Spatiotemporal shifts in humidification zones: assessing climate impact on bioclimatic landscapes.

Climate change is a global problem that is accompanied by the significant changes in humidification conditions in many regions all over the world. The study examined spatiotemporal changes in humidification zones in southern Russia in the period 1961-2020. Humidification zones were determined in accordance with the classification of the Selyaninov hydrothermal coefficient. During the research period, a significant increase in average annual temperatures was noted for the region (+ 0.31 °C/decade) and generally positive, but insignificant, dynamics of annual precipitation (+ 4.80 mm/decade). These changes were accompanied by a significant shift in the humidification zones. Despite some periods of decline, the territories of semi-desert and desert zones, as well as dry steppes, have significantly expanded from the east of the region to the west in the last decade. The expansion of these zones was primarily due to a reduction in the area of the more humid steppe zone, with a lesser contribution from the forest-steppe zone. Overall, during the study period, the area of semi-desert and desert zone expanded by an average of + 5.505 thou km²/decade. The zone of the Taiga and deciduous forests has not undergone significant changes. The results obtained indicate arid warming and a general deterioration in humidification conditions in most of southern Russia in the period 1961-2020. According to calculations, further warming, other things being equal, can lead to an even greater expansion of the semi-desert and desert bioclimatic zone, which can provoke a number of socio-economic and environmental problems, especially in the eastern part of the region.