Heat may spark world food crisis

The race is on to breed maize which can tolerate the heat of future summers

Half the world's population could face climate-induced food crisis by 2100, a new report by US scientists warns.

Rapid warming is likely to reduce crop yields in the tropics and subtropics, according to Prof David Battisti of Washington University in Seattle.

The most extreme summers of the last century will become the norm, he calculates, using 23 climate models.

We must urgently create crops tolerant to heat and drought if we are to adapt in time, he writes in Science journal.

"The stresses on global food production from temperature alone are going to be huge," said Mr Battisti, a professor of atmospheric sciences.

"And that doesn't take into account water supplies stressed by the higher temperatures."

He collaborated with Professor Rosamond Naylor, director of Stanford University's Program on Food Security and the Environment, to examine the impact of climate change on the world's food security.

Beyond extreme

The duo combined direct observations with projections from 23 global climate models that contributed to the Intergovernmental Panel on Climate Change's (IPCC) 2007 global assessment.

They calculate there is greater than 90% probability that by 2100, the average growing-season temperatures in the tropics and subtropics will be higher than any temperatures recorded there to date.

"We are taking the worst of what we've seen historically and saying that in the future it is going to be a lot worse unless there is some kind of adaptation," said Professor Naylor.

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