Climate Change Increases Future Global Wheat Yield Variability and Warming Exhibited Greater Contribution than Precipitation Change

Climate change could substantially alter yield distribution, and exerts critical impacts on food availability and stability. Previous studies have intensively assessed climate change impact on crop mean yield and therefore food availability, but climate change impact on crop yield variability and consequently food supply stability remains largely under-addressed. In this study, we conducted a multi-model ensemble simulation by developing emulators of global gridded crop models to evaluate global wheat yield variability (coefficient of variation, CV) change relative to baseline (1986-2005) under 2 representative concentration pathways (RCP4.5 and RCP8.5). We also separated the relative contribution of temperature and precipitation changes to wheat yield variability change by using control group simulation experiments. The results of multi model ensemble across 3 emulators and 21 general circulation models indicated that yield variability would increase in two thirds of global wheat harvested areas. There would be over 20% of the harvested areas experiencing sharp yield variability increase (CV change >10%). Eight out of top 10 wheat producing countries would have greater yield variability than the baseline period, and the largest increase would occur in India (12.0%) and Australia (7.8%). After separation, warming exhibits greater contribution than precipitation change in 68% global harvested area, and 15% of the pixels that are projected to experience sharp yield variability increase. In addition, yield variability increasing in six out of the top 10 wheat producing countries could be mainly attributed to warming, which indicated the importance of alleviating the heat stress under future climate change. However, in some countries, like Australia, adjusting irrigation strategies and equipment is critical for adapting precipitation change. Our research highlighted the serious challenge of increased yield variability in fostering global food resilience under climate change, and called for urgent consideration of yield instability in risk governance and adaptation strategies.