Diffenbaugh Noah S
Department of Earth System Science, Stanford University, Stanford, CA, USA.
Woods Institute for the Environment, Stanford University, Stanford, CA, USA.
Sci Adv. 2020 Mar 18;6(12):eaay2368. doi: 10.1126/sciadv.aay2368. eCollection 2020 Mar.
Independent verification of anthropogenic influence on specific extreme climate events remains elusive. This study presents a framework for such verification. This framework reveals that previously published results based on a 1961-2005 attribution period frequently underestimate the influence of global warming on the probability of unprecedented extremes during the 2006-2017 period. This underestimation is particularly pronounced for hot and wet events, with greater uncertainty for dry events. The underestimation is reflected in discrepancies between probabilities predicted during the attribution period and frequencies observed during the out-of-sample verification period. These discrepancies are most explained by increases in climate forcing between the attribution and verification periods, suggesting that 21st-century global warming has substantially increased the probability of unprecedented hot and wet events. Hence, the use of temporally lagged periods for attribution-and, more broadly, for extreme event probability quantification-can cause underestimation of historical impacts, and current and future risks.
对特定极端气候事件的人为影响进行独立验证仍然难以实现。本研究提出了一个用于此类验证的框架。该框架表明，先前基于1961 - 2005年归因期发表的结果经常低估全球变暖对2006 - 2017年期间前所未有的极端事件概率的影响。这种低估在炎热和潮湿事件中尤为明显，干旱事件的不确定性更大。这种低估反映在归因期预测的概率与样本外验证期观测到的频率之间的差异上。这些差异主要是由归因期和验证期之间气候强迫的增加所解释的，这表明21世纪的全球变暖大幅增加了前所未有的炎热和潮湿事件的概率。因此，使用时间滞后的时期进行归因——更广泛地说，用于极端事件概率量化——可能会低估历史影响以及当前和未来的风险。
