Climate risks to global agriculture are underestimated

Vulnerability of global agricultural to climate change may be underestimated by experts, warns a trio of papers published in week’s issue of the Proceedings of the National Academy of Sciences (PNAS). The research says that "progressive changes predicted to stem from 1- to 5-degree C temperature rises in coming decades fail to account for seasonal extremes of heat, drought or rain, multiplier effects of spreading diseases or weeds, and other ecological upsets," according to a statement from Columbia University's Earth Institute.

"Many people assume that we will never have a problem with food production on a global scale. But there is a strong potential for negative surprises," said Francesco Tubiello, a physicist and agricultural expert at the NASA/Goddard Institute of Space Studies who coauthored all three papers.

The researchers say that current grain production—from which humans derive two-thirds of their protein—would need to double before 2100 in order to keep pace with demand from population growth, but that agricultural gains in temperate regions would not be enough to offset declining productivity in the tropics, due to higher temperatures and reduced precipitation. By some estimates, developing countries may lose 135 million hectares (334 million acres) of prime farm land in the next 50 years.

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"The projections show a smooth curve, but a smooth curve has never happened in human history," he said. "Things happen suddenly, and then you can't respond to them."
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