Central Asia lies in the interior of the Eurasian continent and is characterised by a predominantly arid to semi-arid climate. Water availability in this region is limited and strongly controlled by precipitation, particularly during winter. Snow accumulated in winter serves as a critical water reservoir, which is released during spring melt and sustains river discharge, agriculture, and ecosystems. However, precipitation in Central Asia is not only scarce but also highly variable from year to year. This strong variability makes the regional water cycle especially sensitive to changes in the climate system. As a result, the region frequently experiences both severe droughts and unusually wet conditions, posing ongoing risks to water security, food production, and socio-economic stability.

For decades, research has largely attributed year-to-year changes in Central Asian precipitation to tropical climate variability, especially the El Niño–Southern Oscillation (ENSO). Yet observations have long suggested that ENSO alone cannot fully explain the variability, particularly during years with pronounced anomalies. This gap has pointed to the possible influence of additional, previously overlooked climate drivers.

A new study published in npj Climate and Atmospheric Science reveals that Antarctic ozone variability provides such a missing link. The research, led by YAO Mengyuan from the Institute of Atmospheric Physics, Chinese Academy of Sciences, together with TANG Haosu from the University of Sheffield and HUANG Gang from the Institute of Atmospheric Physics, in collaboration with James Screen from the University of Exeter, shows that changes in Antarctic ozone during boreal autumn can significantly influence winter precipitation in Central Asia.

“Antarctic ozone has long been recognised as a key signal of human influence on the climate system,” said HUANG Gang, one of the corresponding authors. “What we show here is that its variability is not only important locally, but can also affect hydroclimate in distant regions, including Central Asia.”

The study combines multiple lines of evidence, including observational datasets, reanalysis products, and climate model experiments. It identifies a robust statistical relationship between autumn Antarctic ozone and subsequent winter precipitation in Central Asia. Importantly, this relationship is largely independent of ENSO, suggesting that Antarctic ozone provides an additional and complementary source of predictability.

The researchers also uncover the physical mechanisms behind this long-range connection. In the stratosphere, higher Antarctic ozone levels lead to warming over the polar region, which weakens the polar vortex and reduces the strength of high-latitude westerly winds. This signal propagates downward into the troposphere over timescales of weeks to months, shifting the Southern Annular Mode into its negative phase. As a result, large-scale circulation patterns adjust, with westerly jets moving equatorward and pressure patterns reorganising across the Southern Hemisphere.

These changes trigger a reconfiguration of the meridional circulation. Enhanced upward motion in the Southern Hemisphere mid-latitudes and associated cross-equatorial energy transport influence the Northern Hemisphere Hadley circulation, shifting mid-latitude atmospheric circulation southward. Over Central Asia, this leads to increased low-level moisture convergence and stronger upward motion, both of which favour enhanced winter precipitation.

In addition to this atmospheric pathway, Antarctic ozone variability also influences ocean–atmosphere interactions. Changes in surface winds associated with the Southern Annular Mode modify ocean circulation through Ekman transport, creating a dipole pattern of sea surface temperature anomalies in the Southern Ocean. This pattern can persist and extend toward lower latitudes, eventually exciting Rossby wave trains that propagate across hemispheres. These waves alter tropical circulation, promote warming in the central-eastern Pacific, and weaken zonal atmospheric circulation along the equator. The resulting shift in tropical convection further enhances upper-level divergence over Central Asia, reinforcing precipitation anomalies.

“Taken together, these processes show how a signal originating in the Antarctic stratosphere can cascade through the climate system and influence rainfall thousands of kilometres away,” said TANG Haosu, also the corresponding author of the study. “It highlights the importance of considering cross-hemispheric linkages when we study regional climate variability.”

Building on these insights, the study develops a statistical prediction model that combines Antarctic ozone and ENSO as joint predictors of Central Asian winter precipitation. The results show that including ozone variability significantly improves predictive skill compared to using ENSO alone, offering a new pathway for seasonal climate forecasting.

The findings also have important implications for future climate risk. The study suggests that combinations between Antarctic ozone variability and ENSO may amplify precipitation-related risks in Central Asia under a changing climate. Compared with scenarios that consider ENSO alone, the inclusion of ozone effects points to greater potential impacts on population exposure and economic activity.

This work provides new evidence that the Antarctic is not only a region strongly affected by climate change, but also an active driver of climate variability at lower latitudes. By linking stratospheric processes to regional hydroclimate, the study advances understanding of how different components of the Earth system interact across vast distances.

As climate variability continues to evolve, identifying new sources of predictability will be essential for improving water resource management and climate adaptation in vulnerable regions. The authors suggest that incorporating high-latitude signals such as Antarctic ozone into forecasting systems could help provide more reliable and actionable information for decision-makers in Central Asia and beyond.

Paper info:

Yao, M., Tang, H.*, Huang, G.*, & Screen, J. A. (2026). Antarctic Ozone as a Precursor to Winter Central Asian Precipitation Beyond ENSO. Npj Climate and Atmospheric Science. https://doi.org/10.1038/s41612-026-01423-7