S ub -S aharan A frica : F ood P roduction at R isk
Figure 3.6: Multi-model mean of the percentage change in annual (top), austral summer (DJF-middle) and austral winter (JJAbottom) precipitation for RCP2.6 (left) and RCP8.5 (right) for Sub-Saharan Africa by 2071–99 relative to 1951–80
Hatched areas indicate uncertainty regions with two out of five models disagreeing on the direction of change compared to the remaining three models.
a sub-regional scale, these models show areas of strongly reduced precipitation by mid-century for a roughly 2°C global warming, for example in Uganda and Ethiopia (Patricola and Cook 2010; Cook and Vizy 2013; Laprise et al. 2013). Cook and Vizy (2012) showed how the strong decrease of the long rains in regional climate models, combined with warming, would lead to a drastically shorter growing season in East Africa, partly compensated by a modest increase in short-rains season length. Using global-model projections in precipitation, (Dai, 2012) estimated for a global-mean warming of 3°C by the end of the 21st century that drought risk expressed by the Palmer Drought
Severity Index25 (PDSI) reaches a permanent state of severe to extreme droughts in terms of present-day conditions over southern Africa, as well as increased drought risk over Central Africa. Dai (2012) showed that projected changes in soil-moisture content are generally consistent with the pattern of PDSI over SubSaharan Africa. Taylor et al. (2012) confirmed that the projected
25 Drought indicators like PDSI include a time-dependent water balance calculation
that includes monthly precipitation, temperature, wind speed, incoming radiation, and takes account of present-day local climate so that drought risk is presented relative to existing conditions.
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