The production of rice, wheat and corn, very greedy in water, could drop by nearly 20% with the rise in temperatures linked to climate change, says a report by the International Fund for Agricultural Development (IFAD), published at the eve of COP26. Episodes of extreme heat may be more frequent, leading to water stress and increased plant transpiration. At the same time, the concentration of CO2 in the air, which drives photosynthesis, should boost plant growth by 10-20%, but “the positive effects will not however be able to counterbalance the losses due to the heat”, notes Edward Gérardeaux, main author of the report.
Among the main risks for agriculture are “increased damage from pests, diseases and floods to food systems infrastructure”. The main cereal crops in Africa will be affected.
“Under the most pessimistic climate change scenario, the average yield would decrease by 13% in West and Central Africa, 11% in North Africa and 8% in East and Southern Africa. Millet and sorghum are the crops most resistant to heat stress, with yield loss by 2050 limited to 5% and 8%, while rice and wheat are expected to be the worst-hit crops, with loss yield by 2050 estimated at 12% and 21%, respectively “, specifies the document.
However, the report underlines that a few rare regions could benefit from it: “In some high-altitude areas, the cold is currently a limiting factor for crops. Madagascar, for example, could see its rice production in the highlands increase thanks to the heat.” While the south of the country is currently experiencing a dramatic drought and famine.
Fida recommends crop diversification, reducing dependence on maize in favor of cassava, peanuts, beans, sorghum and millet. Still according to the Fida report,“radical changes in the choice of crops and local agricultural practices will be necessary”.
Another study, published in August 2021 in Agronomy for Sustainable Development, confirms a probable decrease in Senegalese rainfed rice production. The authors of the study encourage varietal adaptation, which consists of choosing rice varieties that are more resistant to heat and more efficient in water.
Experts also recommend the adoption of agro-ecological intensification techniques: soil mulching to limit evaporation, agroforestry to increase shade and reduce wind, or even associated crops to reduce risks and optimize the use of soil resources. A hope, since the possible yield gains with agroecological intensification could partially offset the losses linked to climate change.