Drought and extreme heat slashed global cereal harvests between 1964 and 2007, and the impact of these weather disasters was greatest in North America, Europe and Australasia, according to a new study.
"We have always known that extreme weather causes crop production losses," said senior author Navin Ramankutty of University of British Columbia's Liu Institute for Global Issues and the Institute for Resources, Environment and Sustainability.
"But until now we did not know exactly how much global production was lost to such extreme weather events, and how they varied by different regions of the world," he added.
Ramankutty was part of a team consisting Canada's UBC and McGill University researchers, which analysed national production data from the UN's Food and Agriculture Organisation for 16 cereals in 177 countries.
Findings indicated that cereal harvests decreased by nine percent to 10 percent on average due to droughts and extreme heat. The impact from droughts also grew larger in more recent years.
Production levels in North America, Europe and Australasia dropped by an average of 19.9 percent because of droughts - roughly double the global average.
"Across the breadbaskets of North America, the crops and methods of farming are very uniform across huge areas, so if a drought hits in a way that is damaging to those crops, they will all suffer," said first author Corey Lesk, a graduate of McGill's department of Geography.
"By contrast, in much of the developing world, crop systems are a patchwork of small fields with diverse crops. If a drought hits, some of those crops may be damaged, but others may survive," Lesk added.
The analysis, however, reveal a bright side -- the extreme weather events had no significant lasting impact on agricultural production in the years following the disasters.
"Our findings may help guide agricultural priorities and adaptation efforts, to better protect the most vulnerable farming systems and the populations that depend on them," Ramankutty said.
The study was published in the latest issue of the journal Nature.
