Falling crop production resulting from extreme weather events, diseases and pest infestations increasingly will be fueled by global warming and create an uncertain future for U.S. agricultural production and the nation's food supplies, according to leading experts gathered in Washington, D.C., at a Harvard Medical School Center for Health and the Global Environment briefing, made possible by the Civil Society Institute, the Energy Foundation and the National Environmental Trust.

A news media event was followed by a congressional staff briefing sponsored by Sen. Harkin (D-Iowa), Sen. Brownback (R-Kan.), Sen. Bill Nelson (D-Neb.) and Sen. Lugar (R-Ind.)

Not all the views from the experts were gloomy. Some noted that the impact of global warming can be lessened — and even turned into a boon for agricultural producers — if farmers take such steps as setting up wind farms, engaging in the production of “biodiesel” and ethanol fuels and participating in carbon sequestration programs.

Eric Chivian, director of the Center for Health and the Global Environment at Harvard Medical School said: “Since the 1970s, U.S. agricultural productivity has grown, but it has also experienced greater variability that has been, in part, climate-related. Extreme weather events (very high temperatures, torrential rains and flooding, and droughts) and crop diseases and pests have taken a heavy toll. Greenhouse warming is expected to lead in future years to even more intense and frequent extreme weather events, and to greater losses from diseases and from pests that may multiply more rapidly and expand their ranges.”

William Easterling, professor of agronomy and director of the Institutes of the Environment at Penn State University said: “Climate variability continues to exert large year-to-year swings in U. S. crop yields and production in spite of technology-driven gains in crop productivity over the 20th century. Recent persistent drought conditions in the western Corn Belt states have particularly affected wheat production. While experiments persuasively demonstrate the positive effects of rising atmospheric CO2 concentrations on photosynthesis of major crops such as soybeans and wheat and on the drought-tolerance of all crops, these effects are not likely to fully offset the potential stresses of warmer temperatures and drier soils, especially as the warming progresses. Crop modeling results … paint a consistent picture of crop yields being lower than today even in an environment with higher rainfall than now.”

More pests, disease

Among the big concerns for farmers when it comes to climate change: more pests and diseases. Recent warmer winters in northern production regions have increased winter pest survival and outbreaks of insect-borne viral diseases associated with them.”

However, global warming also could work to the advantage of some farmers, according to Charles W. Rice, professor of soil microbiology at Kansas State University. He noted: “Agriculture can help solve [the CO2] problem [through participation in carbon sequestration programs]. Crops and other plants remove CO2 from the atmosphere and convert it into organic carbon. After harvest, the organic carbon in residues and roots is deposited in the soil, where portions can remain for long periods … Benefits of carbon sequestration include increased soil fertility, reduced erosion, improved wildlife habitat and better soil and water quality.

“Recent estimates of the potential for U.S. agricultural soils to sequester carbon, using existing technologies, are on the order of … 15 percent of carbon emissions in the U.S. This estimate does not include biomass production for renewable fuels nor advancement in soil and agricultural sciences. Economic analyses suggest that soil carbon sequestration is among the most beneficial and cost effective option available for reducing greenhouse gases, particularly over the next 30 years until alternative energy sources are developed and become economically feasible.”

Energy source

U.S. farms also could serve as a major source of alternative energy supplies, including wind farming and biodiesel production. American Corn Growers Foundation CEO Dan McGuire said: “Renewable energy, including wind, ethanol and biodiesel offers the means to improve the environment and make our country more energy independent and secure while enhancing the rural and national economy. The Wind Powering America program of the U.S. Department of Energy projects that wind power could displace 35 million tons of atmospheric carbon by year 2020.

“In May 2000, biodiesel became the only alternative fuel to successfully complete the Environmental Protection Agency's Tier I and Tier II testing under Section 211 (b) of the Clean Air Act. The Department of Energy and the U.S. Department of Agriculture have calculated carbon dioxide reductions of 78 percent for biodiesel when compared with petroleum diesel in a full life cycle analysis. Biodiesel also reduces air pollutants linked to cancer by 80-90 percent vs. petroleum diesel.”