Unveiling the connection: global warming and extreme weather in Southwest and East Asia

The recent surge in extreme summer weather events, such as severe heatwaves and flooding, in East Asian monsoon areas is widely attributed to the effects of global warming ^1,2 . Numerous studies based on global climate models have confirmed a strong correlation between the rise in extreme precipitation and heatwaves in these areas and the ongoing trend of global warming ^3,4,5 . However, while these studies provide valuable insights, they have yet to propose fluid-dynamical theories that could offer a deeper understanding and more reliable forecasts connecting global warming to summer extreme events. Here, we validate a theoretical concept ⁶ suggesting that the decrease in background zonal wind leads to an intensification of planetary-scale atmospheric responses. This validation is based on idealized numerical simulations and reanalysis data. Specifically, the intensification of the North Pacific Subtropical High (NPSH) results in stronger lower-level southerly winds, transporting hot and moist air from low latitudes to high latitudes. Consequently, the strengthening of the NPSH creates favorable conditions for heavy rainfall in Southeast Asia and extreme heat events in Japan and Korea. Global warming exacerbates this phenomenon as high-latitude areas experience more warming compared to lower latitudes, causing a decrease in background zonal wind over the North Pacific Ocean. This reduction in wind speed can intensify the response of the planetary-scale atmosphere over the region. Therefore, the observed increase in extreme summer weather events in Asian Monsoon regions is likely closely linked to ongoing global warming.