On the Linearity of the Extreme Precipitation Response to Increasing CO2 and Global Warming in CNRM-CM6-1

Abstract:

The regime of extreme precipitation is expected to be altered by the increasing CO2 level and related global warming. The increase in atmospheric temperature translates to enhanced atmospheric water content but also potential dynamical effects that drive the precipitation changes. There is considerable disagreement among climate models regarding the response of extreme precipitation to warming, especially in the tropics. Interestingly, some models exhibit a fairly linear response to both CO2 and global warming levels, while others do not. The discrepancies in patterns and rates of change can result from different assessment methods, study periods, ensemble sizes and model subsets. Here we perform a global analysis of the extreme precipitation response to different levels of global warming and CO2 using extended experiments from a single model (CNRM-CM6-1). The primary goal of the study is to split the precipitation response to CO2 (fast adjustment) versus global warming (slower response), assess the linearity of both individual responses, and evaluate their additivity in global climate projections where CO2 and global mean temperature evolve in parallel.