But output of the corn crops grown today could fall as much as much as 5 percent in coming decades as expected higher temperatures brought on by greenhouse gas emissions cause droughts and weaken plants, scientists said in a US Department of Agriculture report released on Tuesday.

The report synthesized peer-reviewed studies on how climate change would affect agriculture, most of which assumed US temperatures would rise about 1.2 degrees Celsius over the next 30 to 50 years, as indicated by the UN's Intergovernmental Panel on Climate Change report last year.

"We're running into a situation in which we have the greater likelihood of occurrences of extreme temperature events during critical growth stages of that crop," Jerry Hatfield, the lead author of the agriculture section of the report, said about corn in a teleconference.

Corn is the top US crop and is the main feedstock for the country's ethanol industry. Soybeans are second place, with soyoil used to make biodiesel.

Hatfield said many crops like corn are already grown near the highest temperatures they can stand, which makes them vulnerable to warmer weather. Other crops, like soybeans, can withstand higher temperatures, which means higher temperatures may increase their yield, he said.

The report did not project how yields would change should growers change to corn varieties that could be more drought or temperature resistant.