World's Most Important Crops Hit by Global Warming Effects

http://www.commondreams.org/headlines07/0319-05.htm

World's Most Important Crops Hit by Global Warming Effects
by Steve Connor


Global warming over the past quarter century has led to a fall in the yield of some of the most important food crops in the world, according to one of the first scientific studies of how climate change has affected cereal crops.

Rising temperatures between 1981 and 2002 caused aloss in production of wheat, corn and barley that amounted in effect to some 40 million tons a year - equivalent to annual losses of some £2.6bn.

Although these numbers are not large compared to the world-wide production of cereal crops, scientists warned that the findings demonstrated how climate change was already having an impact on the global production of staple foods. "Most people tend to think of climate change as something that will impact the future, but this study shows that warming over the past two decades has already had real effects on global food supply," said Christopher Field of the Carnegie Institution in Stanford, California.

The study, published in the journal Environmental Research Letters, analysed yields of cereals from around the world during a period when average temperatures rose by about 0.7C between 1980 and 2002 - although the rise was even higher in certain crop-growing regions of the world.

There was a clear trend, showing the cereal crops were suffering from lower yields during a time when agricultural technology, including the use of chemical fertilisers and pesticides, became more intensive. The study's co-author, David Lobell of America's Lawrence Livermore National Laboratory in California, said that the observed fall in cereal yields could be clearly linked with increased temperatures during the period covered by the study.

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