Rising Heat Threatens World Food Supplies
By Brandon Keim, Wired Science, January 08, 2009
(Flickr/Hamed Parham)
Projected global temperature increases/Science
The hottest seasons of the 20th century will be typical weather by 2100 — and scientists think that without agricultural adaptations to extreme heat, mass food shortages could follow.
"We wanted to say: let's look at the worst cases we can think of in recent decades. Think about how hot that was. Everything in the future will be hotter. Even the coldest years will be hotter," said Rosamond Naylor, director of Stanford University's Program on Food Security and the Environment.
Naylor and University of Washington climatologistDavid Battisti averaged the temperature projections from the 23 global climate models used by the Intergovernmental Panel on Climate Change in its most recent report. They calculated a 90 percent chance of massive temperature increases during the growing seasons of most of the world.
Heat waves accelerate plants' development and the amount of water they require — a thirst that often is not slaked. The IPCC estimates that for degree Celsius the average growing season temperatures rise, grain harvests will fall by between 2.5 and 16 percent.
If those numbers seem abstract, explain Battisti and Naylor in a paper published Thursday in Science, the historical record is not.
During Western Europe's record heat wave of 2003, maize production fell by 30% in Italy and France, with wheat and fruit harvests declining by one-quarter. Three decades earlier, record heat in the Soviet Union disrupted the wheat harvest, causing a worldwide tripling of wheat prices — an early foreshadowing of how local problems can ripple through a globalized agricultural economy.
The food crisis of 2008, when growing grain demands and fears of drought caused rice prices to spike by 50% in two weeks in March, made graphically clear the precariously interconnected nature of global agriculture. Some countries cut rice exports, driving prices even higher; others outlawed private hoarding of food; and riots broke out in 33 countries.
All that took place without the sort of heat-induced stresses predicted by climatologists.
For an example of what adding heat into the mix can do, write Naylor and Battisti, look to the ongoing famine in Africa's Sahel region. A decades-long drought finally ended, but was followed by rising temperatures. Farming has been crippled, perhaps permanently. An estimated 275,000 children die there each year from malnutrition.
Temperatures will rise most and have the harshest consequences in the tropics and subtropics, where several billion people already walk a fine line between subsistence and impoverishment. But temperate regions will not escape unscathed, environmentally or economically.
"As policymakers, as people, we tend not to deal with problems until they are very severe," said Per Pinstrup-Andersen, a Cornell University agricultural economist and World Food Prize laureate. "We know that we're going to have a huge problem unless we as a society begin to to take this seriously — and that means a lot more adaptation."
Scientists must develop crops suited to Earth's new climate, Naylor and Battisti argue. Better techniques, such as highly efficient irrigation systems and spoilage-reducing harvesting methods, are also required. So are alternatives to fossil fuel-intensive fertilizers and pesticides.
But investment in agricultural research has waned in recent decades, they write, at precisely a time when modern food output is "insufficient to meet near-term food needs in the world's poorest countries, to say nothing of longer-term needs in the face of climate change."
Pinstrup-Andersen echoed their analysis. "Right now, the countries that should be investing in agricultural research are investing very little," he said. "This research will take a considerable amount of time to complete. We have time — but we have to start investing now."
Those proscriptions are basic and relatively attainable. More controversial and complicated is reform to the global agricultural system.
"Two-thirds of all developing countries are net food importers," said Steve Suppan, a senior policy analyst at the nonprofit Institute for Agriculture and Trade Policy. In these countries, said Suppan, formerly agrarian economies were reorganized around service and manufacturing — but promised riches failed to materialize, leaving nations both impoverished and unable to feed themselves.
Pinstrup-Andersen disagreed with Suppan's recommendation, saying that national food self-sufficiency would be expensive and disruptive, throwing isolated nations at the mercy of regional weather shifts. Instead, Pinstrup-Andersen recommended even more globalization, and harsh punishments for countries that turn protectionist.
The fates of these countries are uncertain — unlike, said Naylor, the changing climate.
"With the temperature projections, there's no disputing where we're heading," she said. "We have to face reality."
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