Future heat waves pose threat to global food supply
Heat waves could significantly reduce crop yields and threaten global food supply if climate change is not tackled and reversed – according to new research from the University of East Anglia.
A new study published in the journal Environmental Research Letters estimates for the first time the global effects of extreme temperatures and elevated levels of carbon dioxide (CO2) on the production of corn, wheat and soybean.
Earlier studies have found that climate change is projected to reduce corn yields globally by the end of the century under a 'business as usual' scenario for future emissions of greenhouse gases. However, this new study shows that the inclusion of the effects of heat waves, which have not been accounted for in previous modelling calculations, could double the losses of the crop.
Lead author of the study Delphine Deryng, from the Tyndall Centre for Climate Change Research at UEA, said: “Instances of extreme temperatures, brought about by a large increase in global mean temperature, can be detrimental to crops at any stage of their development, but in particular around anthesis—the flowering period of the plant.
“At this stage, extreme temperatures can lead to reduced pollen sterility and reduced seed set, greatly reducing the crop yield.”
The impacts on wheat and soybean are likely to be less profound, primarily because of the fertilisation effects that elevated levels of CO2 can have on these crops.
In plants, CO2 is central to the process of photosynthesis—the mechanism by which they create food from sunlight, CO2 and water. When there is more CO2 in the atmosphere, the leaves of plants can capture more of it, resulting in an overall increase in the biomass of the plant.
In addition, plants are able to manage their water use much more efficiently in these conditions, resulting in better tolerance to drought episodes. However, it is not clear whether these CO2 fertilization effects will actually occur in the field owing to interactions with other factors.
If the CO2 fertilization effects do occur, the researchers found that the yields of wheat and soybean are expected to increase throughout the 21st century under a “business-as-usual” scenario. But the increases are projected to be significantly offset by the effects of heat waves, as these plants are still vulnerable to the effects of extreme temperatures.
The positive impacts on soybean yield will be offset by 25 percent and the positive impacts on wheat will be offset by 52 per cent.
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