How the White House is dismantling the heart of US climate policy

“Thank you for your participation in the 6th National Climate Assessment. At this time, the scope of the NCA6 is currently being reevaluated in accordance with the Global Change Research Act of 1990. We are now releasing all current assessment participants from their roles. As plans develop for the assessment, there may be future opportunities to contribute or engage. Thank you for your service.”

This was the email that landed April 28 in the inboxes of the nearly 400 scientists who were contributing to the latest National Climate Assessment (NCA), the congressionally mandated review of how global warming impacts the US. One of these scientists was Elizabeth Koebele, an environmental social scientist at the University of Nevada, Reno. She was at home, trying to get work done on a grant proposal.

“It was the middle of the afternoon when I got the email,” says Koebele, who was one of the chapter leads for the sixth NCA, due out in 2028. Thirteen US agencies work with the scientist-authors over several years to produce each assessment, which draws upon the most up-to-date research to report on current and projected climate conditions in the US.

Koebele had been chipping away at the massive assessment for over 6 months—coordinating with the federal employees at the US Global Change Research Program (GCRP), searching out other volunteer scientists to contribute to the report, and generally reading and sending a lot of emails.

But she was not expecting the email that dismissed her. “We knew that things were challenging and staff were being laid off” but didn’t think that all the authors would be released, she says. The email was so short and blunt that Koebele was sure she’d get a follow-up from a trusted source about it. But that never came. Instead, Koebele turned to the social network Bluesky and quickly found that many other authors were posting about it there, likewise surprised and dismayed.

The Donald J. Trump administration has said no more since then about the next NCA, but it has taken multiple actions that seem to undermine evidence that climate change is a threat to human health and welfare and to remove this evidence from government websites.

On June 30, the website for the GCRP—the federal entity that coordinates government research on climate change—went dark. All past versions of the NCA hosted on the website went with it. Also on June 30, the US Environmental Protection Agency (EPA) asked the White House Office of Management and Budget to reconsider a key 2009 scientific finding that greenhouse gas (GHG) emissions endanger human health, known as the endangerment finding. And on July 8, the New York Times broke the news that the US Department of Energy (DOE) had hired three scientists known for their climate change–denialist stances.

Scientists and environmental advocates say that these actions aren’t isolated incidents. Along with the release of the NCA authors, they add up to an attempt by the Trump administration’s EPA to stop regulating GHGs altogether.

On March 12, EPA administrator Lee Zeldin announced the government’s intention to reconsider the endangerment finding, which he called the “holy grail of the climate change religion.” Issued by the EPA during Barack Obama’s administration, the endangerment finding is the scientific and legal foundation for the EPA to regulate GHG emissions under the Clean Air Act. It essentially says that because GHGs contribute to climate change, they are harmful to people and should be regulated.

Striking down the endangerment finding would mean that GHGs could no longer legally be regulated by the federal government, since regulations that rely on the finding would no longer be valid. To fully free GHGs from regulatory constraints, each of the laws and rules would still have to be rescinded.

The EPA really has only two legal ways of rescinding the endangerment finding, according to Andy Miller, former senior science adviser for the EPA’s Office of Research and Development. One method is to ask Congress to change the Clean Air Act to say that GHGs are not pollutants. This is the harder road and unlikely to be successful, Miller says. The other way is to show a solid scientific basis for overturning the finding.

“The endangerment finding is based on what’s called a highly influential scientific assessment,” Miller says. Under government rules, agencies making such assessments must cite research with a solid scientific basis. So to overturn the endangerment finding, the EPA would have to say it has new science that invalidates the previous science that supported the finding, Miller says, or that past research was somehow inappropriate or not robust. But by the same government rules, any new science also must be built on a solid scientific basis.

“Zeldin has said that [the EPA] plans to go through notice and comment to revoke the endangerment finding,” says Jeff Holmstead, former assistant administrator of the EPA Office of Air and Radiation and now a lawyer at the firm Bracewell. That means the EPA would have to get a lot of information and data together and “then write up a proposal that says, ‘Upon further reflection and looking at these other things, we believe that it was incorrect to say that greenhouse gas emissions from motor vehicles or from other US sources are reasonably anticipated to endanger public health and welfare,’” Holmstead says.

In essence, the EPA would have to produce a new mini NCA.

The agency would have to put this proposal up for public review for the legally required amount of time, Holmstead says. “Then they would issue a final rule that revokes the endangerment finding more broadly, that in and of itself could be challenged,” he says.

