Global dryland area  is projected to expand by ~10% by 2100 compared to 1961-1990 under a high emission scenario . However, there are significant regional differences in the drivers of dryland expansion and subsequent estimates of change in dryland extent. Subtropical drylands are projected to expand as the climate in these regions shifts from temperate to subtropical and aridity increases in currently sub-humid subtropical regions, resulting in the loss of temperature-controlled seasonal cycles . Observed and projected warming and drying trends are most severe in transitional climate regions between dry and wet climates, with some exceptions , which are often highly populated agricultural regions with fragile ecosystems . In contrast, P - E predicts decreasing drought stress across temperate Asia and central Africa . Expansion of arid regions is anticipated in southwest North America, the northern fringe of Africa, southern Africa and Australia. The main areas of semiarid expansion are expected to occur in the north side of the Mediterranean, southern Africa, and North and South America. In contrast, India, eastern equatorial Africa and other areas of the southern Saharan regions are projected to have shrinking drylands . Future projections may underestimate dryland expansion, since the Coupled Model Intercomparison Project 5  models underestimate historical warming  and overestimate precipitation over drylands, particularly in the semiarid and dry sub-humid regions . However, estimates vary depending on the metric used . Studies based on off-line aridity and drought metrics  project strong surface drying trends , while projections based on total soil water availability from CMIP5 models show weaker and less extensive drying . In contrast, projections in southern Africa may overestimate future drying, with systematic rainfall biases being found in the present-day climatology in models that simulate extreme future drying . Improvements in projections of future changes in aridity require better understanding of seasonality, land hydrology and the feedbacks between projected soil moisture decrease on land surface temperature, relative humidity and precipitation .
IPCC
Climate Change 2022: Impacts, Adaptation and Vulnerability
IPCC Report