1 of 2 | Chinese workers hang a giant advertisement for a Sichuan restaurant in Beijing on April 28, 2011. Soaring food and fuel prices are threatening to derail growth in Asian economies, according to a study by the Asian Development Bank. Skyrocketing food prices have helped propel China's inflation beyond official targets for the fourth time in as many months. UPI/Stephen Shaver | License Photo
WASHINGTON, May 6 (UPI) -- Global climate change has already taken a toll on the world's food production, driving up the price of food by as much as 20 percent, a new study indicates.
The study, published Thursday in the journal Science, examined how rising temperatures has affected the world's major food crops: corn, wheat, rice and soybeans.
To estimate the economic impact of the changes in crop yield, the researchers used models of commodity markets.
"We found that since 1980, the effects of climate change on crop yields have caused an increase of approximately 20 percent in global market prices," said Wolfram Schlenker, an economist at Columbia University and a co-author of the paper.
The researchers said that global wheat production was 5.5 percent lower than it would have been had the climate remained stable. While global corn production was lower by nearly 4 percent, global rice and soybean production weren't significantly affected.
Relative to what yields might have been with no global warming, Russia, India and France experienced the greatest drops in wheat production, the study shows. China and Brazil suffered the largest comparative losses in corn production.
But the United States, Canada and northern Mexico have so far, for the most part, dodged the impacts of climate change.
"It appears as if farmers in North America got a pass on the first round of global warming," said David Lobell, an assistant professor of environmental Earth system science at Stanford University and an author of the report, in a statement.
Based on the predicted rates of global temperature rise over the next two to three decades, however, Lobell said it is unlikely the United States will continue to remain unscathed.
"The climate science is still unclear about why summers in the Corn Belt haven't been warming. But most explanations suggest that warming in the future is just as likely there as elsewhere in the world," Lobell said.
The United States is the world's largest producer of soybeans and corn, accounting for about 40 percent of global production.
The study's release Thursday also comes as the U.N. Food and Agriculture Organization reported that global corn prices doubled from April 2010 to April 2011.
Lobell said the study shows that climate change is "not just about the future, but that it is affecting agriculture now." He suggested that more heat- and drought-tolerant crops be developed to withstand the changes.