Rice at Risk: More Heat, Less Production

Wednesday, August 11, 2010 @ 05:08 PM gHale

Production of rice—the world’s most important crop for ensuring food security and addressing poverty—will decline as temperatures increase in rice-growing areas.
Evidence shows the net impact of projected temperature increases will slow the growth of rice production in Asia, according to a new study by an international team of scientists. Rising temperatures during the past 25 years have already cut the yield growth rate by 10% in several locations.
As nights get hotter, as predicted with climate change, rice yields will drop.
The report analyzed six years of data from 227 irrigated rice farms in 6 major rice-growing countries in Asia, which produces more than 90% of the world’s rice.
“We found that as the daily minimum temperature increases, or as nights get hotter, rice yields drop,” said Jarrod Welch, lead author of the report and graduate student of economics at the University of California, San Diego.
This is the first study to assess the impact of daily maximum and minimum temperatures on irrigated rice production in farmer-managed rice fields in tropical and subtropical regions of Asia.
“Our study is unique because it uses data collected in farmers’ fields, under real-world conditions,” Welch said. “This is an important addition to what we already know from controlled experiments.”
“Farmers can be expected to adapt to changing conditions, so real-world circumstances, and therefore outcomes, might differ from those in controlled experimental settings,” he added.
Around three billion people eat rice every day, and more than 60% of the world’s one billion poorest and undernourished people who live in Asia depend on rice as their staple food, the researchers said.
“Up to a point, higher day-time temperatures can increase rice yield, but future yield losses caused by higher night-time temperatures will likely outweigh any such gains because temperatures are rising faster at night,” Welch said. “And if day-time temperatures get too high, they too start to restrict rice yields, causing an additional loss in production.”
If day-time temperatures get too high, they will also restrict rice yields.
“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. This will get increasingly worse as temperatures rise further towards the middle of the century,” he added.

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