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Production of wheat fell dramatically as a result of climate change in countries such as Brazil and Mexico.

Production of wheat fell dramatically as a result of climate change in countries such as Brazil and Mexico.

Science reports some bad news about the effect of planetary heating on agriculture:

[David Lobell, an agricultural scientist at Stanford University in Palo Alto, California] and colleagues analyzed agricultural records of corn, rice, wheat, and soybeans from 1980 to 2008. Those four crops make up 75% of the calories consumed by the world’s population. Using historical weather data on temperature and precipitation, the researchers constructed a trend line of weather patterns, controlling for a certain amount of seasonal variation, and linked it to crop data year by year. They also constructed a second trend line that assumed no warming during the period, and then compared the two.

Worldwide, the authors report … yields of corn and wheat declined by 3.8% and 5.5%, respectively, compared with what they would have been without global warming. Rice and soybean production remained the same. But the trends vary considerably from region to region. Unlike most other regions, the United States and Canada saw no climate-linked decline in food production during this period. Lobell says that this is consistent with data from the Intergovernmental Panel on Climate Change (IPCC) showing that the eastern part of the United States has not warmed as much as other parts of the world for unknown reasons.

The most surprising finding, Lobell says, was how widely temperature trends varied by region and how dramatically they affected crop production. Rainfall, by contrast, seemed to contribute little to agricultural production trends. Although new technology and better farming practices have led to an overall increase in productivity, Lobell says, this increase isn’t keeping pace with warming. As the group reports in the paper, a rise in temperature of 1°C tends to lower yields by 10% in countries that aren’t at high latitudes.


Written by Arhopala Bazaloides

May 8, 2011 at 2:12 pm

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