Projected changes in precipitation and air temperature over the Volga River Basin from bias-corrected CMIP6 outputs

Abstract

This paper investigates future changes in annual mean precipitation and air temperature across the Volga River basin, which serve as significant drivers of climate-induced changes in the Volga River's discharge, the primary input to the Caspian Sea. The thirteen Global Climate Models (GCMs) outputs under four Shared Socioeconomic Pathways (SSPs) scenarios ) from the sixth phase of Coupled Model Intercomparison Project (CMIP6) were used for this study. In the historical period , using comprehensive rating metrics and Taylor diagram, the GCMs are ranked according to their ability to capture the temporal and spatial variability of precipitation and air temperature. The Multi-Model Ensemble (MME) is generated, and bias-correction techniques are utilized to reduce the uncertainties and correct the biases in CMIP6 outputs. Bias-correction techniques were assessed during the historical period and an average of appropriate methods were utilized for future projections . In the 21st century, future projections show that the Volga River basin could mainly experience a temperature increase of 0.4°C to 7.5°C, alongside a precipitation rise of 0.7% to 37%, depending on the scenarios considered. A comparison of future projections with an observational dataset from 2015 to 2017 indicates that the SSP2-4.5 is a more likely scenario to represent the future climate of the Volga River basin.