African climate change: 1900-2100

This paper reviews observed (1900-2000) and possible future (2000-2100) con tinent-wide changes in temperature and rainfall for Africa. For the histori c period we draw upon a new observed global climate data set which allows u s to explore aspects of regional climate change related to diurnal temperat ure range and rainfall variability. The latter includes an investigation of regions where seasonal rainfall is sensitive to El Nino climate variabilit y. This review of past climate change provides the context for our scenario s of future greenhouse gas-induced climate change in Africa. These scenario s draw upon the draft emissions scenarios prepared for the Intergovernmenta l Panel on Climate Change's Third Assessment Report, a suite of recent glob al climate model experiments, and a simple climate model to link these 2 se ts of analyses. We present a range of 4 climate futures for Africa, focusin g on changes in both continental and regional seasonal-mean temperature and rainfall. Estimates of associated changes in global CO2 concentration and global-mean sea-level change are also supplied. These scenarios draw upon s ome of the most recent climate modelling work. We also identify some fundam ental limitations to knowledge with regard to future African climate. These include the often poor representation of El Nino climate variability in gl obal climate models, and the absence in these models of any representation of regional changes in land cover and dust and biomass aerosol loadings. Th ese omitted processes may well have important consequences for future Afric an climates, especially at regional scales. We conclude by discussing the v alue of the sort of climate change scenarios presented here and how best th ey should be used in national and regional vulnerability and adaptation ass essments.