The changes created "a very serious risk that fewer people will be able to get food," particularly in the developing world, said Jacques Diouf, head of the UN Food and Agriculture Organization.
The agency's food price index rose by more than 40 percent this year, compared with 9 percent the year before - a rate that was already unacceptable, he said. New figures show that the total cost of foodstuffs imported by the neediest countries rose 25 percent, to $107 million, in the last year.
At the same time, reserves of cereals are severely depleted, FAO records show. World wheat stores declined 11 percent this year, to the lowest level since 1980. That corresponds to 12 weeks of the world's total consumption - much less than the average of 18 weeks' consumption in storage during the period 2000-2005. There are only 8 weeks of corn left, down from 11 weeks in the earlier period.
Prices of wheat and oilseeds are at record highs, Diouf said. Wheat prices have risen by $130 per ton, or 52 percent, since a year ago. US wheat futures broke $10 a bushel for the first time yesterday, the agricultural equivalent of $100 a barrel oil.
Diouf blamed a confluence of recent supply and demand factors for the crisis, and he predicted that those factors would be here to stay. On the supply side, these include the early effects of global warming, which has decreased crop yields in some crucial places, and a shift away from farming for human consumption toward crops for biofuels and cattle feed. Demand for grain is increasing with the world population, and more is diverted to feed cattle as the population of upwardly mobile meat-eaters grows.
"We're concerned that we are facing the perfect storm for the world's hungry," said Josette Sheeran, executive director of the World Food Program, in a telephone interview. She said that her agency's food procurement costs had gone up 50 percent in the past 5 years and that some poor people are being "priced out of the food market."
To make matters worse, high oil prices have doubled shipping costs in the past year, putting enormous stress on poor nations that need to import food as well as the humanitarian agencies that provide it.
"You can debate why this is all happening, but what's most important to us is that it's a long-term trend, reversing decades of decreasing food prices," Sheeran said.
Climate specialists say that the vulnerability will only increase as further effects of climate change are felt. "If there's a significant change in climate in one of our high production areas, if there is a disease that affects a major crop, we are in a very risky situation," said Mark Howden of the Commonwealth Scientific and Industrial Research Organization in
Already "unusual weather events" linked to climate change - such as droughts, floods, and storms - have decreased production in important exporting countries such as
In Southern Australia, a significant reduction in rainfall in the past few years led some farmers to sell their land and move to
Sheeran said that on a recent trip to
Diouf suggested that all countries and international agencies would have to revisit agricultural and aid policies they had adopted "in a different economic environment." For example, with food and oil prices approaching record highs, it may not make sense to send food aid to poorer countries, but instead to focus on helping farmers grow food locally.
The Food and Agriculture Organization plans to start a new initiative that will offer farmers in poor countries vouchers that can be redeemed for seeds and fertilizer, and will try to help them adapt to climate change.
The recent scientific data concluded that farmers could adjust to up to 5.4 degrees Fahrenheit of warming by switching to more resilient species, changing planting times, or storing water for irrigation, for example.
But after that, "all bets are off," said Francesco Tubiello of the Columbia University 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."
Diouf noted that there had been "tension and political unrest related to food markets" in a number of poor countries this year, including