Convection-permitting climate models offer more certain extreme rainfall projections

Abstract Extreme precipitation events leads to dramatic impacts on society and the situation will worsen under climate change1. Decision-makers need reliable estimates of future changes as a basis for effective adaptation strategies, but projections at local scale from regional climate models (RCMs) are highly uncertain2. Here we exploit the first km-scale convection-permitting model (CPM) ensemble to provide new understanding of the changes in local precipitation extremes and related uncertainties over the greater Alpine region. The CPM ensemble shows a stronger increase in the frequency and intensity of extreme events than the driving RCM ensemble, during the summer when convection dominates. We find that the CPM ensemble substantially reduces the model uncertainties and their contribution to the total uncertainties of more than 50%. We conclude that the more realistic representation of local dynamical processes in the CPMs provides more reliable and less uncertain local estimates of change essential for policymakers.