The small rainfall recovery observed over the Sahel, concomitant with a regional climate warming, conceals some drought features that exacerbate food security. The new rainfall features include false start and early cessation of rainy seasons, increased frequency of intense daily rainfall, increasing number of hot nights and warm days and a decreasing trend in diurnal temperature range. Here, we explain these mixed dry/wet seasonal rainfall features which are called hybrid rainy seasons by delving into observed data consensus on the reduction in rainfall amount, its spatial coverage, timing and erratic distribution of events, and other atmospheric variables crucial in agro-climatic monitoring and seasonal forecasting. Further composite investigations of seasonal droughts, oceans warming and the regional atmospheric circulation nexus reveal that the low-to-mid-level atmospheric winds pattern, often stationary relative to either strong or neutral El-Niño-Southern-Oscillations drought patterns, associates to basin warmings in the North Atlantic and the Mediterranean Sea to trigger hybrid rainy seasons in the Sahel. More challenging to rain-fed farming systems, our results suggest that these new rainfall conditions will most likely be sustained by global warming, reshaping thereby our understanding of food insecurity in this region.
Institute of Meteorology and Climate Research, Atmospheric Environmental Research (IMK-IFU), Karlsruhe Institute of Technology (KIT), Kreuzeckbahnstr. 19, D-82467 Garmisch-Partenkirchen, Germany;WASCAL Competence Center, West African Science Service Center on Climate Change and Adapted Land Use (WASCAL CoC), 06 BP: 9507 Ouagadougou, Burkina Faso;Institute of Meteorology and Climate Research, Atmospheric Environmental Research (IMK-IFU), Karlsruhe Institute of Technology (KIT), Kreuzeckbahnstr. 19, D-82467 Garmisch-Partenkirchen, Germany;Institute of Geography, Chair for Regional Climate and Hydrology, University of Augsburg, D-86135 Augsburg, Germany;International Research Institute for Climate and Society, The Earth Institute, Columbia University, PO Box 1000, Palisades, NY 10964-8000, USA;Département Formation et Recherche (DFR), Centre Régional AGRHYMET (CRA), BP 11011, 425 Boulevard de l’Université, Niamey, Niger;WASCAL Competence Center, West African Science Service Center on Climate Change and Adapted Land Use (WASCAL CoC), 06 BP: 9507 Ouagadougou, Burkina Faso;International Institute of Tropical Agriculture (IITA), Kano Research station, Sabo Bakin Zuwo Road, PMB 3112, Kano, Nigeria;Institute of Geography, Chair for Regional Climate and Hydrology, University of Augsburg, D-86135 Augsburg, Germany;Institute of Meteorology and Climate Research, Atmospheric Environmental Research (IMK-IFU), Karlsruhe Institute of Technology (KIT), Kreuzeckbahnstr. 19, D-82467 Garmisch-Partenkirchen, Germany;Institute of Geography, Chair for Regional Climate and Hydrology, University of Augsburg, D-86135 Augsburg, Germany
Recommended Citation:
Seyni Salack,Cornelia Klein,Alessandra Giannini,et al. Global warming induced hybrid rainy seasons in the Sahel[J]. Environmental Research Letters,2016-01-01,11(10)