Projected increase in the impacts of ENSO on hydroclimate over Central Asia

Abstract Central Asia (CA) is a region at risk of drought and desertification under a warming environment. Hence, further understanding of the drivers of CA hydroclimate is crucial for the production, ecological environment, and social security of this region. However, little is known about the impacts of the El Niño–Southern Oscillation (ENSO), a major mode of global climate variability, on future CA hydroclimate. Here we investigated the causal influence of ENSO on future CA hydroclimate using outputs from Coupled Modeling Intercomparison Project Phase 6 (CMIP6) models. We find significant causal effects of ENSO on precipitation, evaporation, soil moisture, and runoff over a large part of CA in the model simulations. ENSO is related to the restructuring of winds and atmospheric moisture sources over the tropical Indian Ocean, the Red Sea, and the CA, and thus directly influenced the CA hydroclimate. We showed that, compared to other major climate modes, ENSO exhibits a dominant effect on CA hydroclimate. Model projections indicate that future CA hydroclimate is likely to be linked to ENSO variations with high consistency between models and the likelihood of the hydroclimatic impacts of ENSO on CA may increase in the 21st century. This increase is associated with the extension of ENSO-driven moisture transport over southern and western CA. These findings underscore that ENSO may complicate the future hydroclimatic systems over CA.