Climate-driven 21st century Caspian Sea level decline estimated from CMIP6 projections

Abstract

Future Caspian Sea level change is estimated for the 21st century using 15 Coupled Model Intercomparison Project 6 climate models and three shared socioeconomic pathways. Projected evaporation increase is significantly larger than precipitation increase integrated over the Caspian Sea catchment basin, resulting in an increasingly negative water balance over the 21st century. A best-fit model analysis that resolves important model limitations related to spatial resolution, climate sensitivity, and Caspian Sea surface area suggests climate-driven sea level reductions of about 8 (inter-model range from 2 to 15) m and 14 (inter-model range from 11 to 21) m by the end of this century for the SSP245 and SSP585 scenarios, respectively. A sea level decline of these magnitudes will result in complete desiccation of the northern Caspian basin and will have adverse effects on ecosystems, coastal infrastructure, navigation, biodiversity, and economies of the entire Caspian region.