Effects of temperature overshoot amplitude on regional climate

Abstract

Overshooting a global temperature target before returning back to the target using negative emissions is increasingly being discussed in light of ongoing emissions inconsistent with achieving the goals of the Paris Agreement. While global temperature is widely expected to be reversible under such conditions, regional climate responses are much less well understood. We analyse results from two CMIP6 overshoot scenarios run by an ensemble of Earth system models to assess changes in temperature and precipitation across the globe. We find that overshooting a temperature target by a larger amount leads to a warmer Southern Hemisphere, a cooler Northern Hemisphere, and larger decreases of precipitation in North Africa and increases in East Asia, compared to a smaller temperature overshoot. Some differences, notably increases in extreme temperatures, persist for centuries after the overshoot. These findings show that reversal of global temperatures will not be felt evenly across the globe and that the size of an overshoot matters long term.