Possible influence of climate change on water balance over West Africa under the global warming levels of 2 and 3 °C

Abstract

Reliable projection of water balance components for the future over a climate change vulnerable region such as West Africa is exigent for proper adaptation strategies. This paper analyses the expected water balance in the 21st century over West Africa at 2 and 3 °C global warming level (GWL) based on Rossby Centre Regional Atmospheric Climate Model (RCA4) downscaled projections. Precipitation is expected to increase at the south-western (−5 to 10°N, 15 to 25°W) ocean area of West Africa domain with SW–NE orientation, towards the Sahel, while other areas would be drier, at 2 °C GWL. This would intensify under 3 °C GWL. Responses of evapotranspiration and storage change are similar to that of precipitation except for more spatial spread of increased evapotranspiration on the ocean. Runoff would increase over the ocean, Sahara and part of Sahel and reduce in Savannah and Guinea Coast under 2 °C GWL, but reduce under a warmer world with isolated increase. HIGHLIGHTS Precipitation would increase during AMJJAS from the Atlantic Ocean to the Sahel with SW-NE orientation under 2 °C Global Warming Level (GWL).; Wetness along SW-NE would intensify with increasing GWL.; Evapotranspiration and storage change would increase with increasing GWL during AMJJAS.; Runoff would increase over the ocean and high latitudes, while it would reduce at the lower latitudes under 2 °C GWL during AMJJAS.;

Keywords

• evapotranspiration
• gwl
• rca4
• runoff
• storage change
• water balance