CICERO - Center for International Climate Research

Fast and slow precipitation responses to individual climate forcers: A PDRMIP multimodel study

Bjørn Hallvard Samset, Gunnar Myhre, Piers M. Forster, Øivind Hodnebrog, Timothy Andrews, Gregory S. Faluvegi, Dagmar Fläschner, Matthew Kasoar, Viatcheslav V. Kharin, Alf Kirkevåg, Jean-François Lamarque, Dirk Jan Leo Oliviè, Thomas Benjamin Richardson, Drew T. Shindell, Keith P. Shine, Toshihiko Takemura, Apostolos Voulgarakis

Precipitation is expected to respond differently to various drivers of anthropogenic climate change. We present the first results from the Precipitation Driver and Response Model Intercomparison Project (PDRMIP), where nine global climate models have perturbed CO2, CH4, black carbon, sulfate, and solar insolation. We divide the resulting changes to global mean and regional precipitation into fast responses that scale with changes in atmospheric absorption and slow responses scaling with surface temperature change. While the overall features are broadly similar between models, we find significant regional intermodel variability, especially over land. Black carbon stands out as a component that may cause significant model diversity in predicted precipitation change. Processes linked to atmospheric absorption are less consistently modeled than those linked to top-of-atmosphere radiative forcing. We identify a number of land regions where the model ensemble consistently predicts that fast precipitation responses to climate perturbations dominate over the slow, temperature-driven responses.

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