WASHINGTON — Once a skeptic about climate change, Jim Bridenstine came around to the prevailing view of scientists before he took over as NASA administrator. That evolution did not sit well with a Trump environmental adviser, nor a think-tank analyst he was consulting, according to newly disclosed emails that illustrate how skepticism of global warming has found a beachhead in the Trump White House.

"Puzzling," says the May 2018 exchange between William Happer, now a member of President Donald Trump's National Security Council, and Thomas Wysmuller of the Heartland Institute, which disavows manmade climate change. Their exchange calls scientifically established rises in sea levels and temperatures under climate change "part of the nonsense" and urges the NASA head — who was copied in — to "systematically sidestep it."

It cannot be discerned whether it was Happer or Wysmuller who put that pressure on the new NASA chief. Their exchange is included in emails from 2018 and 2019 that were obtained by the Environmental Defense Fund under the federal Freedom of Information Act and provided to The Associated Press.

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But the emails show that Happer, who was then advising Trump's Environmental Protection Agency, kept up the pressure after he joined the National Security Council late last year.

In February, he emailed NASA deputy administrator James Morhard, relaying a complaint about NASA's websites from an unidentified rejecter of man-made climate change. "I'm concerned that many children are being indoctrinated by this bad science," said the email that Happer relayed. (Happer's own message was redacted from the records obtained by the environmental group.)

NASA does not appear to have buckled under such heat. Specific statements targeted in the email still appear on the space agency's website.

A NASA spokesman on Thursday upheld the space agency's public statements on climate change.

"We provide the data that informs policymakers around the world," spokesman Bob Jacobs said. "Our science information continues to be published publicly as it always has."

Heartland Institute spokesman Jim Lakely said in an email that NASA's public characterization of climate change as man-made and a global threat "is a disservice to taxpayers and science that it is still pushed by NASA."

The institute is one of the most vocal challengers of mainstream scientific findings that emissions from burning coal, oil and gas are damaging the Earth's atmosphere.

Since joining the National Security Council, Happer tapped two analysts with the institute to help him frame challenges to widely accepted scientific findings on global warming, the emails show.

In a March 3 email exchange, Happer and Hal Doiron, another policy adviser to Heartland, discuss Happer's scientific arguments in a paper attempting to knock down the contributions of fossil fuel emissions in climate disruption, as well as ideas to make the work "more useful to a wider readership." Happer writes he had already discussed the work with another Heartland adviser, Wysmuller.

Academic experts denounced the administration official's continued involvement with groups and scientists who reject what numerous federal agencies say is the fact of man-made climate change.

"These people are endangering all of us by promoting anti-science in service of fossil fuel interests over the American interests," said Pennsylvania State University climate scientist Michael Mann.

"It's the equivalent to formulating anti-terrorism policy by consulting with groups that deny terrorism exists," said Northeastern University's Matthew Nisbet, a professor of environmental communication and public policy.

The National Security Council declined to make Happer available to discuss the emails.

The AP and others reported this year that Happer was coordinating a proposed White House panel to challenge the findings from scientists in and out of government that carbon emissions are altering the Earth's atmosphere and climate.

Trump in November rejected the warnings of a national climate change assessment by more than a dozen government agencies.

"I don't believe it," he said.

Happer, a physicist who previously taught at Princeton University, has claimed that carbon dioxide, the main heat-trapping gas from the burning of coal, oil and gas, is good for humans and that carbon emissions have been demonized like "the poor Jews under Hitler."

The emails show Happer expressing surprise that Bridenstine, a former Oklahoma congressman, had put his skepticism of global-warming science behind him before becoming NASA chief in April 2018.

Bridenstine a year ago told reporters that after reading Defense Department briefings on global warming, he became convinced it is a serious national security problem: "We're defending territory in the Arctic that we never had to defend. The Russians are doing things in the Arctic that they never used to be able to do."

He said no other agency has NASA's credibility when it comes to studying climate change and helping policymakers form decisions about it.

Two major U.S. science organizations took issue with Happer's emails.

"We have concerns that there appear to be attempts by a member of the National Security Council to influence and interfere with the ability of NASA, a federal science agency, to communicate accurately about research findings on climate science," said Rush Holt, chief executive officer of the American Association for the Advance of Science, the world's largest general scientific society.

Hundreds of scientific assessments by leading researchers and institutions the last few decades have looked at all the evidence and been "extremely credible and routinely withstand intense scrutiny," said Keith Seitter, executive director of the American Meteorological Society.

He said efforts to dismiss or discredit such assessments are "an incredible disservice to the public."