Global warming and African climate change: a reassessment.

Keywords African climate; the Sahel; climate change; scenarios; climate variability Abstarct Understanding and predicting temporal variations in African climate has become the major challenge facing African and African-specialist climate scientists in recent years. Whilst seasonal climate forecasts have taken great strides forward, we remain unsure of the ultimate causes of the lower frequency decadal and multi-decadal rainfall variability that affects some African climate regimes, especially in the Sahel region. This work examining the variability of African climate, especially rainfall, is set in the wider context of our emerging understanding of human influences on the larger, global-scale climate. Africa will be no exception to experiencing these human-induced changes in climate, although much work remains to be done in trying to isolate those aspects of African climate variability that are ‘natural’ from those that are related to human influences. African climate scientists face a further challenge in that it is in this continent that the role of land-cover changes in modifying regional climates is perhaps most marked. It is for these reasons – large internal climate variability and the confounding role of land-cover change – that climate change ‘predictions’ (or scenarios) for Africa based on greenhouse gas warming remain at a low level of confidence. Nevertheless, it is of considerable interest to try and scope the magnitude of the problem that the enhanced greenhouse effect may pose for African climate and for African resource managers.