The report is in the journal Science.

One of the researchers was economist Wolfram Schlenker at Columbia University in New York and the National Bureau of Economic Research. He says the report can serve as a planning tool for policy makers.

WOLFRAM SCHLENKER: "If you are worried about rising food prices, it might be good to funnel some research into breeding for heat tolerance and maybe even drought tolerance."

Jeffrey Stark is with a public policy organization called the Foundation for Environmental Security and Stability. This group is supported by the United States Agency for International Development. Mr. Stark recently described the effects of climate change on pastoralists in Uganda. They travel with their cattle to find grasslands and water.

JEFFREY STARK: "We did hear repeatedly that there have been increasing temperatures, drying wetlands, less frequent but more intense rain, hail storms and, most significantly, unpredictable shifts in seasonal patterns. The pastoralists in the cattle corridor have to travel farther in search of pasture and water."

And that search, he says, can bring them into contact and conflict with farmers who have problems of their own.

And that's the VOA Special English Agriculture Report, written by Jerilyn Watson. For more stories, go to voaspecialenglish.com, where you can also find English teaching activities. You can also find captioned videos of our reports on YouTube at the VOA Learning English channel. I'm Bob Doughty.