Mid-latitude Asian drylands, stretching from Central Asia to northern China, are among the largest dryland systems in the world. Home to extensive agricultural activities and fragile ecosystems, the region is highly vulnerable to climate change and water scarcity.
A thermodynamic perspective suggests that global warming will intensify dryness in arid regions, following the so-called “dry-get-drier” paradigm. However, a new study led by researchers from the Institute of Atmospheric Physics (IAP) of the Chinese Academy of Sciences (CAS) reveals that large-scale atmospheric circulation changes may partly offset this drying across Asian drylands.
The study, published in Science Advances on May 27, 2026, shows that the Eurasian Subtropical Westerly Jet (ESWJ), a narrow high-speed wind current high in the atmosphere, is projected to strengthen and shift southward during summer throughout the twenty-first century. These circulation changes are expected to enhance moisture advection into Central Asia, helping alleviate warming-induced drying.
Using projections from 40 climate models participating in the Coupled Model Intercomparison Project Phase 6 (CMIP6), the researchers found that both increasing greenhouse gases and declining anthropogenic aerosols contribute to strengthening the jet stream, while greenhouse gas forcing primarily drives its southward shift.
The researchers also found that the strengthened jet stream enhances dynamic moisture advection into northern Central Asia, while its southward shift increases moisture advection into southern Central Asia. These circulation-driven changes partly compensate for warming-related drying, resulting in limited changes in future water availability across much of the region.
More notably, the projected future strengthening of the ESWJ contrasts with its weakening in recent decades. The researchers found that reductions in anthropogenic aerosol emissions associated with clean air policies play a key role in reversing the historical weakening of the jet stream. Since the late 1970s, uneven aerosol emissions across Eurasia have weakened the summer ESWJ, contributing to drying in northern Central Asia. However, future aerosol reductions are projected to trigger a transition from weakening to strengthening, with signs of this reversal already emerging around 2010.
While some recent studies have suggested that aerosol reductions could lead to additional warming, the lead author Dr. Jie Jiang noted that aerosol reductions associated with cleaner air policies may also have important climate impacts beyond warming. She emphasized that understanding how atmospheric circulation responds to human activities is critical for improving projections of future regional climate risks and water security in dryland regions.
Science Advances
A strengthened and southward-shifted westerly jet mitigates warming-induced drying across Asian drylands
27-May-2026