Soaring food prices are very likely to become even more unstable because of global warming?s effect on farming, federal officials say. Their prediction punctuates a recent report published by the U.S. Department of Agriculture, the National Center for Atmospheric Research, and other agencies and scientists at several universities. The findings come at a time of turmoil for worldwide food supplies caused by natural disasters; the use of corn for producing ethanol; the skyrocketing cost of oil, which has created a surge in prices for basic grocery items; and growing global competition for wheat, milk and other staples.
The report?s authors say climate change offers a few potential positives, including longer growing seasons, which can help boost the productivity of pastureland and some crops. But overall, the forecast is grim, with projections of an increase in crop failures, the spread of weeds, diminished effectiveness of the herbicide glyphosate, more insect damage to crops and a rise in livestock deaths. The researchers also cite more signs of drought severity in the West. Extended water shortages could drive up costs, push more farmers out of business and send food prices even higher. ?Slight changes in things like temperature and precipitation can potentially have dramatic effects,? says Steven Archer, a lead author of the report and a professor of natural resources at the University of Arizona.
The report also addresses the likely future of the nation?s natural resources. It predicts that forest and range fires will become more common, soil erosion will increase and signature plants in the Southwest could disappear. Unlike many climate reports that make projections for 2100, this research team limited its time frame to the next 25 to 50 years.
??Scientists? climate models show much more certainty in the shorter time period than they do for a century or more. They say the world is locked into some amount of warming in the near term because of past greenhouse-gas emissions, but that the long-term future could be different if those emissions are lowered. ?There are advances that allow you to incrementally improve drought resistance and the ability of plants to retain water,? says Julian Schroeder, a biologist at the University of California San Diego. ?It?s hard to be optimistic right now, but one has to work on solutions.?
The report focuses on major crops such as corn and soy, which generally are less vulnerable to temperature changes than other produce. Plants have different optimal ranges for temperatures, frost-free days, carbon dioxide in the atmosphere, water and other factors. For corn, the USDA researchers predict that heat will drive down productivity in coming years ? an unwelcome forecast for the price of everything from tortillas to gasoline. Rice and beans could follow suit, while plants such as peanuts and cotton could benefit from having more carbon dioxide in the air.
Whatever happens to specific crops, the overarching issue will be water ? a commodity that?s in increasingly short supply in the West. The USDA report says a trend toward earlier snowmelt challenges irrigation systems that rely on the mountains releasing water slowly over several months.
Climate change is affecting ? and will continue to affect ? the nation?s water supplies, agriculture, land resources and biodiversity. The growing season has increased by 10 to 14 days over the past 19 years in many areas of the country. Higher temperatures will increase the risk of crop failures for certain grains, fruits and vegetables. Warmer winters will reduce livestock deaths, but that will be more than offset by greater mortality during hotter summers. More heat also will lessen the productivity of livestock and dairy animals. Weeds will spread north and become more resistant to herbicides. More carbon dioxide in the atmosphere will help young trees in good soils grow faster, but it also will cause more forest fires.