Magnitude uncertainty dominates intermodel spread in zonal-mean precipitation response to anthropogenic aerosol increase

Anthropogenic aerosols are an important driver of historical climate
change, but the climate response is not fully understood, and the climate
model simulations suffer from large uncertainties. Based on a multi-model
ensemble of historical aerosol forcing simulations for a period of global
aerosol increase during 1965–1989, here, we show that the precipitation
response shares a common southward displacement of the tropical rain band,
but the magnitude differs markedly among models, accounting for 76% of the
intermodel uncertainty in zonal-mean precipitation change. Our analysis of
atmospheric energetics further reveals key mechanisms for magnitude
uncertainty: aerosol radiative forcing drives, cloud radiative feedback
amplifies, and ocean circulation damps the intermodel uncertainty in
cross-equatorial atmospheric energy transport change and the meridional
shift of tropical rain bands. This has important implications for
understanding and reducing intermodel uncertainty in anthropogenic climate
change.