Modeling the potential impacts of vegetation change on the future climate of Southern Africa

Many studies have projected a future warming over Southern Africa without including the influence of on - going vegetation changes in the region. This study investigates how the vegetation changes may alter the projected warming. For the study, two regional climate models (RegCM and WRF) were applied to simulate the present day (1970 - 2005) and the future (2030 - 2065; IPCC RCP 4.5) climate, with and without vegetation change. The study considers two scenarios of vegetation change: the first accounts for the potential impacts of natural bush encroachment and commercial forestation in the eastern part of South Africa, while the second accounts for the expansion of grass cover along the western region of the Grassland Biome in South Africa. The result s of this study agree with that of previous studies in that elevated greenhouse emissions will induce warming over Southern Africa in the future , but further indicate that the ongoing vegetation change s may considerably alter the magnitude of the warming. Forestation may enhance the warming over the forested area and induce cooling elsewhere. It may also produce wet conditions locally and induce dry conditions over other area within the region. In contrast, the expansion of grass cover may reduce the projected warming over the grass covered area and induce warming elsewhere. It may also induce dry conditions locally and produce wet conditions over other areas in the sub-continent. Both vegetation change scenarios ( i.e. forestation and expansion of grass cover ) alter the projected future climate changes through their influence s on local surface albedo ; while forestation decreases the surface albedo, the expansion of grass cover increase s it . However, the changes in rainfall and temperature from the vegetation changes could enhance the frequency drought over some areas and reduce it over other areas with in Southern Africa. This study, therefore, suggests that the vegetation changes may produce unexpected impacts on future climate. It also suggests that before using vegetation changes to mitigate climate change in Southern Africa, the biogeochemical benefits (i.e. carbon sequestration) should be carefully weighed against biogeophysical effects (i.e. changes in albedo)