Uncovering anthropogenic forcing and atmospheric dynamic controls on global extreme precipitation

Abstract: Anthropogenic forcing is expected to increase atmospheric moisture content and intensify precipitation extremes. However, extreme precipitation sensitivity to temperature is complicated by the presence of reduced or hook-shaped scaling, and the underlying physical mechanisms remain unclear. By using atmospheric reanalysis and climate model outputs, we propose a physical decomposition of extreme precipitation scaling into anthropogenic thermodynamic and dynamic components at the global scale in both historical and future climates. Interestingly, we find that anthropogenic thermodynamic terms do not always contribute to precipitation intensification, with partial components offsetting positive precipitation sensitivity to rising temperature. Large anomalies in future precipitation sensitivity are dominated by dynamic variations, with a contrast of positive anomalies over oceans and negative anomalies over land areas. Our findings reveal counteracting effects of anthropogenic thermodynamics and atmospheric dynamic controls on extreme precipitation, and underscore the importance of more detailed understanding on anthropogenic thermodynamic effects on extreme events.