CMIP6 Climate Model Ensemble-Based Assessment of Future Changes in Air Temperature and Atmospheric Precipitation over Uzbekistan under SSP Scenarios

Abstract

Reliable projections of temperature and precipitation underpin water and agricultural planning in arid Central Asia, yet most Coupled Model Intercomparison Project Phase 6 (CMIP6) assessments for the region are domain-averaged and do not resolve the contrasting physical-geographical zones of Uzbekistan. This study assesses projected changes in both variables over the national territory using observation-constrained CMIP6 ensembles under three Shared Socioeconomic Pathway (SSP) scenarios. Historical simulations from 51 models were interpolated to 34 meteorological stations spanning 64 to 2,127 m above sea level (a.s.l.) and ranked against observations for 1991–2014 on a composite score built from absolute bias, error and anomaly correlation. Models ranking in the top ten and offering complete scenario coverage were retained, giving a four-model temperature ensemble and a three-model precipitation ensemble. Bias correction specific to each model, station and month was derived over the baseline and held fixed to 2100. Both ensembles outperform every individual member, with the annual anomaly root mean square error (RMSE) falling to 0.54 °C for temperature and to 24.2% for precipitation. Warming is large, spatially near-uniform and strongly scenario-dependent, reaching +1.34, +2.53 and +4.91 °C for 2071–2100 under the three pathways, with a range across stations of only 0.31 °C under the highest. Precipitation increases by +2.7, +7.2 and +9.5%, but lies well below the 24.2% validation error and the scenario distributions overlap in every decade, so they constrain the direction of the change rather than its magnitude. The increase falls almost entirely in winter and spring and accrues mainly in the mountain zone, and is no relief of water stress in the irrigated lowlands.CMIP6; SSP Scenarios; Multi-Model Ensemble; Bias Correction; Precipitation Anomaly; Temperature Anomaly; Central Asia; Uzbekistan