The ice-pack runoff from Oregon's Cascade Mountains powers the state's hydroelectric plants and irrigates its pear orchards. Those ice packs have shrunk by 30 percent or more in the past 50 years, and state officials believe auto exhaust deserves much of the blame.

Regulators in Connecticut think carbon dioxide in auto exhaust threatens maple syrup production and the skiing industry, and they fear what rising sea levels would do to real estate values along the state's coastline if the planet's temperatures continue to rise.

On Friday, Massachusetts joined Oregon, Connecticut and five other states in adopting California's tough greenhouse gas rules, which limit the amount of carbon dioxide and other gases that can be emitted from vehicle tailpipes. These new rules would supplement federal exhaust pollutant standards already in place. Two other states are in the process of adopting the rules.

The carbon dioxide regulations are so strict, the auto industry argues, that they would cause extensive design changes to new vehicles, driving up prices and crippling new-car sales. Every major automaker that sells vehicles in the United States is suing to have the new rules overturned, even as states on the West Coast and in the Northeast are moving quickly to adopt them.

The California rule -- which was approved by a state environmental board in 2004 and, with federal approval, would take effect for the 2009 model year -- requires a 30 percent reduction in greenhouse gases by 2016. The rules are one element of a wider trend of states enacting their own energy policies to govern auto and factory emissions and appliance energy efficiency, updating older federal rules or writing new rules where none exist.

Automakers are countering with a proposed 10 percent reduction in carbon dioxide emitted in vehicle production by 2012. They have not supported restrictions on carbon dioxide emissions from vehicle tailpipes.

If the California rules were in effect today, automakers claim, only a handful of vehicles could meet the test. Gloria Bergquist, vice president of public affairs for the Alliance of Automobile Manufacturers, which leads the lawsuit, said the rules are too burdensome and costly. "There would be marketplace chaos if each state were deciding which products should be sold within its borders," Bergquist said. The suit was filed in federal court in California in December 2004.

State regulators say they are taking the initiative because the federal government, including the Environmental Protection Agency, has been slow to act. They worry that their efforts may ultimately be blocked at the federal level. Also, several state regulators said they are fearful that Congress may use a forthcoming study by the National Research Council to limit states' ability to join the California program. The study is due later this month.

In a statement, the EPA said it favors other methods of lowering carbon dioxide besides regulating tailpipe emissions, siding with automakers that the changes will limit consumer choice and raise vehicle prices.

"The only way to cut [carbon dioxide] emissions is through a drastic increase in fuel economy -- which in the past has led to smaller, lighter and less-safe vehicles," the EPA said in the statement.

The EPA's position is crucial because it would have to issue a waiver before any of California's greenhouse gas regulations could go into effect. If California is permitted to impose the new regulations, the federal Clean Air Act allows other states with poor air quality to adopt California's rules after agency approval.

Scientists say a great deal of carbon dioxide can be absorbed in the atmosphere, but many worry that people are adding more than nature can handle. They say the gases are building up like a heavy blanket surrounding the Earth, trapping heat and raising the planet's temperature.

he confrontation over the California rules is one of the biggest air-quality fights in years. Environmentalists consider the regulations a landmark in their campaign against global warming. The conflict has brought together a number of players. State regulators have banded together and are closely monitoring developments in Washington. Environmental organizations have been building coalitions with health-focused and faith-based groups. Activists have initiated protest campaigns against Toyota Motor Corp. and Ford Motor Co., two automakers that have heavily promoted themselves as being environment-friendly and are parties to the suit.

Vehicle emissions are the No. 2 -- and fastest-growing -- source of greenhouse gases, after power plants, a number of scientists and regulators say.

"For greenhouse gases, the federal government hasn't taken any action at all, and California has," said Andrew Ginsburg, Oregon's air quality administrator. "It's clear the federal government won't do it unless California paves the way and enough other states opt in."

Oregon's decision to adopt the California rules is temporary. Ginsburg said he expected permanent approval to come by summer.

Gina McCarthy, commissioner of Connecticut's Department of Environmental Protection, said states are growing increasingly concerned with fluctuations in temperature but lack tools to deal with the problem.

McCarthy said Connecticut has sought to lower emissions by buying hundreds of hybrid cars and eliminating the sales tax on hybrids sold in the state.

"If you look at greenhouse gas emissions, we can log what's coming from households and business sectors," McCarthy said. "The area where it continues to grow is the transportation sector as people travel more and more and there are heavier, less-fuel-efficient cars on the road. It's a growing concern because states have so little ability to impact that."

California, once again, is leading the charge. The state began regulating air quality in the 1960s. Since then, the state has steadily pushed ahead with tougher clean-car regulations, angering the auto industry along the way. In the 1960s and 1970s, California advocated adoption of the catalytic converter, a now-ubiquitous device bolted underneath vehicles that breaks down most toxins before they hit the air. In the 1990s, the state's regulations sparked engineering and technical innovations that led to the development of today's gas-electric hybrid cars.

Environmentalists say they fear that the rest of the world is passing the United States by adopting tougher standards. Steve Hinchman, staff attorney a the Boston-based Conservation Law Foundation, said the United States is in danger of becoming a "technological backwater" by not acting.

"The whole world is moving. Canada, Europe, China, Japan, Korea, India are all adopting more stringent standards," he said. "We are going to become the dumping ground for the dirtiest cars made in the world. China will have more stringent standards than the U.S. in 2010. That's only a few years away."