By Christine Stebbins

AMES, Iowa, Aug 31 (Reuters) - Iowa State University researchers will join a study of climate change to produce mid-century projections by late next year of the likely regional effects on North American farms from global warming.

"There is no question now that the climate is changing on a global scale," said Gene Takle, an Iowa State University professor of geological and atmospheric sciences who will lead a study to project North American climate from 2040 to 2070.

Iowa and Illinois are the epicenter of the U.S. Midwest farm belt, which produces the world's largest exportable surpluses of corn, soybeans and wheat and vast amounts of meat, dairy products, poultry and vegetables.

Takle said in an interview with Reuters that the research should give farmers, water managers, environmental engineers, transportation specialists and other professionals a better idea of what the climate will be in the years ahead.

"If the climate is changing, you can't stop it over the next 50 years," Takle said. "What's coming is coming and we better be prepared to adjust to it."

Researchers at the National Oceanic and Atmospheric Administration this week said that greenhouse gas emissions pushed U.S. temperatures in 2006 close to a record high.

The annual average U.S. temperature last year was 2.1 degrees F (1.16C) above the 20th century average and the ninth consecutive year of above-normal U.S. temperatures.

The latest scientific consensus from the Intergovernmental Panel of Climate Change (IPCC) earlier this year said that in coming decades "warming is expected to be greatest over land and at high northern latitudes, and least over the Southern Ocean and parts of the North Atlantic Ocean."

The Iowa research will be part of an international group of scientists collaborating on the North American Regional Climate Change Assessment Program, directed by the National Center for Atmospheric Research in Boulder, Colorado.

Current trends in Iowa point to a more humid Corn Belt, which could be a positive for Midwest agriculture, Takle said. But he and others are concerned about total effects.

"We can start to talk about things like how the intensity of precipitation will change. That's very important for farmers because if precip is more intense it can affect things like soil erosion ... it might be more damaging to their crops," said Bill Gutowski, an Iowa State scientist on the project.

The researchers say Iowa annual precipitation has increased by about an inch over the past 30 years but more of that is happening in extreme weather. In other words, Takle said, there are more 3-inch rains than there were 30 years ago.

Winter low temperatures aren't as cold, which has meant about eight more frost-free days than there were in the 1950s, Takle said. That makes for a longer growing season.

The summer heat also isn't as intense as it was 30 years ago, but the humidity is rising, Takle said.

"It appears rainfall will be increasing to the north and decrease to the south of us. For us in the farm belt we don't see any clear-cut changes in either direction," Gutowski said.

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