Higher Yields of Trouble for Farmers

Report Predicts Tough Times for U.S. Agriculture

A new report led by NOAA forecasts a host of climate change challenges for farmers in the years ahead, writes Tom Kenworthy.

Jerald Phelps looks over his drought-damaged corn crop on his farm near Ulysses, KS. A new report predicts more climate-related harm to U.S. agriculture. (AP/Charlie Riedel)
Jerald Phelps looks over his drought-damaged corn crop on his farm near Ulysses, KS. A new report predicts more climate-related harm to U.S. agriculture. (AP/Charlie Riedel)

America’s farmers, who must deal with great uncertainty even in the best of times, face a daunting future in a warming world. That is the sobering message for U.S. agriculture in a new report by the U.S. Global Change Research Program, “Global Climate Change Impacts in the United States.” The report—released today while clean-energy legislation is debated on Capitol Hill—was led by the National Oceanic and Atmospheric Administration and predicts that changes in climate “are likely to increasingly challenge the United States capacity to efficiently produce food, feed, fuel, and livestock products.”

Unchecked global warming pollution means that the vast enterprise that annually produces more than $200 billion in food and livestock and helps feed the world will have to contend with more extreme weather events such as heavy downpours and droughts; tougher battles with weeds, plant diseases, and insect pests; declining forage and pasture quality; and heat, disease, and weather stresses that will reduce livestock productivity.

Release of the climate change impacts analysis comes at a critical juncture in the unfolding political struggle to craft policies to transition to a clean-energy economy that would create jobs, reduce oil use, and cut greenhouse gas pollution. Many farm belt lawmakers are among the toughest critics of the American Clean Energy and Security Act, H.R. 2454, legislation that is likely to go before the full House in the next few weeks.

Those legislators want greater participation by farmers in carbon offset programs, less oversight by the Environmental Protection Agency and more by the Agriculture Department, and changes in how the carbon footprint for biofuels is calculated.

Agricultural interests would do well to consider the high costs of inaction as outlined in the climate change impacts report while negotiations on possible compromises between farm state lawmakers and House leadership proceed. The complex interplay of higher temperatures, both more heavy downpours and water shortages, and weed species will affect U.S. agriculture, its crops, and different regions in a variety of ways—some beneficial, many not.

Global warming has already brought higher temperatures. This is the hottest decade in recorded history. And still hotter temperatures are ahead of us. That will mean longer growing seasons, which are good for some vegetable crops that do well in heat such as melons and sweet potatoes. But it will shorten seasons for cool weather crops such as lettuce and spinach.

For grain crops that are a huge part of the U.S. farm economy the faster growth that comes with warmer temperatures means less time for the seeds to grow and mature.

“Even moderate increases in temperature will decrease yields of corn, wheat, sorghum, bean rice, cotton, and peanut crops,” predicts the report. “Further, as temperatures continue to rise and drought periods increase, crops will be more frequently exposed to temperature thresholds at which pollination and grain-set processes begin to fail and quality of vegetable crops decreases.”

We have already seen significant crop yield reductions due to climate change: Global wheat, maize, and barley production in 2002 would have been 2 percent to 3 percent higher if not for the long-term yield limiting effects of global warming trends. The combined 2002 losses in productivity worldwide cost farmers over $4.8 billion at 2002 prices.

It seems counterintuitive, but warmer temperatures can also mean greater crop damage from frosts. Warmer winters and earlier springs will mean earlier plant development and maturation, exposing some crops to damage from late season frosts. Soon, climate change could cost corn growers in the United States alone over $1.4 billion annually. Already, increased temperatures and carbon dioxide levels have created a yield loss of about 3 percent.

Changes in the availability of water, including the timing and amount of rain and melting snow, will also pose major challenges for farmers. Both too little water and too much at the wrong time will decrease yields.

“One of the most pronounced effects of climate change is the increase in heavy downpours,” says the report. “Precipitation has become less frequent but more intense, and this pattern is projected to continue across the United States.” That trend will delay spring planting while flooding fields during the growing season. Such heavy rains in the spring of 2008 alone caused agricultural losses in the range of $8 billion, while total weather-related losses between 1980 and 2005 destroyed at least $43.6 billion worth of crops, or an average of $1.7 billion per year.

The report found that heavy rain downpours that lead to flooding and agriculture damage have increased over the last 50 years. They have increased by 27 percent in the Midwest, 18 percent in the Southeast, and 13 percent across the Great Plains states. According to the report these downpours are “projected to increase further.”

At the same time under business as usual the frequency and severity of droughts will also increase at the very time that crops will need more water because of rising temperatures.

The report projects that the Southwest will experience a significant decline in precipitation between now and 2080—by as much as 30 percent in some places. A study for Science magazine in 2007 reported that the drought conditions of the Dust Bowl during the 1930s will become the new norm in the American Southwest by 2050. Providing enough water to the western states to combat a repeat of such horrors will cost $950 billion per year by 2100, representing 0.93 percent to 1 percent of U.S. GDP.

Control of pests, diseases, and weeds will become a larger problem for farmers, and dealing with them will increase costs for herbicides and pesticides.

“Weeds benefit more than cash crops from higher temperatures and carbon dioxide levels,” notes the report, and invasive weeds will spread northward. The $11 billion that farmers now spend on weed control will grow, and the most widely used herbicide will become less effective at higher carbon dioxide levels.

In addition, “Many insect pests and crop diseases thrive due to warming, increasing losses and necessitating greater pesticide use…Rising temperatures allow both insects and pathogens to expand their ranges northward.” With warmer winters, more insects will survive. And more pesticides and herbicides will lead to higher surface and groundwater contamination.

Livestock producers also will face an array of challenges. Dramatic changes are already underway in western rangelands, where higher levels of carbon are reducing the quality of forage and promoting the invasion of shrubs and invasive annuals such as cheat grass. Poor quality forage “could have pronounced detrimental effects on animal growth, reproduction, and survival, and could render livestock production unsustainable unless animal diets are supplemented,” the report predicts.

Livestock productivity will also suffer from higher temperatures, weather extremes, and higher rates of disease. Warmer temperatures and higher humidity will stress animals, reducing their rates of growth, reproduction, and ability to produce milk. “The more the U.S. climate warms, the more production will fall,” the analysis concludes. “[S]wine, beef and milk production are all projected to decline in a warmer world.”

American farmers in the years ahead will face a gauntlet of challenges that will test their resilience and innate sense of optimism, and threaten their income as never before. The tumultuous future outlined by scientists in the climate impacts report in the absence of pollution reductions is a compelling reason for farmers and their representatives in Congress to support the American Clean Energy and Security Act.

Tom Kenworthy is a senior fellow at the Center for American Progress. Thanks to CAP interns Austin Davis and Daniel Sanchez.

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Tom Kenworthy

Senior Fellow