A leaked draft of a report by the Intergovernmental Panel on Climate Change said that climate change could reduce output and send prices higher in a period when global food demand is expected to soar.
In a departure from an earlier assessment, the scientists concluded that rising temperatures will have some beneficial effects on crops in some places, but that globally they will make it harder for crops to thrive — perhaps reducing production over all by as much as 2 percent each decade for the rest of this century, compared with what it would be without climate change.
And, the scientists say, they are already seeing the harmful effects in some regions. The warnings come in a leaked draft of a report under development by a United Nations 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 already 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 colonize new areas to escape rising temperatures, and warn that many could become extinct.