The Bush administration could be forced to take action on global warming using a 30-year-old piece of legislation to control the nation's vast emissions of greenhouse gases.
The US Supreme Court will today be asked to force the government to order its environmental regulatory body to control, as a matter of the public health, the amount of carbon dioxide pumped out by vehicles.
Amid a growing disparity between the Bush administration and many US states on the issue of global warming, it will be the first time the country's highest court has heard a case relating to climate change.
A number of environmental groups have joined with a dozen US states and several cities to try to force the government to make the Environmental Protection Agency (EPA) regulate carbon emissions under the framework of the Clean Air Extension Act. This legislation, passed by Richard Nixon's administration in 1970, requires the EPA to develop and enforce regulations to protect the public from exposure to airborne contaminants.
The Bush administration has argued that the EPA lacks the authority under the act to regulate CO2 as a pollutant. The agency has argued that even if it had the authority, it would still have the discretion not to impose emission controls.
Carbon dioxide is one of the main greenhouse gases pumping into the atmosphere that a broad majority of scientists believe are responsible for raising the planet's temperature. The Intergovernmental Panel on Climate Change has concluded that most of the planet's warming over the past 50 years has been the result of human activity.
The US, with 5 per cent of the world's population, is responsible for 25 per cent of greenhouse gas emissions and accounts for 37 per cent of the world's vehicles. The Bush administration has repeatedly refused to agree to limits on emissions, saying it would damage the economy. It has instead proposed developing better technology to limit emissions. One of the first things George Bush did on taking office in 2001 was to signal that the US would not support the Kyoto treaty.
A divided lower court had ruled in favour of the government in this test case, but the Supreme Court has agreed to a request, filed by the State of Massachusetts, to consider an appeal.
The Massachusetts attorney general, Thomas Reilly, said "global warming is the most pressing environmental issue of our time and the decision by the court on this case will make a deep and lasting impact for generations to come".
In his filing to the court, he added: "Delay has serious potential implications. Given that air pollutants associated with climate change are accumulating in the atmosphere at an alarming rate, the window of opportunity in which we can mitigate the dangers posed by climate change is rapidly closing."
In papers filed with the Supreme Court, the government has argued that the EPA should not be required to "embark on the extraordinarily complex and scientifically uncertain task of addressing the global issue of greenhouse gas emissions" when there were other ways to tackle climate change.
The Associated Press reported that James Connaughton, chairman of the White House Council on Environmental Quality, told reporters: "We still have very strong reservations about an overarching, one-size-fits-all mandate about carbon."
The government is being supported by a number of industry groups representing car makers and manufacturers. Quentin Riegel, a lawyer with the National Association of Manufacturers, said dealing with climate change required a global response that was enforced fairly. "It's not a problem you can solve unilaterally," he said. "We want a system where everyone shares the burden."