June 5, 2007
US corn harvests, livestock production may be severely reduced in thirty years due to climate change
An initial draft of the first major climate five-year report by the US Department of Agriculture says global warming could cut down US corn yields by 1.5 percent in the next 30 years which could severely affect the livestock industry.
US crops were valued at US$122.4 billion in 2006, with corn accounting for $33.8 billion and these, according to the USDA, will be largely disrupted by more wildfires, longer droughts and greater heat stress which will push people to change land and water management.
The report was based on observed effects of climate change on US agriculture, rather than the computer models used in past studies, David Schimel, a lead writer of the report, said before it was released. The initial document is less optimistic than the USDA's 2002 climate report, he said.
The negative effects on crops may be alleviated by increased levels of soil-nurturing carbon dioxide, the report said. Rice and soybean yields may increase in some regions of the country, the USDA said.
The report, prepared with help from the National Science Foundation, the Department of Energy and other federal agencies, is subject to revision and peer review and completion is hoped to be until the end of the year, Schimel said.
A recent United Nations report said the threat of melting snow and ice caused by climate change could cut water supplies and flood coastal areas, affecting hundreds of millions of people worldwide.
Increased temperatures are likely to add stress to crops and animals that experience more hot days, reducing the quality of pollination, grain-growing and fruit development in plants and slowing animal development, the report states.
Agribusiness companies such as Archer Daniels Midland Co. and Cargill Inc. will experience changing growing seasons of grains which is largely due to greater heat but it planting will helped by carbon dioxide, the report states. The costs of adapting will force some smaller farmers out of business, it also said.
Cattle kept on feedlots and produced for Tyson Foods Inc., Swift & Co. and other meatpackers will face additional heat stress because of climate change. Annual losses may reach US$94 million for confined swine, beef and dairy animals by 2040, the report states, adding that the estimate may be understated as it doesn't account for losses from catastrophic weather events, which can cost US$25 million or more per event. The US beef market alone was worth US$71 billion in 2006, according to the USDA.
Greater weather volatility caused by global warming will have some of its greatest effect on water quality and availability, the report said.
Overall rainfall levels could increase up to 8 percent in the northeast, while western states could face more prolonged droughts, the report stated.
The amount of rainfall areas received is sometimes less important than how useful its moisture is to crops, Schimel said. For example, there is a new tendency for California's moisture to come more from rain and less from snowpack, which requires changes in irrigation management, he said. Rain is also evaporating faster, leaving less water for almonds and grapes from the state's Central Valley, he said.
Wildfires--which last year burned more than 9.9 million US acres, the most since at least 1960--will become more frequent due to number of low humidity days and this can further taxing productive land, the study states. It will be more prevalent in the western US, USDA says.
The report didn't delve deeply into the economic impact on agriculture and also cautioned that farmers and ranchers will be able to mitigate some adverse effects through adaptation.
As climate science progresses, the next step is to teach farmers how to adjust to problems that are too far along to simply go away, said Shrikant Jagtap, a climate scientist who worked on the 2002 report.
He said increasing the people's capacity to absorb these shocks may at least alleviate the situation.
