The Associated Press
Monday, August 9, 2010; 10:28 PM

MANILA, Philippines -- A projected rise in temperatures because of climate change will slow the growth of rice production in Asia, an international team of scientists says in a new study.

The study published Monday in the peer-reviewed journal of the U.S.-based National Academy of Sciences builds on previous findings that rising temperatures during the last 25 years have already cut the rice yield growth rate by 10 percent to 20 percent in several parts of Asia.

A decline in rice production means that more people will slip into poverty and hunger, the researchers said.

Around 3 billion people eat rice every day, and more than 60 percent of the world's 1 billion poorest and undernourished people who live in Asia depend on rice as their staple, according to the Philippine-based International Rice Research Institute.

Higher daytime temperatures can increase rice yields, but higher nighttime temperatures have a negative effect. The nighttime temperatures are rising faster and will cause a net loss in productivity, said Jarrod Welch, lead author and graduate student of economics at the University of California, San Diego.

"If we cannot change our rice production methods or develop new rice strains that can withstand higher temperatures, there will be a loss in rice production over the next few decades as days and nights get hotter," Welch wrote in the study. "This will get increasingly worse as temperatures rise further towards the middle of the century."

Scientists believe global greenhouse gas emissions must be cut in half by mid-century to keep the Earth's average temperature from rising more than 2 degrees Celsius (3.6 degrees Fahrenheit) above the levels that existed before nations began industrializing in the late 18th century.

Welch said the study that analyzed six years of data from 227 irrigated rice farms was the first of its kind because it used "real-world conditions" in addition to previous findings from controlled experiments.

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Online:

http://www.pnas.org/content/early/2010/07/26/1001222107.full.pdf+html © ;2010 ;The Associated Press
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