Philippe Roudier

Assessing climate change impacts on sorghum and millet yields in the Sudanian and Sahelian savannas of West Africa

Sub-Saharan West Africa is a vulnerable region where a better quantification and understanding of the impact of climate change on crop yields is urgently needed. Here, we have applied the process-based crop model SARRA-H calibrated and validated over multi-year field trials and surveys at eight contrasting sites in terms of climate and agricultural practices in Senegal, Mali, Burkina Faso and Niger. The model gives a reasonable correlation with observed yields of sorghum and millet under a range of cultivars and traditional crop management practices. We applied the model to more than 7000 simulations of yields of sorghum and millet for 35 stations across West Africa and under very different future climate conditions. We took into account 35 possible climate scenarios by combining precipitation anomalies from 20% to 20% and temperature anomalies fromC0 toC6 C. We found that most of the 35 scenarios (31/35) showed a negative impact on yields, up to 41% forC6 C= 20% rainfall. Moreover, the potential future climate impacts on yields are very different from those recorded in the recent past. This is because of the increasingly adverse role of higher temperatures in reducing crop yields, irrespective of rainfall changes. When warming exceedsC2 C, negative impacts caused by temperature rise cannot be counteracted by any rainfall change. The probability of a yield reduction appears to be greater in the Sudanian region (southern Senegal, Mali, Burkina Faso, northern Togo and Benin), because of an exacerbated sensitivity to temperature changes compared to the Sahelian region (Niger, Mali, northern parts of Senegal and Burkina Faso), where crop yields are more sensitive to rainfall change. Finally, our simulations show that the photoperiod-sensitive traditional cultivars of millet and sorghum used by local farmers for centuries seem more resilient to future climate conditions than modern cultivars bred for their high yield potential ( 28% versus 40% for theC4 C= 20% scenario). Photoperiod-sensitive cultivars counteract the effect of temperature increase on shortening cultivar duration and thus would likely avoid the need to shift to cultivars with a greater thermal time requirement. However, given the large difference in mean yields of the modern versus traditional varieties, the modern varieties would still yield more under optimal fertility conditions in a warmer world, even if they are more affected by climate change.

La question de la vulnérabilité et de l'adaptation de l'agriculture sahélienne au climat au sein du programme AMMA

Rural populations in Soudano-Sahelian Africa are known to be particularly vulnerable to climate change due to a combination of naturally high levels of climate variability, high reliance on climate sensitive activities such as rain-fed agriculture and limited economic and institutional capacity to cope with and adapt to climate variability and change. Urgent actions are required to tackle the issues raised by climate change in Soudano-Sahelian Africa and these actions need to be supported by the best knowledge available. The AMMA program is attempting to revitalize research in Africa in this field through an integrated interdisciplinary framework that aims to increase our understanding of the problem and support decision making for the future.The first phase of AMMA tackled three major issues: (i) increase our understanding of the relationships between climate and agriculture (ii) quantify the vulnerability of agriculture productivity to climate change and (iii) explore pathways to cope with climate variability and change. This synthesis will show results from the first phase of the AMMA program to illustrate progress in each of these three issues.

Les bénéfices de la prévision saisonnière pour l’agriculture en Afrique de l’Ouest

The advantages of seasonal forecasting for West African agriculture The future of sub-Saharan Africa depends on the capability of the agricultural sector to guarantee food security for the vast majority of the population while the rapid growth Benjamin Sultan Philippe Roudier Philippe Quirion 1 Universit e Pierre et Marie Curie IRD LOCEAN/IPSL 4, place Jussieu 75252 Paris cedex 05 France <Benjamin.sultan@locean-ipsl.upmc.fr> 2 CNRS Cired Nogent-sur-Marne cedex Campus du Jardin Tropical 45 bis, avenue de la Belle Gabrielle 94736 Nogent-sur-Marne cedex France <roudier@centre-cired.fr> <quirion@centre-cired.fr> Pour citer cet article : Sultan B, Roudier P, Quirion P, 2013. Les b en efices de la pr evision saisonni ere pour l’agriculture en Afrique de l’Ouest. S echeresse 24 : 304-13. doi : 10.1684/sec.2013.0398 Tir es a part : B. Sultan d o i: 10684/se c.23.0398 304 S echeresse vol. 24, n8 4, octobre-novembre-d ecembre 2013 Article de recherche S echeresse 2013 ; 24 : 304–13