The Climate Change Impact on the Development of Droughts in Ukraine

The paper considers the peculiarities of the climate change influence on the dynamics of drought development in Ukraine. The analysis was performed for average long-term climatic conditions during the growing season (1981–2020) and under climate change scenarios RCP 4.5 and RCP 8.5 for the period of 2021–2050 (for the period as a whole and by the decades: 2021–2030, 2031–2040, 2041–2050). The drought development was studied over relatively short periods of time (ten days) at the main agroclimatic regions of Ukraine (Polissia, Forest-Steppe, Northern and Southern Steppe). The assessment of the aridity of ten-day periods was accomplished by means of a set of aridity indicators by Selyaninov, Shashko, Budagovskiy and Bova, which corrects and supplements each other; this made it possible to consider in detail the genesis of climate-induced drought in the agroclimatic regions of Ukraine. Analysis of the study results showed that the development of drought conditions in all agroclimatic regions is expected as early as in the first decade (2021–2030). According to both scenarios, from 4–6 in Polissia to 16–17 severe and very severe droughts in the Southern Steppe are expected. In the second decade (2031–2040), under RCP4.5, improvement in moistening conditions is expected in Polissia and Forest-Steppe and under RCP8.5, an increase in the level of aridity is expected in these agroclimatic regions. In the Northern Steppe and Southern Steppe the number of moderately, very and extremely dry ten-day periods will increase (from 9 to 17). In the third decade (2041–2050), under the RCP4.5 scenario, very severe aridity conditions are assumed in all agroclimatic regions. Under RCP8.5, good moistening conditions and, according to both criteria, a small number of dry ten-day periods are expected in Polissia and Forest-Steppe. As for the conditions at the Northern and Southern Steppes very severe drought conditions are expected (from 8 to 17 ten-day periods with moderate, severe and very severe drought). For 2021–2050 on the whole, there will be an increase in aridity during the growing season in all agroclimatic regions of Ukraine.