America's breadbasket isn't where it used to be. The epicenter of agricultural production has moved north and west over the past half-century, and that trend will likely continue at an accelerated pace due to global warming, a new study finds.

Published yesterday in the online version of the journal Nature Climate Change, the study depicts how such a shift could put new strains on U.S. infrastructure, as rails and trains replace riverboats as the primary mode of agricultural transportation.

"You're definitely going to need to expand loading and export facilities and bolster the strength of your rail lines from North Dakota west and east," said Bruce McCarl, a regents professor with the Department of Agricultural Economics at Texas A&M University. "This is a 50-year expansion we're talking about."

The agricultural sector already places significant demand on the nation's transportation infrastructure, making up 22 percent of all transport tonnage.

Of that total, grain holds the largest share. Yet even that could change, as evaporating temperature barriers allow corn production to expand in the rich soils of Minnesota and the Dakotas. Acre for acre, corn yields are three times as heavy as wheat.

"That means you're moving three times the volume," McCarl said. "That puts new demand on the infrastructure to move it."

A switch from boats to rails

In the past, the Mississippi River has been the chief conduit for American grain, but a number of factors are curbing its role. The study found that corn production has shifted 150 miles northwest since 1950 and will likely continue that trajectory if warming patterns continue as projected. Higher temperatures could also lower the water levels of the Mississippi, making barge transport more expensive.

At the height of last summer's drought, the river fell to its lowest level since 1988, and commerce had to be suspended for several days.

Rail transport, meanwhile, will need to increase "from 8-14 percent due to the more northward shifts in crop mix and a reduction in proximity to the river system," the study says. That will mean more rail lines but also grain elevators, sidings and short-line rail track beds.

Truck transportation will likely increase as well, though to a slightly lesser extent.

If infrastructure keeps pace with shifting production, the United States could play an even greater role in international food markets than it does today. While rising temperatures could unlock fertile areas of the Dakotas and Minnesota, as well as other Great Lake states and provinces, food production is set to decline in more equatorial regions of the world, leading to greater demand for U.S. crops.

The increased demand will require more export terminals, particularly in the Northeast and Northwest. Larger volumes of crops could be moved via the Great Lakes, though lower water levels there could raise transportation costs as well.

The United States is a major world supplier of many agricultural products and is the largest producer of corn, growing about a third of the global crop, according to the Department of Agriculture.

U.S. farmers produce about $143 billion worth of crops and about $153 billion worth of livestock annually.

Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC. www.eenews.net, 202-628-6500