Lesk, C. January 7, 2016. Influence of extreme weather disasters on global crop production. Nature.  

Drought and extreme heat events slashed cereal harvests in recent decades by 9% to 10% on average in affected countries with the greatest impact in North America, Europe, and Australasia.
The impact from droughts grew larger in the period from 1985 to 2007.

“We have always known that extreme weather causes crop production losses,” said senior author Navin Ramankutty, professor of global food security and sustainability at UBC’s Liu Institute for Global Issues and 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.”

Production levels in the more technically advanced agricultural systems of North America, Europe, and Australasia dropped by an average of 19.9% because of droughts – roughly double the global average.

“Across the breadbaskets of North America, for example, 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,” says first author Corey Lesk, a recent graduate of McGill’s Department of Geography. “By contrast, in much of the developing world, the cropping 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.

Annie Lowrey. 25 Jul 2012. Severe Drought Seen as Driving Cost of Food Up.  New York Times.

Scorching heat and the worst drought in nearly a half-century are threatening to send food prices up, spooking consumers and leading to worries about global food costs.