OS ANGELES, July 16 — In a letter that attacks what it says is the Bush administration's failure to address the looming crisis of global warming, the attorneys general of 11 states have written to the president pressing for strong federal measures to limit emissions of so-called greenhouse gases.
The state officials argue in the letter, to be sent on Wednesday to President Bush, that his administration's "regulatory void" has left it to the states to piece together a patchwork of inconsistent regulations on the environment and that a strong federal policy would be far more effective.
The letter was written as Gov. Gray Davis of California was scheduled to sign a bill on Monday intended to reduce emissions of heat-trapping gases like carbon dioxide. Mr. Davis's approval of the bill, which would require automakers to sell more fuel-efficient cars, had been widely expected since the Legislature passed it. The passage, despite strong opposition from the automobile industry, could prod additional states to take similar measures, because California has by far the largest automobile market in the nation.
The officials sending the letter to Mr. Bush, all Democrats, indirectly criticized him for saying that the science on global warming had not conclusively proved its existence. The officials cited a report that the administration issued in May, saying it justified strong action to avoid potentially devastating consequences to the environment and public health.
"For these reasons," the officials said, "we write today to urge you to reconsider your position on the regulation of greenhouse gases and to adopt a comprehensive policy that will protect both our citizens and our economy."
The letter was spearheaded by the attorney general of Massachusetts, Thomas F. Reilly. It was also signed by the attorneys general of New York, Connecticut, New Jersey, California, Alaska, Maine, Maryland, New Hampshire, Rhode Island and Vermont.
The letter also contended that the administration's environmental policies had made problems worse.
"Far from proposing solutions to the climate change problem, the administration has been adopting energy policies that would actually increase greenhouse gas emissions," it read.
A spokeswoman for the White House, Claire Buchan, noted that the National Governors' Association last year and the state environmental commissioners in 2000 rejected calls for mandatory reductions in carbon dioxide emissions.
"The president is working on a bipartisan common-sense approach," Ms. Buchan said.
Mr. Bush's Clear Skies initiative, she said, "would lead to the largest reduction in power plant emissions ever."
The principal greenhouse gas is carbon dioxide, which automobiles, as well as power plants and numerous industries, release into the air. The carbon dioxide retains heat from the sun in the atmosphere, rather than letting it dissipate, contributing to a slow rising of temperatures.
Scientists have shown that the warming, although measured in just a degree or two on average in some places, has already had effects like allowing a proliferation of insects to destroy spruce forests in Alaska and raising the average levels of the oceans. The scientists warn that the warming, if unchecked, could flood coastal areas, disrupt water supplies, cause heat waves and destroy some wetlands and coral reefs while increasing problems from insect-borne diseases.
The amount of carbon dioxide in the atmosphere was relatively constant for 400,000 years, experts say. But with the industrial revolution 150 years ago, it has soared. Carbon dioxide has an unusually long life in the atmosphere, so even with drastic action, experts say, it could take years for Earth to begin cooling again.
In an interview, Mr. Reilly, the Massachusetts attorney general, criticized Mr. Bush's dismissal of the science on global warming and said there was a new sense of urgency.
"You can't ignore this any longer," he said. "This is not something you can fool around with. The kind of brushoffs we've gotten from the administration are kind of offensive."
David Samson, the attorney general of New Jersey, added that global warming "poses real and immediate dangers to New Jersey's environment and the health of our citizens."
The authors do not specify what they want, but Mr. Reilly said they were seeking at the least caps on the carbon dioxide that power plants emit, as well as increases in average mileage standards for automobiles.
The authors suggest so-called market-based policies. Under such programs, which are used in a number of industries that produce large volumes of gas emissions, companies can profit from lowered emissions by selling their emission "rights" to other companies that produce more gases. The extra costs and the potential profits give companies an incentive to cut back. Conservatives have embraced such market-driven policies in many instances.
"The letter is one that ought to receive a lot of sympathy in the Bush administration," Richard Blumenthal, the attorney general of Connecticut, said, "because it calls for a market-based approach to capping the total greenhouse gases and allocating credits to industries and companies to buy and sell. It's a very Republican approach."
In addition to the action by the California Legislature, a few other states, including New York, are moving in the direction of limiting carbon emissions.
According to the Natural Resources Defense Council, an environmental group, automobiles produce 25 percent of the carbon dioxide emissions in the country and power plants produce 40 percent.
