Climate Change: Huge Wheat Yield Drop in Africa and South Asia
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Leading crop simulation models used by a global team of agricultural scientists to simulate Wheat production up to 2050 showed significant Wheat yield reductions due to climate change in Africa and South Asia, where food security is already a problem. Africa and South Asia are significant Wheat importers because of their limited Wheat production. For instance, Bangladesh imported Wheat for almost $2 billion in 2021. According to the AgFlow data, Bangladesh imported 1.7 million tons of Wheat in Jan-May 2023. In May, key suppliers were Romania (116,500 tons), Russia (109,242 tons), and Australia (50,000 tons).
The model predicted average declines in Wheat yields of 15% in African countries and 16% in South Asian countries by mid-century, as described in the 2021 paper “Climate impact and adaptation to heat and drought stress of regional and global Wheat production,” published in the science journal Environmental Research Letters. According to the research, climate change will lower global Wheat production by 1.9% by mid-century, with the most negative impacts occurring in Africa and South Asia.
“Studies have already shown that Wheat yields fell by 5.5% during 1980-2010 due to rising global temperatures,” said Diego N.L. Pequeno, Wheat crop modeler at the International Maize and Wheat Improvement Center (CIMMYT) and lead author of the paper. “We chose several models to simulate climate change impacts and also simulated Wheat varieties that featured increased heat tolerance, early vigor against late-season drought, and late flowering to ensure normal biomass accumulation. Finally, we simulated using an additional nitrogen fertilizer to maximize the expression of these adaptive traits.”
Several factors, including temperature, water deficit, and water access, have been identified as significant causes of worldwide Wheat yield variability. The DSSAT Wheat models simulate the impact of temperature, including heat stress, water balance, drought stress, or nitrogen leaching from heavy rainfall. “Generally, small and low-volume Wheat producers suffered large negative impacts due to future climate changes, indicating that less developed countries may be the most affected,” Pequeno added.
“Our results showed that the adaptive traits could help alleviate climate change impacts on Wheat, but responses would vary widely, depending on the growing environment and management practices used,” said Pequeno. This implies that Wheat breeding for traits associated with climate resilience is a promising climate change adaptation option, but its effect will vary among regions. Its positive impact could be limited by agronomical aspects, particularly under rainfed and low soil N conditions, where water and nitrogen stress restrict the benefits of improved cultivars.
Extreme weather events could also become more frequent. Those were possibly underestimated in this study, as projections of heat damage effects considered only changes in daily absolute temperatures but not possible changes in the frequency of occurrence. Another limitation is that most crop models lack functions for simulating excess water (e.g., flooding), a significant cause of global Wheat yield variability.
At lower latitudes that are close to the tropics, already warm, and experiencing insufficient rainfall for food crops and therefore depending on irrigation (North India, Pakistan, Bangladesh), rising heat will damage Wheat crops and seriously reduce yields. China, the largest Wheat producer in the world, is projected to have mixed impacts from climate change, but at a nationwide scale, the study showed a 1.2% increase in Wheat yields.
Positive Impacts at High Latitudes: France and Germany
Climate change at high latitudes (France, Germany, and northern China, all large Wheat-producing countries/regions) positively impacted Wheat grain yield, as warming temperatures benefit Wheat growth through an extended early spring growing season. But warmer temperatures and insufficient rainfall by mid-century, as projected at the same latitude in Russia and the northwestern United States, will reduce rainfed Wheat yields — a finding that contradicts outcomes of some previous studies.
Other sources: CIMMYT
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