Robust features of future climate change impacts on sorghum yields in West Africa

Abstract

West Africa is highly vulnerable to climate hazards and better quantification and understanding of the impact of climate change on crop yields are urgently needed. Here we provide an assessment of near-term climate change impacts on sorghum yields in West Africa and account for uncertainties both in future climate scenarios and in crop models. Towards this goal, we use simulations of nine bias-corrected CMIP5 climate models and two crop models (SARRA-H and APSIM) to evaluate the robustness of projected crop yield impacts in this area. In broad agreement with the full CMIP5 ensemble, our subset of bias-corrected climate models projects a mean warming of +2.8°C in the decades of 2031-2060 compared to a baseline of 1961-1990 and a robust change in rainfall in West Africa with less rain in the Western part of the Sahel (Senegal, South-West Mali) and more rain in Central Sahel (Burkina Faso, South-West Niger). Projected rainfall deficits are concentrated in early monsoon season in the Western part of the Sahel while positive rainfall changes are found in late monsoon season all over the Sahel, suggesting a shift in the seasonality of the monsoon. In response to such climate change, but without accounting for direct crop responses to CO 2 , mean crop yield decreases by about 16-20% and year-to-year variability increases in the Western part of the Sahel, while the eastern domain sees much milder impacts. Such differences in climate and impacts projections between the Western and Eastern parts of the Sahel are highly consistent across the climate and crop models used in this study. We investigate the robustness of impacts for different choices of cultivars, nutrient treatments, and crop responses to CO 2 . Adverse impacts on mean yield and yield variability are lowest for modern cultivars, as their short and nearly fixed growth cycle appears to be more resilient to the seasonality shift of the monsoon, thus suggesting shorter season varieties could be considered a potential adaptation to ongoing climate changes. Easing nitrogen stress via increasing fertilizer inputs would increase absolute yields, but also make the crops more responsive to climate stresses, thus enhancing the negative impacts of climate change in a relative sense. Finally, CO 2 fertilization would significantly offset the negative climate Environmental Research Letters Environ.impacts on sorghum yields by about 10%, with drier regions experiencing the largest benefits, though the net impacts of climate change remain negative even after accounting for CO 2 .

Impacts of Climate Variability and Change on Rainfed Sorghum and Maize: Implications for Food Security Policy in Tanzania

“…This is consistent to results by Rosenzweig et al (2014) who reported model agreement on direction of yield change but varying in magnitude. Sultan et al (2014) observed high consistence across climate and crop models in climate and impacts projections on sorghum between the western and eastern parts of the Sahel. In East Africa, a study by Thornton et al (2009) similarly showed yield decreases for maize over the region ranging between 1% and 15% across emissions scenarios and climate models, largely as a result of temperature increase.…”

“…The influence of the improved agro-systems on crop sensitivity to climate change is still a matter of debate (Turner & Rao, 2013;Sultan et al, 2014). While on the one hand, Turner and Rao (2013) show minimum stress from warming temperatures under the current low-input production systems (no-N fertilizer added) compared to improved systems (with adequate N fertilization), Sultan et al (2014) show that increasing fertilizer inputs in the Sahel agricultural system could make it more responsive to climatic stresses and produce more negative impacts (in a relative sense, %) in crop yields under climate change. Results from both studies suggest that sorghum yields under current smallholders' low-input systems would be resilient or even increase under increasing temperatures.…”

Evolution of Surface Hydrology in the Sahelo-Sudanian Strip: An Updated Review

“…For the future, the IPCC 2013 [120] and IPCC 2017 [121] climate projections suggest an increase in rainfall in West Africa due to global warming, which would favor the dynamics of the monsoon, except in the western part of West Africa, where they suggest a dry period near the Atlantic Ocean in the near future (Biasutti [122] and Sultan [123]). However, the models are not accurate in their depiction of regional West African climates [124].…”

Disaggregating sorghum yield reductions under warming scenarios exposes narrow genetic diversity in US breeding programs

“…agriculture | climate change | crop | sorghum | warming S orghum (Sorghum bicolor) is predominantly grown in the arid and semiarid regions of the world, where heat stress is known to induce significant yield losses (1)(2)(3)(4). Globally, sorghum is positioned as the fifth most economically important cereal and plays a critical role in providing food, fodder, and fuel (5,6).…”