Extreme heat shortens wheat growing season, reduces yield

A new study out of Stanford University finds extreme temperatures are cutting wheat yields by 20 to as much as 50 percent, a finding worse than previously estimated. FSE center fellow David Lobell and his colleagues used nine years of satellite measurements of wheat growth in northern India's breadbasket, the Indo-Gangetic Plains, to analyze rates of wheat ageing after exposure to temperatures higher than 34 degrees Celsius. 

Extreme heat beyond the plant's tolerance zone damages photosynthetic cells. This causes wheat to age faster, reducing the length of the growing season and the amount and size of the wheat grains. The team's crop models found that a two degree increase in temperatures would reduce the growing season by nine days, yielding 20 percent less wheat.

As the world's second-biggest crop, lost wheat yields may become a major threat to global food security. Especially given the projection that global yields need to rise 50 percent by 2050 to feed a growing, more affluent population. The results imply that warming presents an even greater challenge to wheat than previous studies estimated, and that the effectiveness of adaptations will depend on how well they reduce crop sensitivity to very hot days, particularly in areas of the world such as India already experiencing warming conditions.