USDA study finds wide-ranging effects of rising temperatures

Climate change is likely to drive up corn prices and decrease productivity, costing the Corn Belt between $1.1 billion and $4.4 billion a year, according to a federal study released over the weekend.

The report by the U.S. Department of Agriculture's Economic Research Service modeled the effects of varying scenarios of climate change on agriculture between now and 2030 and predicted how farmers might react by altering crop and production practices. The study overall found that climate change will have complex effects on production that vary from region to region and from crop to crop.

The complexity comes from the numerous ways that climate change is likely to act on agriculture, including increasing temperatures, changing precipitation patterns, influencing pest distributions, changing soil fertility and increasing the frequency of extreme weather events.

According to the report, which studied only the largest commodity crops, corn and soybeans will likely see the biggest impacts. Climate change will likely decrease crop yields, shift production and increase prices by up to 22 percent for soybeans and 6 percent for corn.

At the same time, the yields of several other crops, including cotton, could increase.

The report found that climate change will increase the number of agricultural acres in the United States by 0.2 to 1 percent as farmers adapt by expanding acres and switching crops. The changes vary on a regional basis: Southern farmers, for example, could increase their acreage by up to 5 percent, while the change in the Corn Belt will be more marginal.

Nationwide loss to agriculture will depend on the severity of climate change and whether farmers adapt accordingly. Net returns to farmers under climate change range from an increase of $3.6 billion to a loss of $1.5 billion a year, according to the report.

In the Corn Belt, losses are likely to occur even under the mildest climate change scenarios and could reach up to $4.1 billion a year. The changing climate there could also make pests more potent, increasing losses by a further $600 million a year.

Pests could also wipe out gains in areas where climate change has meant increased productivity, the report says.

Climate change could also have significant effects on the natural environment because of the expanded crop acreage. The study projects that nitrogen runoff will increase by between 1.4 and 5 percent, and that soil erosion could rise by up to 1.2 percent.

Farmers have a number of options available to them to adapt, beyond expanding their acres or switching crops. They could alter their planting schedules, apply different fertilizers or adopt new methods of production, for example.

But in some cases, adaptation could have detrimental consequences. Adaptation could, for example, drive down the prices of the most important crops in a region, the report says.

USDA notes that the study comes with some limitations. It did not, for example, look at daily changes in temperature and precipitation, focusing instead on long-term averages. The study also did not examine specialty crops like fruits and vegetables.