The southern African climate under 1.5° and 2°C of global warming as simulated by CORDEX models

Abstract

Results from an 25 regional climate model simulations from the Coordinated Regional Downscaling Experiment (CORDEX) Africa initiative are used to assess the projected changes in temperature and precipitation over southern Africa at two Global Warming Levels (GWL), namely 1.5°C and 2.0°C, relative to preindustrial values, under the Representative Concentration Pathway 8.5. The results show a robust increase in temperature compared to the control period (1971-2000) ranging from 0.5 to 1.5°C for the 1.5°C GWL and from 1.5 to 2.5°C, for the 2.0°C GWL. Areas in the southwestern region of the subcontinent, covering South Africa and parts of Namibia and Botswana are projected to experience the largest increase in temperature, which are greater than the lobal mean warming, particularly during the September-October-November season. On the other hand, under 1.5°C GWL, models exhibit a robust reduction in precipitation of up to 0.4 mm/day (roughly 20% of the climatological values) over the Limpopo Basin and smaller areas of the Zambezi Basin in Zambia, and also parts of Western Cape, South Africa. Models project precipitation increase of up to 0.1 mm/day over central and western South Africa and in southern Namibia. Under 2.0°C GWL, a larger fraction of land is projected to face robust decreases between 0.2 and 0.4 mm/day (around 1020% of the climatological values) over most of the central subcontinent and parts of western South Africa and northern Mozambique. Decreases in precipitation are accompanied by increases in the number of consecutive dry days and decreases in consecutive wet days over the region. The importance of achieving the Paris Agreement is imperative for southern Africa as the projected changes under both the 1.5°C, and more so, 2.0°C GWL imply significant potential risks to agricultural and economic productivity, human and ecological systems health and water resources with implied increase in regional water stresses.