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The Eurasian Subtropical Westerly Jet (ESWJ), a key component of the Eurasia circulation system, has weakened in summer since 1979 due to uneven aerosol emissions. Its future evolution under human activities, including clean air policies, remains uncertain yet critical for climate adaptation in mid-latitude Asian drylands. Using multiscenario projections, we show that the ESWJ is projected to reverse its historical weakening trend and turn to strengthen during 2025–2100. This intensification arises from both increasing greenhouse gas (GHG) concentrations and declining anthropogenic aerosols. Aerosol reduction primarily triggers the transition from weakening to strengthening, already emerging around 2010, while GHG forcing additionally induces a southward displacement. These circulation changes enhance dynamic moisture advection into Central Asia, partially offsetting the “dry-get-drier” paradigm and resulting in limited changes in regional water availability. While recent studies have emphasized the warming effects of aerosol reduction, our findings highlight the critical role of circulation dynamics in shaping regional hydroclimatic security.
Jiang et al. (Wed,) studied this question.