Projected changes in crop yield mean and variability over West Africa in a world 1.5 K warmer than the pre-industrial era

Abstract

Abstract. The ability of a region to feed itself in the upcoming decades is an important issue. The West African population is expected to increase significantly in the next 30 years. The responses of crops to short-term climate change is critical to the population and the decision makers tasked with food security. This leads to three questions: how will crop yields change in the near future? What influence will climate change have on crop failures? Which adaptation methods should be employed to ameliorate undesirable changes?An ensemble of near-term climate projections are used to simulate maize, millet and sorghum in West Africa in the recent historic period (1986)(1987)(1988)(1989)(1990)(1991)(1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005) and a near-term future when global temperatures are 1.5 K above preindustrial levels to assess the change in yield, yield variability and crop failure rate. Four crop models were used to simulate maize, millet and sorghum in West Africa in the historic and future climates.Across the majority of West Africa the maize, millet and sorghum yields are shown to fall. In the regions where yields increase, the variability also increases. This increase in variability increases the likelihood of crop failures, which are defined as yield negative anomalies beyond 1 standard deviation during the historic period. The increasing variability increases the frequency of crop failures across West Africa. The return time of crop failures falls from 8.8, 9.7 and 10.1 years to 5.2, 6.3 and 5.8 years for maize, millet and sorghum respectively.The adoption of heat-resistant cultivars and the use of captured rainwater have been investigated using one crop model as an idealized sensitivity test. The generalized doption of a cultivar resistant to high-temperature stress during flowering is shown to be more beneficial than using rainwater harvesting.

Global wheat production with 1.5 and 2.0°C above pre‐industrial warming

“…Despite mostly positive impacts on average yields, projections suggest that the frequency of extreme low yields will increase under both scenarios for some of the hot growing locations (for both low rainfall and irrigated sites), including India, that currently supply more than 14% of global wheat (FAO, 2014). Similarly, an increase in the frequency of crop failures has been shown with 1.5°C global warming above the pre-industrial period for maize, millet, and sorghum in West Africa (Parkes, Defrance, Sultan, Ciais, & Wang, 2018). On the other hand, Faye et al (2018) did not detect a change in yield variability for the same three crops in West African between the 1.5 and 2.0°C warming scenarios using HAPPI climate data.…”

Direct and indirect effects of CO2increase on crop yield in West Africa

“…The crop model is simulating potential yields, without calibration. The parameter set is the same as the one used in Parkes et al (2018), this includes the high-temperature stress routine. This routine reduces crop yields as a result of high-temperature stress during flowering.…”

“…These inputs are maximum daily temperature, minimum daily temperature, downwelling short-wave radiation at the surface and precipitation. The maize parameter set is identical to the one used in Parkes et al (2018) and based on the parameter set used in Vermeulen et al (2013). In this study GLAM was run with an idealized crop where the yield gap parameter is set to 1 instead of being calibrated to observed crop yields Parkes et al, 2015).…”

Assessing Future Spatio-Temporal Changes in Crop Suitability and Planting Season over West Africa: Using the Concept of Crop-Climate Departure

“…It is geographically located at latitude 4-20 • N and 16 • W-20 • E and has rainfed agriculture as its mainstay economy. The region can be divided into three Food and Agriculture Organization (FAO) agro ecological zones (AEZs) namely, Guinea (4-8 • N), Savanna (8)(9)(10)(11)(12) • N) and the Sahel (12)(13)(14)(15)(16)(17)(18)(19)(20) • N) [24,25]. The region also has some localized highlands (Cameroon Mountains, Jos Plateau, and Guinea Highlands) which influence its climate.…”

“…Agriculture is the most and major economic sector of Africa and has been described as the most vulnerable sector to the climate change impact with a great threat to the farming systems, crop production and food security at any level [7,[12][13][14]. For example, past studies e.g., [15][16][17][18][19] have shown the impact of climate change on crop production and yield in Africa and West Africa in particular using different crop models. Sultan et al [15] showed the decrease in the mean yield of sorghum cultivars due to the impact of climate change resulting from variation in the rainfall pattern and increasing temperature.…”