Human-Caused Long-Term Changes in Global Aridity
Long-term aridity changes in the globe and each hemisphere were investigated using observation-based aridity reconstructions and the latest CMIP6 factorial simulations.
We provided the clear evidence of a discernible human fingerprint on global aridity changes for 1965-2014, and demonstrated greater future aridification than the default CMIP6 simulations by applying the scaling factors from optimal detection and attribution. We highlighted future reductions in aridity will rely primarily on the mitigation of greenhouse gas emissions.
Widespread aridification of the land surface causes substantial environmental challenges and is generally well documented. However, the mechanisms underlying increased aridity remain relatively underexplored. In this study, we have high confidence that the intensified aridification across broad spatial scales was caused primarily by human activity between 1965 and 2014. Within the verified anthropogenic effects, the greenhouse gas emissions dominated the long-term observed drying tendencies around the globe, as well as two hemispheres; and the aerosols mitigated these drying trends as a secondary affecting factor of aridity. Stronger future aridity changes projected by the constrained CMIP6 simulations suggest more pressing environmental challenges that will likely face society.