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How global warming goes against the grain

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Agricultural researchers with the CGIAR thought the decline in wheat-growing capacity of the plain, which includes the Punjab, was so worrisome they hurriedly made the finding public, although the full study in which it is described, called "Can Wheat Beat the Heat?" is not going to be released until later this year.

That such a fabled agricultural region — source of one-sixth of the global wheat crop — could be severely affected by rising temperatures holds symbolic importance, because the Indo-Gangetic Plain represents one of the world's most significant victories against food shortages.

The area "really is the epicentre of the green revolution in the 1970s, where wheat and rice scientists saw the first big gains that were coming out of modern plant-breeding techniques," says Nathan Russell, a spokesman at the CGIAR, which is based in Washington.

The worry is that climate change might "erase all of these gains," he says.

Perhaps the best-known worrier about climate change and its impact on agriculture is Lester Brown, founder of the Earth Policy Institute, a U.S. environmental think tank, and proponent of the view that global warming and agriculture are on a collision course.

"It certainly looms large," Mr. Brown says of the threat posed to farming by a warmer world.

Mr. Brown says the global food larder is already so bare that the impact of global warming could be felt at any time — even as early as this summer — if it causes rising temperatures or changing precipitation patterns that lead to a crop failure in any major agricultural region.

The food surpluses of yesteryear have been nibbled down to the point where practically nothing is left in the bin for coping with even one disappointing harvest, he says.

"The unfortunate reality is that the cushion for dealing with climate change now is less than it's been for 34 years, because in six out of the last seven years world grain production has fallen short of consumption."

Furthermore, one of the solutions to global warming — using crops to produce clean-burning bio-fuels such as ethanol — would accentuate any harvest shortfalls because so much corn, sugar, and soybeans is now being diverted from the dinner plate to the gas tank.

The Earth Policy Institute tracks the world's stockpile of grain — the amount available in storage after accounting for annual use and production — and says it's down to only 57 days of consumption. This is close to the modern nadir, a period in the early 1970s of poor harvests when levels fell so low there was only enough for 56 days. That earlier period of short supply prompted a doubling of world grain prices — an indication of the possible consequences if global warming takes a bite out of harvests.

Even North America's prime piece of agricultural real estate, the continent's equivalent of the Indo-Gangetic Plain, is in the gunsights of climate change.

The models that simulate the likely effects of climate change show that the regions warming the most are at mid to high latitudes, and in mid-continental areas far from the moderating effects of oceans.

"Those conditions sort of describe the U.S. corn belt and the Great Plains, the wheat-growing Great Plains of the U.S. and Canada," Mr. Brown says. "Since we are the world's bread basket, if we start losing wheat production and corn production, it's going to affect the entire world."

The study released by CGIAR did find that rising temperatures would cause a remarkable northward shift of the wheat belt. The crop could theoretically be cultivated in a band across the top of North America — from Cape Harrison, about midway up the coast of Labrador, to Ketchikan, on the Alaskan panhandle, in the west.

But agricultural experts say don't bother hoping for northern regions to become replacement granaries for losses in the tropics. Trading the rich soils of the Punjab or the U.S. Midwest for the thin soils of Labrador and the north coast of Lake Superior, in other words, is a bit like a gambler discarding an ace for a two. It's probably an unwise bet.

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