The Yangtze River basin experienced extreme flooding during the summer of 2020, leading to widespread impact and significant economic losses. However, there is a lack of specific and quantitative anthropogenic attribution analysis. Here, we used the VIC model and the Risk Ratio framework to isolate the contributions of two anthropogenic (ANT) forcings, aka greenhouse gas (GHG) and aerosol (AER), to this event and the associated potential risk. We also assessed future risk by employing projections from four simulations under the SSP2–4.5 scenario in 2041–2100. Our findings reveal that ANT forcing reduces the probability by 74 %, while GHG forcing increase it by 6 %, and AER forcing decreases it by 92 % at the downstream Datong station. At the middle-stream Cuntan station, ANT forcing decreases the probability of extreme floodings similar to the 2020 event by 87 %, while GHG forcing decreases it by 82 %, and AER forcing decreases it by 95 %. In the future period under the SSP2–4.5 scenario, ANT forcing reduces the probability of extreme flood events like 2020 by 78 % and 82 % at the Cuntan and Datong stations, respectively. And The GHG and AER forcings contribute positively and negatively to the probability of flooding in the Yangtze River Basin, respectively, mainly through influencing the probability of extreme precipitation and potential evapotranspiration. Our study provides valuable insights for policymakers to comprehend the anthropogenic influence on extreme flooding and to guide effective risk management strategies.

中文翻译：

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人为强迫降低了 2020 年长江特大洪水的概率和未来风险


长江流域在 2020 年夏季经历了特大洪水，造成了广泛的影响和重大的经济损失。然而，缺乏具体和定量的人为归因分析。在这里，我们使用 VIC 模型和风险比框架来隔离两种人为 （ANT） 强迫，即温室气体 （GHG） 和气溶胶 （AER），对这一事件和相关潜在风险的贡献。我们还通过在 2041-2100 年 SSP2-4.5 情景下采用四个模拟的预测来评估未来风险。我们的研究结果表明，在下游大同站，ANT 强迫降低了 74 % 的概率，而 GHG 强迫增加了 6 %，AER 强迫降低了 92 %。在中游 Cuntan 站，ANT 强迫将类似于 2020 年事件的极端洪水的可能性降低了 87%，而 GHG 强迫将其降低了 82 %，AER 强迫将其降低了 95 %。在 SSP2-4.5 情景下，ANT 强迫将 2020 年等极端洪水事件的概率分别降低了 78% 和 82% 在 Cuntan（村滩）站和 Datong 站（82%）。GHG 和 AER 强迫分别对长江流域洪涝概率产生正向和负向贡献，主要通过影响极端降水和潜在蒸散发的概率。我们的研究为政策制定者理解人为对极端洪水的影响并指导有效的风险管理策略提供了有价值的见解。