Here’s a new study for your “Boy, Are We In Trouble” file.   We’ve written a lot here about likely climate change effects like wildfires, rising seas, and water shortages, but one Pandora’s box we haven’t opened yet is the potential for a food crisis.  As it turns out, we may be in for a big one.

A Stanford study published in the January 9th issue of Science finds that rising temperatures are likely to have a major effect on crop yields in the the tropics and subtropics by 2100.  In some areas, the study predicts that primary food crops like maize and rice will be reduced by 20-to-40%.  Considering that half of the world’s population lives in these regions — three billion and rapidly growing — and that a large percentage are subsistence farmers, crop shortages could be devastating–and reverberate well beyond those regions, generating waves of “hunger refugees.”

Using 23 global climate models that contributed to the 2007 IPCC report, researchers from Stanford and the University of Washington determined that:

“There is a greater than 90% probability that by 2100 the lowest growing-season temperatures in the tropics and subtropics will be higher than any temperature recorded there to date.”

The researchers, Rosamond Naylor, director of Stanford University’s Program on Food Security and David Battisti, a University of Washington atmospheric sciences professor, looked at historic examples of food shortages caused by heat waves, such as France in 2003 and the Ukraine in 1972.

“I think that what startled me the most is that when we looked at our historic examples there were ways to address the problem within a given year,” said Naylor.  “People could always turn somewhere else to find food but in the future, there’s not going to be any place to turn unless we rethink our food supplies.”

The researchers say that the world must start planning adaptation strategies for what appears to be a likely scenario. And we might add that it’s not just the tropics at issue. If one of the nastier scenarios plays out for California’s snowpack and runoff, the resulting water crisis could also cripple food production right here, in one of the most productive and diverse agricultural regions in the world. In the grip of a three-year drought, the coming summer may give us a glimpse of things to come.