Projections of rapidly rising surface temperatures over Africa under low mitigation

Abstract

An analysis of observed trends in African annual-average near-surface temperatures over the last five
\ndecades reveals drastic increases, particularly over parts of the subtropics and central tropical Africa.
\nOver these regions, temperatures have been rising at more than twice the global rate of temperature
\nincrease. An ensemble of high-resolution downscalings, obtained using a single regional climate
\nmodel forced with the sea-surface temperatures and sea-ice fields of an ensemble of global circulation
\nmodel (GCM) simulations, is shown to realistically represent the relatively strong temperature
\nincreases observed in subtropical southern and northern Africa. The amplitudes of warming are
\ngenerally underestimated, however. Further warming is projected to occur during the 21st century,
\nwith plausible increases of 4–6 °Cover the subtropics and 3–5 °Cover the tropics by the end of the
\ncentury relative to present-day climate under the A2 (a low mitigation) scenario of the Special Report
\non Emission Scenarios. High impact climate events such as heat-wave days and high fire-danger days
\nare consistently projected to increase drastically in their frequency of occurrence. General decreases in
\nsoil-moisture availability are projected, even for regions where increases in rainfall are plausible, due
\nto enhanced levels of evaporation. The regional dowscalings presented here, and recentGCM
\nprojections obtained for Africa, indicate that African annual-averaged temperatures may plausibly rise
\nat about 1.5 times the global rate of temperature increase in the subtropics, and at a somewhat lower
\nrate in the tropics. These projected increases although drastic, may be conservative given the model
\nunderestimations of observed temperature trends. The relatively strong rate of warming over Africa,
\nin combination with the associated increases in extreme temperature events, may be key factors to
\nconsider when interpreting the suitability of global mitigation targets in terms of African climate
\nchange and climate change adaptation in Africa