Simulated differences in 21st century aridity due to different scenarios of greenhouse gases and aerosols

Global climate models project global decreases of P/PET (drying) in the 21st century. We examine the uncertainty of aridity projections due to scenarios of greenhouse gases (GHGs) and aerosols with three sets of ensemble simulations from a single climate model, the Community Earth System Model (CESM1).

Ensembles consist of two Radiative Concentration Pathways (RCPs) and a scenario with RCP-like GHGs but with aerosol precursor emissions and atmospheric oxidants fixed at the year 2005 level. Under a high GHGs emission scenario (RCP8.5), global land P/PET decreases (drying) by 6.4 +/- 0.8 % in 2060-2080 relative to 1985-2005. A GHG mitigation scenario (RCP4.5) would reduce the drying (P/PET decrease) to 3.7 +/- 0.6 %.