Global warming a risk to food supply, says draft United Nations report

Climate change will pose sharp risks to the world's food supply in coming decades, potentially undermining crop production and driving up prices at a time when demand for food is expected to soar, scientists have found.

In a departure from an earlier assessment, the scientists concluded that rising temperatures would have some beneficial effect on crops in some places, but that globally, they would make it harder for crops to thrive.

And, the scientists said, they were already seeing the harmful effects in some regions.

The warnings come in a leaked draft of a report under development by a UN panel, the Intergovernmental Panel on Climate Change. The document is not final and could change before it is released in March.

The report also finds other sweeping impacts from climate change occurring across the planet, and warns that these are likely to intensify as human emissions of greenhouse gases continue to rise. The scientists describe a natural world in turmoil as plants and animals attempt to migrate to escape rising temperatures, and warn that many could become extinct.

The warning on the food supply is the sharpest in tone that the panel has ever issued. Its previous report, in 2007, was more hopeful. While it did warn of risks and potential losses in output, particularly in the tropics, that report found that gains in production at higher latitudes would likely offset the losses and ensure an adequate global supply.