A federal appeals court on Tuesday upheld the Environmental Protection Agency’s finding that greenhouse gases contribute to global warming and are a threat to public health, a major victory for the Obama administration and a setback to states and trade groups that oppose government regulations on carbon emissions.

The opponents, including Virginia’s attorney general, Ken Cuccinelli II (R), argued that EPA rules setting emissions standards for cars and light trucks, and requiring construction and operating permits for the nation’s largest emitters of greenhouse gases, such as coal-fired power plants, were based on a faulty interpretation of the Clean Air Act, and therefore capricious and heavy handed.

But in a sharply worded opinion, the U.S. Court of Appeals for the District of Columbia Circuit rejected the challenge to the agency’s authority, saying the EPA’s “interpretation of the . . . Clean Air Act provisions is unambiguously correct.” It said the EPA’s rules targeting large polluters could not be challenged because of the authority granted the agency in an earlier Supreme Court ruling.

In its remarks, the three-judge panel seemed to bristle at the opponents’ argument that the EPA improperly relied on assessments of climate science by the Intergovernmental Panel on Climate Change, the National Research Council and the U.S. Global Change Research Program to support its findings that greenhouse gases contribute to warming, posing a threat to human health.

“This argument is little more than a semantic trick,” the opinion said. “EPA did not delegate . . . any decision-making to any of those entities. EPA simply did here what it and other decision makers often must do to make a science-based judgment.

“This is how science works. EPA is not required to re-prove the existence of the atom every time it approaches a scientific question,” the court said.

The unanimous decision covered dozens of suits bundled together under a group called the Coalition for Responsible Regulation. Cuccinelli vowed to appeal the agency’s interpretation of the act and its endangerment finding to the Supreme Court.

“I do not believe the Supreme Court intended to compel such a destructive interpretation of the Clean Air Act” in the court’s earlier ruling, he said.

EPA Administrator Lisa P. Jackson called the ruling “a strong validation of, in the court’s own words, the ‘unambiguously correct’ approach we have taken in responding to the 2007 Supreme Court decision.”

In that decision, the high court ruled that the EPA was obligated under the Clean Air Act to clarify whether greenhouse gases were an air pollutant, and regulate them if they were. The agency subsequently determined that the gases constituted a pollutant and a danger to public health, and issued an emissions rule for cars and some trucks.

The agency also determined that stationary facilities, such as coal-burning power plants, should obtain permits for operations and additional construction. To avoid overburdening the industry with permits, the EPA issued “timing and tailoring rules” that first targeted the largest polluters.

Texas, Nebraska, North Dakota and Alabama joined Virginia in opposition. The EPA’s supporters included New Mexico, New York, Massachusetts and Oregon.

Tuesday’s ruling gave the EPA “a green light to keep moving forward” on a second round of vehicle emissions and a proposed nationwide emission standard for new power plants, said David Doniger, a senior attorney for the Natural Resources Defense Council, an environmental advocacy group.

Organizations such as the Electric Reliability Coordinating Council that represent power plants have protested the permitting requirements. They said it will cost billions of dollars and put thousands of jobs at risk.

The court said the EPA’s endangerment finding — that human activity increases greenhouse gases that trap heat on earth that would otherwise go into space, and that it warms the climate — was supported by substantial evidence.

“I am pleased that the [court] found that EPA followed both the science and the law in taking common-sense, reasonable actions to address the very real threat of climate change by limiting greenhouse gas pollution from the largest sources,” Jackson said.

Policy analysts and environmentalists who side with the EPA lined up to praise the ruling.

The Environmental Defense Fund called it “a huge win.” Paul Bledsoe, senior adviser at the Bipartisan Policy Center, said the ruling means “greenhouse regulation is bombproof under the law.”

But Nick Loris, a Heritage Foundation fellow, said the regulations will result in “higher energy costs and a slower economy — all for no noticeable change in the earth’s temperature.”