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Climate and agriculture

Climate has a strong influence on agricultural production, considered as the most weather-dependent of all human activities, with socio-economical impacts whose severity varies from one region to another. These impacts are particularly strong in developing countries in the tropics that in many cases are exposed to high variability in climate, such as the monsoon system in India and in West Africa, the ENSO phenomenon in South-America, and where poverty increases the risk and the impact of natural disasters. This is especially true in the Sahel where rainfed crop production is the main source of food and income and where means to control the crop environment are largely unavailable to farmers: irrigation is rarely an option and use of mechanization, fertilizers, and other off-farm inputs is low. Considering the potential benefits of climate predictions to agriculture in the Sahel, it appears crucial to orient the research efforts to multidisciplinary studies such as the ones driven in the AMMA project (African Monsoon Multidisciplinary Analysis). These benefits can be achieved by communicating climate information to famers, monitoring and forecasting the crop yield, proposinginsurances based on weather based indices.

Rainfall and cereal yield in Niger

Rainfall and cereal yield in Niger
Rainfall and cereal yield in Niger
Rainfall (bars) are seasonal amounts from march to october provided by Agrhymet. National yields are provided by FAO. Those two variables are shown as standardised anomalies over the 1950-1990 period for rainfall and 1960-1990 period for yield. Positive (negative) rainfall anomalies are represented in blue (yellow).

Because of this strong influence of climate, global warming may thus have profound effects on agriculture and food security. Agriculture will also contribute to climate change as it plays a role in the climate system on a regional or a global scale by altering carbon and water budgets, and affecting surface energy balance. The last predictions concerning the potential impact of climate change on agriculture (see the report of the second IPCC working group ) indicate an increase of the productivity in the mid and high latitudes (due to increased photosynthesis with more CO2, longer growing periods and extension of frost-free growing regions) and a decrease of productivity in tropical and subtropical regions (drought, high temperatures). However there remains much uncertainty around these predictions due to our limited knowledge of the physiological processes of the plant and their spatial extrapolation, a weak representation of rainfall and cloud cover in climate models, difficulties of such models to give a regional and local response of climate change and uncertainties in socio-economic variables such as adaptability (new varieties, modification of the current crop geopolitical balance, human population movements, etc...). This uncertainty could be reduced by creating a link between physical, ecological and societal sciences that are all necessary to study the impacts of climate change. This multidisciplinary link is the main goal of the GIS « Climate-Environment-Society » involving strongly IPSL.

Author : Benjamin Sultan
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