Risser Mark D, Collins William D, Wehner Michael F, O'Brien Travis A, Huang Huanping, Ullrich Paul A
Climate and Ecosystem Sciences Division, Lawrence Berkeley National Lab, Berkeley, CA, USA.
Earth and Environmental Sciences Area, Lawrence Berkeley National Lab, Berkeley, CA, USA.
Nat Commun. 2024 Feb 22;15(1):1318. doi: 10.1038/s41467-024-45504-8.
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.
全面了解人为因素对降雨的影响对于水资源管理和基础设施设计至关重要。然而，在区域尺度上，现有的检测和归因研究很少能够确凿地确定人类活动对降水的影响。在此，我们表明人为气溶胶和温室气体（GHG）排放是美国降水变化的主要驱动因素。温室气体排放增加了所有季节雨量计测量的平均降水量和极端降水量，而全球气溶胶排放的年代际尺度效应则减少了降水量。局部气溶胶排放在冬季和春季进一步抵消了温室气体增加的影响，但在夏季和秋季增强了降雨。我们的结果表明，关于历史降水趋势的相互矛盾的文献可以通过气溶胶和温室气体信号的抵消来解释。在美国尺度上，单个气候模型再现了观测到的变化，但无法确定给定的人为因素是增加还是减少了降雨量。
