Response of climate extremes over Southern African Monsoon Region to
limiting global warming to 1.5℃ instead of 2℃
Already vulnerable monsoon regions like those in populous Africa are
expected to be hard-hit by the effects of anthropogenic global warming.
Therefore, such areas could benefit from low global warming levels.
Using the Community Earth System Model low-warming simulations, we study
the avoided impacts over the southern Africa monsoon region (SAMR) from
limiting warming to 1.5℃ instead of 2℃. There is a tendency of dryer and
significant warmer conditions being projected over SAMR at the
1.5℃warming world and is amplified at the 2℃warming world with warming
exceeding the mean global warming rates. Specifically, a change of 0.63℃
0.04℃ in surface temperature is projected from 1.5℃ to 2℃ warmer
world. Consequently, extreme climate events in the SAMR are also
estimated to respond to this warming albeit precipitation based extremes
showing higher uncertainty levels than temperature extremes. In
particular, there is a projected increase in severity of heatwaves and
the number of cumulative dry days accompanied by an increasing rainfall
intensity events from 1.5 to 2℃ warming in SAMR. This may have severe
implications for run-off characteristics in the region especially when
half of the land area here is being projected to have a 20% increase in
extreme precipitation. We also estimate an increase in cumulative dry
days in the SAMR where a decrease in rainfall is also expected with
warming. This may exacerbate drought occurrence in the region under a 2℃
warmer climate than under a 1.5℃ one. Restricting warming to 0.5℃ lower
than 2℃ is projected to result in 5 to 10 mm/day reductions in the
intensity of rainfall extremes across the SAMR. This restriction in
warming is also projected to lead to 29% (27-31%) to 42% (39-48%)
reduction in severity and frequency of high-temperature extreme events.
Once-in-10/20-year heat extremes may also be reduced by as much as 28%
(25-34%) to 37% (34-40%) from limiting warming to half a degree lower
than 2℃ in the region. Moreover, the probability of occurrence of the
record-breaking extreme drought experienced in summer of 1991/1992 in
southern Africa is projected to be reduced by about 20% 4% from
limiting warning to 1.5℃ instead of 2℃. This probability is heavily
linked to changes in temperature associated with that drought.
Therefore, restricting warming to low levels may indeed translate to
substantial benefits in the Southern Africa Monsoon region.