Forecasting Fluctuations in Bioclimatic Humidification Zones Under Climate Change Conditions

Understanding potential bioclimate changes is key to developing effective adaptation measures. Using integrated GIS, Selyaninov’s hydrothermal coefficient (HTC), and model data from the CORDEX project, the study examined fluctuations in various humidification biozones in southern Russia under representative RCP 2.6 and RCP 8.5 scenarios for the period 2021–2100. Scenario analysis based on the MOHC-HadGEM2-ES (GERICS-REMO2015) combination revealed heterogeneous responses of bioclimatic conditions. At RCP 2.6, the total humidification level will increase and reach a maximum in the period 2071–2080, when the semi-desert and desert biozone will not appear, and the zone of deciduous forests will expand to the north–west of the region and cover an area of 150.715 thousand km2. At RCP 8.5, the humidification level will decrease, which will lead to the dominance of the biozones of the dry steppe, semi-desert and desert. As a result, by 2100, the arid biozones will cover approximately 546.739 thousand km2 or 92.5% of the region’s territory. According to the resulting models, the areas of biozones are significantly dependent on fluctuations in temperature and precipitation, and these factors explain up to 82.7% of their variability. The methodological approach presented can be applied to assess the dynamics of bioclimatic humidification zones in other regions of the world.