Global warming, desertification/degradation, and droughts in arid regions

Applications of the concept of climatic desertification are considered. They include an approach to a separate assessment of aridization and degradation of arid lands and an approach to identifying “islands” of desertification from satellite data. It is established that the contribution of anthropogenic land degradation to desertification is confirmed by a significant linear trend of interannual fluctuations of satellite indicators of pasture digression in all the studied arid areas of Russia and Mongolia in the period 2000–2016. Significant trends in the intensification of aridization were characteristic only for a part of arid areas. Because of the excessive pastoral digression in arid areas, “islands” of desertification of anthropogenic origin are formed. The lifetime of such “islands” is determined by human influence and fluctuations in the humidity of the climate. An additional factor in the short-term decline in the life of the “islands” in Mongolia is the catastrophic death of livestock as a result of natural disasters (drought, zuta). The “island” of desertification, of natural origin, is found in the reserved part of the Sonora Desert, where rainy seasons and droughts determine the spread of aridization. Particular attention is paid to the analysis of trends in climatic characteristics. The increase in air temperature occurred in all the areas under study. Negative trends in annual and seasonal precipitation dominated the steppe zone of Russia during the periods 1936–1960 and 1991–2016, when the surface temperature of the North Atlantic was above normal. On the contrary, positive precipitation trends, weakening aridization, were observed in the period 1961–1990, corresponding to a temperature below the norm.