How will world food supply be affected by climate change?

In 2007, drought struck the bread baskets of Europe, Russia, Canada, and Australia. Global grain stocks were already scant, so wheat prices began to rise rapidly. When countries put up trade barriers to keep their own harvests from being exported, prices doubled, according to an index of the Food and Agriculture Organization of the United Nations. Just 3 years later, another spike in food prices contributed to the Arab Spring uprisings.
Such weather-related crop disasters will become more likely with climate change, warns a detailed report released today by the Global Food Security (GFS) program, a network of public research funding agencies in the United Kingdom. “The risks are serious and should be a cause for concern,” writes David King, the U.K. Foreign Secretary’s Special Representative for Climate Change, in a foreword to the report.

To create the lengthy evaluation, dozens of scientists, policy wonks, and industry experts examined the global food system and its vulnerabilities to severe weather. They created a “plausible” worst case scenario: drought hitting four key staples—wheat, rice, corn, and soybeans—simultaneously. (The worrying precedents are a drought in 1988 to 1989 that cut yields of corn by an estimated 12% worldwide and soybeans by 8.5%, and a 2002 to 2003 drought that afflicted wheat and rice to a lesser extent.) If such a calamity struck next year, it would likely cause the price of grain to triple, the researchers suggest.
The chance of major global crop failures of this magnitude will increase with climate change, as drought, flooding, and heat waves strike fields more often. To estimate the odds, the researchers turned to existing models of how crops respond to temperature, precipitation, and other factors. By 2040, severe crop failures previously estimated to occur once a century are likely to happen every 3 decades, the report finds. The researchers emphasize that the risk analysis is preliminary. The report also highlights recent research indicating that the ever larger volumes of globally traded food raise the risk of large price shocks. Biofuel mandates, in which corn and other crops are turned into fuel, are thought to exacerbate the problem by cutting grain surpluses.