Global warming is already affecting the nation's forests, water resources, farmland and wildlife, and will have serious negative consequences over the next 25 to 50 years, according to a report issued yesterday by the federal government. The scientific assessment by the U.S. Climate Change Science Program, which was commissioned by the Agriculture Department and carried out by 38 scientists inside and outside the government, provides the most detailed look in nearly eight years at how climate change is reshaping the American landscape. The report, which runs 193 pages and synthesizes a thousand scientific papers, highlights how human-generated carbon dioxide emissions from burning fossil fuels have already translated into more frequent forest fires, reduced snowpack and increased drought, especially in the West.
Anthony C. Janetos, director of the Joint Global Change Research Institute of the University of Maryland and the Pacific Northwest National Laboratory, said the document aims to inform federal resource managers and dispel the public's perception that global warming will not be felt until years from now.
"They imagine all these ecological impacts are in some distant future," said Janetos, one of the lead authors, who noted that many animals and plants have shifted their migratory and blooming patterns to reflect recent changes in temperature. "They're not in some distant future. We're experiencing them now."
The document concludes that Americans must face the fact that many of these changes are locked in even if the country takes significant steps to cut emissions in the coming decades.
"Climate change is currently impacting the nation's ecosystems and services in significant ways, and those alterations are very likely to accelerate in the future, in some cases dramatically," the report says. "Even under the most optimistic CO2emission scenarios, important changes in sea level, regional and super-regional temperatures and precipitation patterns will have profound effects."
Richard Moss, vice president and managing director for climate change at the advocacy group World Wildlife Fund, said in an interview that the report represents "the very first upfront acknowledgment from the administration that we are already experiencing climate change impacts."
As recently as July 2007, the administration submitted a report to the United Nations that omitted any discussion of how global warming will affect wildfires, heat waves, agriculture or snowpack.
Moss, who led the U.S. Climate Change Science Program coordination office during both the Clinton and Bush administrations, praised the program for producing the analysis, which is part of a long-delayed series of official climate reports. "At the same time," he added, "we all need to be looking at how the administration now intends to use the results of this information, because it really is worrisome."
The researchers said that of 1,598 animal species examined in more than 800 studies, nearly 60 percent were found to have been affected by climate change.
In addition, the number and frequency of forest fires and insect outbreaks are "increasing in the interior West, the Southwest, and Alaska," while "precipitation, stream flow, and stream temperatures are increasing in most of the continental United States" and snowpack is declining in the West.
The Agriculture Department, the study's lead sponsor, issued a statement yesterday highlighting some of the report's findings for farmers, noting that the higher temperatures mean that grain and oilseed crops will mature more rapidly but face an increased risk of failure and "will negatively affect livestock."