Intensification of the hydrological cycle expected in West Africa over the 21st century

Abstract

This study uses the high-resolution outputs of the recent CORDEX-Africa climate projections to investigate the future changes in different aspects of the hydrological cycle over West Africa. Over the twentyfirst century, temperatures in West Africa are expected to increase at a faster rate (C0:5 C per decade) than the global average (C0:3 C per decade), and mean precipitation is expected to increase over the Guinea Coast (C0:03mmd1 per decade) but decrease over the Sahel (0:005mmd1 per decade). In addition, precipitation is expected to become more intense (C0:2mmd1 per decade) and less frequent (1:5 d per decade) over all of West Africa as a result of increasing regional temperature (precipitation intensity increases on average by C0:35mmd1 C1 and precipitation frequency decreases on average by 2:2 d C1). Over the Sahel, the average length of dry spells is also expected to increase with temperature (C4%d C1), which increases the likelihood for droughts with warming in this subregion. Hence, the hydrological cycle is expected to increase throughout the twenty-first century over all of West Africa, on average by C11%C1 over the Sahel as a result of increasing precipitation intensity and lengthening of dry spells, and on average by C3%C1 over the Guinea Coast as a result of increasing precipitation intensity only.