According to the White House Office of Information and Regulatory Affairs’ online schedule, Office of Management and Budget meetings about the EPA’s proposed reconsideration of the endangerment finding started on July 10 and are ongoing.

In the past, the NCAs have been used to support the endangerment finding because they provide the solid scientific evidence the government requires, Miller says. But with the release of Koebele and the other authors in April, the future of the NCA is up in the air. Scientists and environmental activists worry about what scientific evidence the Trump administration might turn to instead of the NCA.

“What will fill in the void? Will the Trump administration turn to junk science?” says Melissa Finucane, vice president of science and innovation at the Union of Concerned Scientists, a science advocacy group.

Legally, the government has to produce an NCA. The Global Change Research Act of 1990, a US law that requires the government to research climate change, includes a mandate to create the report. But the timetable is malleable, Miller says. “The requirement is to produce a report every 4 years to the president and Congress,” he says. “But we’re now, what, 35 years after the passage of the act and we’re now on the sixth climate assessment? So it’s clearly not every 4 years.”

In theory, the Trump administration could not put out an NCA at all. But just not issuing one doesn’t help overturn the endangerment finding, Holmstead from Bracewell says. “If they convened a new group and that group were to draft an NCA that somehow concludes that greenhouse gas emissions are not reasonably anticipated to endanger public health or welfare, then that would be a step towards revoking the 2009 endangerment finding,” he says.

Miller agrees. “If they were not to do a new NCA, then the scientific record would not change,” he says. “But if they do a new one from their perspective, they have something new to point to.” Miller suspects that the Trump administration will release a report that reflects its policy preferences. And the DOE’s recent engagement of three climate change–denial scientists suggests the administration is moving in that direction, he says.

Many scientists and environmental advocates fear such a revisionist NCA. “They could do some reckless stuff with it by subverting the intent and making it kind of a splashy climate denialist version of the assessment report,” says Dustin Mulvaney, an environmental scientist at San José State University and one of the released authors.

In the past, the NCAs have varied significantly in scope and depth, the Union of Concerned Scientists’ Finucane says. But this time is different, she says. “Any resumption of the climate [assessment] process will be perceived to be a political rather than a scientific endeavor,” Finucane says. Because of that, the credibility of the NCA takes a hit, “and it could be a lasting hit.”

Working against a revised NCA is the fact that the GCRP would have a hard time gathering enough authors to write a scientific assessment concluding that GHGs don’t endanger public health or welfare, Miller says. “There are only a few people who have scientifically robust enough backgrounds that would be appropriate that could even pass a laugh test in terms of authorship,” he says.

The new report would need reviewers too. “You have to have a separate group of people who will do a review of this document if you’re going to follow the rules,” Miller says. And very few people with the right scientific background would be willing to stand up and say that all the NCAs to date were wrong, he says.

But the damage could go beyond issuing a report at odds with the scientific consensus on climate change, he says. “I think that the damage is that this is the process now. In some ways, the report doesn’t matter anymore,” Mulvaney says. The spectacle of the administration dismissing the NCA authors and showing that it has the power to stop scientific reports is the goal, he says.

Representatives from the US government offices that oversee the NCA—the Office of Science and Technology Policy and the GCRP—did not respond to requests for comment.

No matter what kind of NCA the government might produce, whether or not it happens during this administration is in Congress’s hands, says Joseph Brazauskas, senior counsel at Bracewell.

“It’s up to Congress to enforce and oversee the directive that’s given to the federal government,” he says, to the extent that Congress indicates it ought to happen, appropriates funds, and ultimately authorizes the funds needed to complete the assessment. “The way that Congress has written this bill, this law, essentially, is that it gives the discretion to the federal government to choose the members of the council” and other overseeing members however they choose to, he says.

But if Congress does not demand that the sixth NCA be delivered in 2028, there’s no other authority that can. “I am not aware of any sort of legal mechanisms that would allow a group outside of Congress to try to enforce completion of [the NCA], to live up to the standards of this,” Brazauskas says.

None of the members of the House or Senate science committees responded to repeated requests for comment about enforcing the mandate to do the assessment.

As for Koebele, she has hope that she can still work on the sixth NCA. “The email did say that there might be potential for us to re-engage,” she says. “So if there is a point where NCA6 is revived, and it maybe has a slightly different scope, I know that several of my chapter authors and I are anxious to stay engaged with the process.”