Climate Change Risks: Rainfall Patterns

So having established that climate change is not Africa's fault but it will be the most affected, we have to establish how it will be affected.

One of the major effects on Africa due to climate change will be alterations in precipitation regime. In his paper for Environment International on what we know about changing rainfall patterns Mohammed Dore observes:

'That wet areas become wetter, and dry and arid areas become more so. In addition, the following general changing pattern is emerging: (a) increased precipitation in high latitudes (Northern Hemisphere); (b) reductions in precipitation in China, Australia and the Small Island States in the Pacific; and (c) increased variance in equatorial regions.'

Applying this to Africa would mean increased variance over the majority, which has negative implications for water management, the tropical areas have higher rainfall and the drier have lower. In other words, the weather becomes more extreme. Allan et al. observes that in the 30% of wettest tropical areas rainfall will increase by 1.8%/decade, and in the driest 30% of tropical regions will decrease by 2.6%/decade (calculated using the GPCP with data from 1988-2008).

Unfortunately for dry or tropical regions (majority of SSA) rainfall decreasing 2.6%/decade does not mean water decreasing 2.6%/decade. De Wit and Stankiewicz studied what falling rainfall would mean for surface water in Africa, and it makes for fairly grim reading. Across Africa, a 10% fall in rainfall would reduce surface water by 17-50%. This nonlinear response is particularly worrying. The table below is an extract from their work, with Tulear, Mogadisu and Jenouba's perennial drainage all dropping to an alarming 0% of current levels with a 10% drop in precipitation.

De Wit and Stankiewicz