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

Stella Todzo , Adeline Bichet , Arona Diedhiou (1)

1 IGE - Institut des Géosciences de l’Environnement

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 twenty-first century, temperatures in West Africa are expected to increase at a faster rate (+0.5 ^∘C per decade) than the global average (+0.3 ^∘C per decade), and mean precipitation is expected to increase over the Guinea Coast (+0.03 mm d^-1 per decade) but decrease over the Sahel (-0.005 mm d^-1 per decade). In addition, precipitation is expected to become more intense (+0.2 mm d^-1 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 +0.35 mm d^{-1 ∘}C^-1 and precipitation frequency decreases on average by -2.2 d ^∘C^-1). Over the Sahel, the average length of dry spells is also expected to increase with temperature (+4 % d ^∘C^-1), 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 +11 % ^∘C^-1 over the Sahel as a result of increasing precipitation intensity and lengthening of dry spells, and on average by +3 % ^∘C^-1 over the Guinea Coast as a result of increasing precipitation intensity only.

Domaines: Planète et Univers [physics]

Stella Todzo, Adeline Bichet, Arona Diedhiou. Intensification of the hydrological cycle expected in West Africa over the 21st century. Earth System Dynamics, 2020, 11, pp.319-328. ⟨10.5194/esd-11-319-2020⟩. ⟨insu-03706470⟩