Increasing weather extremes in China attributed to rising greenhouse gases and declining aerosols

Rising global temperatures have intensified warm-season climate extremes over China in recent decades. This study examines changes in extreme temperature and precipitation during May–September and their links to greenhouse gas (GHG) increases and aerosol reductions, using observations, reanalysis data, and climate model simulations. During 2011–2023, daily maximum temperature (TXx), heatwave frequency, and heatwave mean duration show significant upward trends of 0.70 °C per decade, 3.77 days per decade, and 0.31 days per event per decade, respectively. Attribution analysis indicates that rising CO₂ concentrations contribute 43% ± 3% of the TXx increase, while declining aerosol optical depth, decreasing at 0.054 per decade due to improved air quality, accounts for 27% ± 3%. In eastern China, where aerosol reductions are strongest, aerosol decline explains up to 79% ± 10% of the TXx increase, amplifying heatwave intensity and persistence.

Extreme precipitation has also become more intense and frequent. A marked acceleration occurred around 2010, with the trend in accumulated extreme precipitation (R95pTOT) increasing from 2.88 mm per decade during 2000–2010 to 22.88 mm per decade during 2010–2023. This acceleration is largely driven by the reversal of aerosol trends associated with China’s clean air actions, which affect cloud microphysics and atmospheric dynamics and account for roughly half of the change in R95pTOT trends. Model projections suggest that continued aerosol reductions under carbon neutrality pathways will further intensify extreme precipitation, outweighing the effect of GHG forcing alone. These results highlight the critical role of both GHGs and aerosols in shaping recent and future warm-season climate extremes over China.