Response of precipitation extremes in South China to CO2 removal forcing

The reversibility of precipitation and extreme precipitation under the CO 2 removal scenario is critical for climate mitigation and adaptation. This investigation employs CMIP6 models to quantify responses of extreme precipitation indices in South China under an idealized carbon dioxide removal (CDR) scenario. Results reveal that restoring CO 2 concentrations to pre-industrial levels increases the extremeness of precipitation compared with historical benchmarks. Spatial pattern disparities between implementation phases indicate an increase in both total and extreme precipitation across South China during CDR deployment. Mechanistic analysis identifies distinct dynamical controls: humidity-driven precipitation increases are primarily governed by thermodynamic processes through vapor advection, supplemented secondarily by convergence–divergence effects. Similarly, advective enhancements associated with dynamic processes would further lead to the occurrence of precipitation and extreme precipitation. This study highlights that the implementation of CDR would have a limited effect on the mitigation of extreme precipitation in South China, and provides suggestions and references for risk assessment and climate adaptation. 二氧化碳移除情景下降水及极端降水的可逆性对气候减缓与适应至关重要.本研究基于CMIP6模式数据, 量化了二氧化碳移除情景下华南极端降水指数的响应特征.结果表明, 当二氧化碳浓度恢复至工业革命前水平时, 华南降水极端性较工业革命前有所增强.对比二氧化碳下降和上升阶段的差异发现, 华南总降水量与极端降水量均呈会增长.机理分析表明:热力驱动的降水增强主要受水汽平流过程主导, 水汽辐合辐散作用次之, 而动力项驱动的平流过程增强则会进一步促使降水与极端降水事件发生.本研究表明二氧化碳移除措施对华南极端降水的缓解作用有限, 可为区域风险评估与气候适应策略制定提供科学参考.