Projected expansion of hottest climate zones over Africa during the mid and late 21st century

Abstract

Projected shifts in thermal climate zones over Africa during the mid and late 21st century are assessed by employing the Thornthwaite thermal classification applied to 40 CMIP6 global climate models under the SSP1-2.6, SSP2-4.5 and SSP5-8.5 forcing scenarios. The CMIP6 multimodel ensemble mean reproduces the observed pattern of thermal zones during the reference period, albeit with some discrepancies. The projections reveal a gradual expansion of the hottest thermal type consisting of a northward and southward displacement of torrid climate zones, with this effect intensifying as greenhouse gas (GHG) forcing increases and the time horizon moves from the mid to the end of the century. In particular, the Mediterranean region, almost all southern African countries, part of East Africa and most Madagascar predominantly warm in present-day conditions, are projected to face mostly hot climates in the mid—21st century and torrid by the end of the 21st century in the high-end forcing scenario. Generally, in the mid—21st century, torrid climates expand by up to ∼15%, 20% and 27% of total Africa’s land areas for the SSP1-2.6, SSP2-4.5 and SSP5-8.5, respectively, with these fractions increasing to ∼16%, 28% and 42% in the late 21st century. Therefore, at the end of the 21st century for the high-end GHG concentration scenario, the African continent will be covered by 81%–87% of torrid climate type, which will have enormous impacts on the sustainable development of African countries.