Human influence on the unprecedented 2022 extreme dragon boat water event in South China: Insights from historical and projected perspectives

During May–June 2022, South China encountered an unprecedented extreme dragon boat water event (2022 EDBWE), characterized by persistent heavy precipitation. The maximum 31-day cumulative precipitation (Rx31day) from May 21 to June 20, was anomalously 74% higher than the historical average, breaking previous records and resulting in substantial socioeconomic damage and loss of life. Nevertheless, the extent to which human-induced climate change influenced the occurrence of the 2022 EDBWE, as well as its implications for the future likelihood of analogous events under different Shared Socioeconomic Pathway (SSP) scenarios, remains inadequately quantified. This study aims to address these uncertainties by employing data from the Detection and Attribution Model Intercomparison Project (DAMIP) and the Scenario Model Intercomparison Project (SIMIP) within the Coupled Model Intercomparison Project Phase 6 (CMIP6). We evaluate the effect of anthropogenic forcing on extreme precipitation similar to the 2022 EDBWE both in historical context and under future projections for South China. The results indicate that anthropogenic forcing has increased the probability of the event similar to the 2022 EDBWE by approximately 64% (90% confidence interval: -35% to +90%). Specifically, the greenhouse gas-only (GHG) forcing has raised the probability by +66% (+10% to +91%), while aerosol-only (AER) forcing has reduced the probability by -28% (-564% to +71%). Furthermore, under SSP scenarios—SSP1-2.6, SSP2-4.5, and SSP5-8.5—the likelihood of similar events rises significantly. By the end of the 21st century, the probability of an event akin to the 2022 EDBWE is projected to be about 11 times greater under the high-emission scenario (SSP5-8.5) compared to historical climate conditions. This study offers crucial insights for designing effective strategies to mitigate and adapt to climate change, especially in regions prone to extreme precipitation events.