The group brings together experts from 15 agricultural research centers around the world funded by states, international organizations and private foundations.

By now, the threat of global warming is a familiar one: many scientists believe rising global temperatures, exacerbated by combustion of fossil fuels, will bring warmer, wetter and more violent weather. That in turn is expected to raise sea levels and threaten the life and livelihood of millions, especially in coastal areas.

But farm and food experts gathered for the group's annual meeting this week focused on how climate change will affect harvests.

They said warming could bring more drought and shorter growing seasons to places like Tanzania and Mozambique, increase flooding in coastal areas of countries including Bangladesh, and reduce crop yields in countries like Colombia.

The effect of global warming on farmers will be spotty, said Robert Zeigler, director general of the International Rice Research Institute in the Philippines.

It might boost potato yields in the northern hemisphere, he said, but cut them across Africa, South and East Asia, and northern South America, where the potato is a staple crop and people are more likely to go hungry.

Experts said the first step to countering the looming threat is further research that will produce weather and crop forecasts than can inform policymakers' decisions.

Development of hardier "climate-ready" crops that can withstand warmer climates and resist water and salt is also needed, they said. Climate-sensitive management, including more efficient use of water, will also help.

Zeigler said some of that research is already happening, including development of drought-tolerant maize in southern Africa, but it needs to be accelerated.

To help that happen, agriculture experts are working to forge ties with the climate change community.