Massive ice sheets weirdly warmed us up
A new study, lead by Mark Torres, makes the surprising suggestion that the glaciers that grow during cold periods actually tend to drive warming.
During ice ages, glaciers wear down and dissolve rock. This speeds up chemical reactions with the dissoved minerals in the rock that release carbon stored in rocks and in the ocean into the the atmosphere in the form of carbon dioxide. That CO2 then leads to warming.
Then as the glaciers melt, the carbon release stops, and the climate cools again and a new ice age begins.