Anthropogenic aerosols mask increases in US rainfall by greenhouse gases

Mark D Risser; William D Collins; Michael F Wehner; Travis A O'Brien; Huanping Huang; Paul A Ullrich

doi:10.1038/s41467-024-45504-8

Anthropogenic aerosols mask increases in US rainfall by greenhouse gases

Nat Commun. 2024 Feb 22;15(1):1318. doi: 10.1038/s41467-024-45504-8.

Authors

Mark D Risser^#¹, William D Collins^#^{2

3}, Michael F Wehner⁴, Travis A O'Brien^{5

6}, Huanping Huang^{5

7}, Paul A Ullrich^{8

9}

Affiliations

¹ Climate and Ecosystem Sciences Division, Lawrence Berkeley National Lab, Berkeley, CA, USA. mdrisser@lbl.gov.
² Earth and Environmental Sciences Area, Lawrence Berkeley National Lab, Berkeley, CA, USA.
³ Department of Earth and Planetary Science, University of California, Berkeley, CA, USA.
⁴ Applied Mathematics and Computational Research Division, Lawrence Berkeley National Lab, Berkeley, CA, USA.
⁵ Climate and Ecosystem Sciences Division, Lawrence Berkeley National Lab, Berkeley, CA, USA.
⁶ Department of Earth and Atmospheric Sciences, Indiana University, Bloomington, IN, USA.
⁷ Department of Geography and Anthropology, Louisiana State University, Baton Rouge, LA, USA.
⁸ Program for Climate Model Diagnosis & Intercomparison, Lawrence Livermore National Laboratory, Livermore, CA, USA.
⁹ Department of Land, Air, and Water Resources, University of California, Davis, CA, USA.

^# Contributed equally.

Abstract

A comprehensive understanding of human-induced changes to rainfall is essential for water resource management and infrastructure design. However, at regional scales, existing detection and attribution studies are rarely able to conclusively identify human influence on precipitation. Here we show that anthropogenic aerosol and greenhouse gas (GHG) emissions are the primary drivers of precipitation change over the United States. GHG emissions increase mean and extreme precipitation from rain gauge measurements across all seasons, while the decadal-scale effect of global aerosol emissions decreases precipitation. Local aerosol emissions further offset GHG increases in the winter and spring but enhance rainfall during the summer and fall. Our results show that the conflicting literature on historical precipitation trends can be explained by offsetting aerosol and greenhouse gas signals. At the scale of the United States, individual climate models reproduce observed changes but cannot confidently determine whether a given anthropogenic agent has increased or decreased rainfall.