Global warming is creating a drag on production of the world's leading food and feed crops, as well as the raw materials for biofuels, according to scientists at Lawrence Livermore National Laboratory and the Carnegie Institution at Stanford University. In today's edition of the journal Environmental Research Letters, two ecologists report that yields of corn, wheat and barley have declined by about 40 million tons every year since 1981 from what farms worldwide should have produced. The annual value of those lost crops is about $5billion.
Crop yields, in general, are climbing, continuing to ride almost half a century of improvements in plant varieties, fertilizers and irrigation. But new analysis by Livermore climate scientist David Lobell and Christopher Field, head of Carnegie's Department of Global Ecology at Stanford, concludes the gains have been retarded by rising heat around the globe in the last 20 years.
"At least for wheat, corn and barley, temperature trends in the last few decades have been in the direction of holding yields down," Field said. "They're still increasing,but if temperatures hadn't been warming, they would have been increasing more."
For wheat and corn alone, the annual global losses are equal to the wheat and corn production of Argentina. The researchers likened the effect of global warming on crops to driving a car with the parking brake on. As a result, they said, farmers and plant scientists will have to work harder at meeting rising food demand — and harder still if farming for energy as well.
"Climate change impacts aren't something that might happen in the future. They're something we're seeing now," said Field. "We are already seeing real, negative impacts of warming that has already occurred."
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