Dry and warm conditions in Australia exacerbated by aerosol reduction in China

Abstract. A substantial decline in anthropogenic aerosols in China has been observed since the initiation of clean air actions in 2013. Concurrently, Australia experienced anomalously dry and warm conditions in 2010s. This study reveals a linkage between aerosol reductions in China and the drying and warming trends in Australia during 2013–2019 based on aerosol-climate model simulations and multi-source observations. Aerosol decline in China triggered alterations in temperature and pressure gradients between the two hemispheres, leading to intensified outflow from Asia towards the South Indian Ocean, strengthening the Southern Indian Subtropical High and its related Southern Trade Winds. Consequently, this atmospheric pattern resulted in a moisture divergence over Australia. The reduction in surface moisture further resulted in more surface energy being converted into sensible heat instead of evaporating as latent heat, warming the near-surface air. Aerosol reductions in China are found to contribute to 19 % of the observed decreases in precipitation and relative humidity and 8 % of the increase in surface air temperature in Australia during 2013–2019. The intensified dry and warm climate conditions during 2013–2019 further explain 12 %–19 % of the increase in wildfire risks during fire seasons in Australia. Our study illuminates the impact of distant aerosols on precipitation and temperature variations in Australia, offering valuable insights for drought and wildfire risk mitigation in Australia.