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Several vehicles exit I-270 onto York St. just before I-76 on November 2, 2025 in Denver, Colorado. The Colorado Department of Transportation website describes the purpose of the proposed I-270 Corridor Improvements project is to implement transportation solutions that modernize the I-270 corridor to accommodate existing and forecasted transportation demands. (Kathryn Scott, Special to The Colorado Sun)

The Trump EPA’s Thursday repeal of an Obama-era “endangerment finding” that allowed federal regulation of greenhouse gases from vehicles and other sources will set back Colorado air pollution efforts, but progressive environmental groups and supportive state officials vowed to “play the long game” to restore key controls. 

Repealing the EPA’s right to set greenhouse gas controls was a long-stated target of GOP politicians and conservative business groups, who find the regulations excessive and question the practicality of slowing global warming. The immediate impact of negating the 2009 endangerment finding will be a further unleashing of car and truck manufacturers to sell more gas-guzzling and high-emitting vehicles, Colorado leaders said, reversing years of progress in transforming the state’s fleet to clean engines. 

In a broader sense, Colorado environmental groups said, the announcement was a long-expected national surrender on greenhouse gas and climate change issues they’ve worked on for decades. 

“While the Trump administration moves to repeal the legal foundation of federal climate regulation, the reality of climate change is impossible to ignore,” said Erin Overturf, clean energy director at Western Resource Advocates. “In Colorado we are experiencing an unnervingly warm winter and record low snowpack, further exacerbating drought and wildfire risks. In the face of federal abdication, state action has never been more important. We will continue to ensure Colorado’s leaders drive policies to reduce emissions and adapt to our new challenges — we can’t leave our communities laid bare to the forces of climate change.”

“Latino communities are on the front lines of climate disasters and air pollution. The science is clear, the insurance companies are reflecting the disaster payouts in their rates, farmers know their yields are changing and the water shortages continue,” said Ean Tafoya, vice president of state programs for GreenLatinos, in an email response. “Dismantling this safeguard is reckless, dangerous, and morally indefensible.”

There will be an impact on Colorado, state Energy Office executive director Will Toor said. 

Thursday’s move, announced from the White House, “means that all forms of pollution associated with vehicles are going to be worse,” Toor said, in an interview. “And in a world where a significant portion of the people who live in Colorado live in an area that doesn’t meet federal ozone standards, rolling back vehicle pollutant standards makes no sense. In a world in which climate change is directly affecting Coloradans today. The fact that this weekend I was able to be walking in shorts in February gives a sense of the sorts of impact that we’re seeing. All anybody has to do is look at the state of the Colorado River and the impact on our water supply to understand what climate change is already doing to Colorado.” 

The endangerment finding previously bolstered federal efforts to lower greenhouse gas and local pollutant emissions from cars and trucks nationwide, and to promote or force the conversion of the national vehicle supply to clean electric models. 

Colorado’s effort to get more electric vehicles on the road, with about 200,000 now in the statewide total of millions of cars and light trucks, was already under serious threat. The GOP-controlled Congress had previously canceled waivers given to California’s clean cars and clean trucks plans, and Colorado joined California in suing to preserve those rules. 

The endangerment cancellation calls into question the larger framework of EPA and Department of Transportation minimum mileage standards for fossil fuel cars. 

Many conservative interests applauded the White House announcement. 

“This action is long overdue and good for the American people, freeing up the auto industry to make the vehicles people want unburdened by unnecessary emission restrictions or money-losing electric vehicle mandates,” said H. Sterling Burnett, director of the Arthur B. Robinson Center for Climate and Environmental Policy at the conservative nonprofit The Heartland Institute. “Today is a win for car and truck buyers and Trump should be applauded for taking this action. The endangerment finding was never justified by either science or law. Now it’s time to strike another blow for affordability, and strike while the iron is hot, to rescind endangerment for power plants as well.”

There will be state and environmental lawsuits challenging Thursday’s move, Toor said.

“We certainly believe that in addition to being an action that will drive up costs for consumers and make the air dirtier and worsen climate change, that it is also not legally sound, and I certainly anticipate that we will see multiple entities litigating on this,” he said. 

Colorado Attorney General Phil Weiser, who is involved in dozens of lawsuits against Trump administration actions on the environment, agency budgets and immigration, immediately vowed to fight. 

“There is no legal or scientific justification to roll back decades of progress in fighting climate change by undoing a finding rooted in well-established research and common sense: greenhouse gas emissions from motor vehicles endanger public health and welfare. We live that reality every day in Colorado, with record drought, catastrophic wildfires, and ever-increasing heatwaves that threaten our residents, economy, and infrastructure,” Weiser’s statement said. “The Supreme Court held nearly 20 years ago that the federal Clean Air Act authorizes EPA to regulate greenhouse gas emissions. I will challenge this illegal action in court.”

The Environmental Defense Fund said deregulation of the car and truck industry through repeal of endangerment will mean billions in extra costs to consumers, who otherwise could have switched to EVs that are cheaper to operate. Coloradans will pay more than $19 billion in extra fuel costs by 2055,an EDF analysis said, without even counting the nearly $6 billion in health harms from burning more fossil fuel. 

The Kenworth medium duty battery-electric truck from MHC Kenworth – Greeley, looms large on the showroom floor at the opening day of the Denver Auto Show at the Colorado Convention Center April 12, 2023 in Denver, Colorado. Kenworth describes the truck as having a 200 mile range on its battery and a rapid on-hour DC re-charge, perfect for local distribution, pickup and delivery, and last minute logistics applications. (Kathryn Scott, Special to The Colorado Sun)

The impact of the loss of endangerment protections on other sectors of the economy and air pollution are less clear, Colorado leaders said. The largest single sources of greenhouse gas emissions, as well as tons of other local health-harming pollutants, are fossil fuel electric power plants, each pumping millions of tons of carbon dioxide into the atmosphere in a year. 

“The state of Colorado continues to have our own independent regulation in the power sector, unlike vehicles, where there is federal preemption,” Toor said. 

However, the Trump administration this week expanded its efforts to boost the coal industry and coal-fired power, ordering the Defense Department to negotiate directly with power providers for coal-fired power. Colorado Springs Utilities has said one reason it wants to keep the Ray D. Nixon coal plant burning past a previously planned closure in 2029 is to assure reliability for the many defense installations in El Paso County. 

Environmental groups and attorneys general studying the endangerment ruling still see potential openings to combat the federal reversal. 

“I don’t think that it’s ‘game over’ for the states in terms of regulation of greenhouse gases from cars and trucks,” said David Pettit, senior attorney with the Center for Biological Diversity’s Climate Law Institute. “But the states may have to play the long game to get those protections back.”

The EPA can’t have it both ways, one theory goes — if the agency is saying it shouldn’t have the authority to regulate greenhouse gas emissions from cars because they don’t “endanger” the public, then individual states should be free to do so, Pettit said. 

“And every state can then enact its own car and truck greenhouse gas emissions regulations. That would pose obvious problems for the auto industry and oil industry,” Pettit said. 

“The EPA’s other argument is that whether or not it has the authority to do so, it is choosing in its discretion not to regulate greenhouse gases from cars or trucks,” Pettit said. “If the court decides that EPA’s position is legal, then the states will probably need to wait for another presidential administration where EPA might change its mind again.”

Type of Story: News

Based on facts, either observed and verified directly by the reporter, or reported and verified from knowledgeable sources.

Michael Booth is The Sun’s environment writer, and co-author of The Sun’s weekly climate and health newsletter The Temperature. He and John Ingold host the weekly SunUp podcast on The Temperature topics every Thursday. He is co-author...