos highlights a result that will likely make climate modelers a bit uncomfortable: during one of Earth’s more dramatic volcanic episodes, atmospheric CO₂ didn’t spike—it fell. And not by a trivial amount, either.

We’re talking about roughly a 50% drop in atmospheric CO₂ during the emplacement of the Emeishan large igneous province (LIP) about 260 million years ago. That’s not a rounding error. That’s a regime shift. The standard storyline goes something like this: large-scale...