Up to 50 million people, mostly in Africa, can face hunger by 2050 due to climate change and reduced crop yields, scientists predict.
Roughly 500 million people worldwide already experience food shortages but rising levels of greenhouse gases could make the problem worse.
"We expect climate change to aggravate current problems of the number of millions of people at risk of hunger, probably to the tune of 50 million," said Professor Martin Parry of the Hadley Centre of the UK Meteorological Office.
Parry told the British Association science conference that it would take huge reductions in emissions of greenhouse gases -- about 20 times those required by the Kyoto Protocol -- to avoid the additional risk of hunger.
The United States, by the way, the world's biggest polluter, has refused to back the protocol, saying it would hurt its economy, Reuters reports.