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May 06, 2011

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Study: global warming hurting corn, wheat crops

May 6, 2011
Courtesy of Science
and World Science staff

O­ver the past 30 years, glob­al corn and wheat pro­duc­tion has fall­en 3 to 5 per­cent in re­sponse to a warm­ing glob­al cli­mate, a new study re­ports.

The drop-off, it adds, may be re­spon­si­ble for the six per­cent rise in food prices since 1980—a $60-billion-a-year jump in what con­sumers paid for food.

Wheat fields near Ash­ton, Ida­ho. O­ver the past 30 years, glob­al corn and wheat pro­duc­tion has fall­en 3 to 5 per­cent in re­sponse to a warm­ing glob­al cli­mate, a new study re­ports. (Im­age courtesy Ida­ho Dept. of Com­merce)
Da­vid Lo­bell of Stan­ford Un­ivers­ity in Cal­i­for­nia and col­leagues ana­lyzed his­tor­i­cal food pro­duc­tion and weath­er da­ta from around the world, be­tween 1980 and 2008. 

Ex­am­in­ing the four larg­est ag­ri­cul­tur­al com­mod­i­ties—corn, wheat, rice, and soy­bean­s—they found that glob­ally, corn and wheat pro­duc­tion has de­creased in re­sponse to cli­mate warm­ing; that of the oth­er two foods has­n’t.

The re­search­ers ar­rived at the con­clu­sion by cre­at­ing two mod­els, one which mim­icked ac­tu­al in­creases in cli­mate tem­per­a­tures and anoth­er which kept cli­mate tem­per­a­tures “frozen” to what they were in 1980. All oth­er vari­ables were kept the same in both mod­els. 

There’s a startling ex­cep­tion to the over­all trend, Lo­bell and col­leagues added: the Un­ited States is­n’t get­ting hot­ter, nor are its crops de­creas­ing, a dis­crep­an­cy in agri­cult­ural trends un­no­ticed be­fore now.

Sci­en­tists have been warn­ing with in­creas­ing ur­gen­cy of grad­u­ally ris­ing glob­al tem­per­a­tures, which they gen­er­ally blame on human-caused emis­sions of gas­es that trap heat in the at­mos­phere.

The find­ings on crops are pub­lished in the May 6 is­sue of the re­search jour­nal Sci­ence.

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Over the past 30 years, global corn and wheat production has fallen 3 to 5 percent in response to a warming global climate, a new study reports. The drop-off, it adds, may be responsible for the six percent rise in food prices since 1980—a $60-billion-a-year jump in what consumers paid for food. David Lobell of Stanford University in California and colleagues examined historical food production and weather data from around the world, between 1980 and 2008. Examining the four largest agricultural commodities—corn, wheat, rice, and soybeans—they found globally, corn and wheat production has decreased in response to climate warming; that of the other two foods hasn’t. The researchers arrived at the conclusion by creating two models, one which mimicked actual increases in climate temperatures and another which kept climate temperatures “frozen” to what they were in 1980 while ensuring all other variables stayed the same in both models. But there’s a startling exception to the data, Lobell and colleagues added: the United States isn’t getting hotter, nor are its crops decreasing, a discrepancy that went unnoticed before now. Scientists have been warning with increasing urgency of gradually rising global temperatures, which they generally blame on human-caused emissions of gases that trap heat in the atmosphere. The findings on crops are published in the May 6 issue of the research journal Science.