CO 2 and Climate Change

Abstract
On time scales of tens of millions of years, climate is known to undergo massive changes. Previous evidence has suggested a link between natural atmospheric COvariability and these long-term climatic oscillations, but some recent studies have found discrepancies. In their Perspective, Crowley and Berner assess the evidence. They conclude that the COmodel is valid for high-latitude glaciations but that for low latitudes, altered tectonic settings and problems with interpreting climate indicators complicate the picture.