Drier tropical and subtropical Southern Hemisphere in the mid-Pliocene Warm Period

Here we investigate rainfall changes in the mid-Pliocene Warm Period (similar to 3 Ma), a time when temperatures were 2-3 degrees C warmer than the pre-industrial era, using output from the Pliocene Model Intercomparison Projects phases 1 and 2 and sensitivity climate model experiments.

In the Mid-Pliocene simulations, the higher rates of warming in the northern hemisphere create an interhemispheric temperature gradient that enhances the southward cross-equatorial energy flux by up to 48%. This intensified energy flux reorganizes the atmospheric circulation leading to a northward shift of the Inter-Tropical Convergence Zone and a weakened and poleward displaced Southern Hemisphere Subtropical Convergences Zones.