Donald Trump’s victory in the presidential election shocked climate scientists and policymakers after a campaign in which Trump had suggested—falsely—that climate change was a hoax and vowed to largely undo federal and international measures aimed at addressing global warming.

Nonetheless, climate advocates took solace in the days following the election, noting that the market forces largely responsible for the shift away from coal and the incontrovertible science supporting climate regulations would remain true regardless of who was President. But in the six weeks since the election, Trump’s transition team has suggested that the incoming administration will not simply challenge the Obama administration’s policies but will also launch an attempt to undermine the years of science underpinning them. Such an effort could have major implications for the credibility of U.S. government data—and the ability of the world to fight global warming.

“It’s very damaging because it undermines the public confidence in scientists and government,” says Christine Todd Whitman, who served as EPA administrator under George W. Bush from 2001 to 2003, of Trump’s approach to science. “When you start to undermine that public confidence, it can have long-term damaging consequences.”

Trump is still more than a month from taking office, but his team has already sought to undermine basic facts on energy and environmental issues in a number of agencies using a variety of means. Senior Trump adviser Bob Walker said in November that the incoming administration would eliminate NASA’s Earth sciences division, calling its work “politicized.” That department operates satellites to monitor the Earth’s climate and provides data on the changing atmosphere.

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The transition team sent a questionnaire to the Department of Energy asking for the names of individuals who worked to calculate the social toll carbon dioxide takes on the atmosphere or attended United Nations climate conferences, stoking fears that career staffers might lose their jobs for working on climate issues. Trump’s choice to lead the agency—former Texas Governor Rick Perry—has described the science of climate change as an open question. The Trump transition team told TIME that the questionnaire was “not authorized” and the sender had been “counseled.” (The transition team did not respond to other questions for this article).

Officials at the non-partisan Energy Information Administration (EIA) were asked if their data had been subject to political influence during the Obama years. That is, Trump’s team asked whether the EIA—a federal agency that tracks and makes forecasts in the energy industry—presented too rosy a view of the growth of renewable energy while discounting coal to encourage renewable investment. This accusation, described as “nonsense” by Rosenberg, was particularly surprising given the high regard to the agency across the aisle and in the energy industry with oil, gas, coal and renewable companies alike.

These steps by Trump’s team represent a dramatic escalation in fights over energy and environmental policy. Many Republicans—think President George W. Bush—have acknowledged the science of climate change while arguing that certain demands from environmentalists would damage the economy. That conclusion is still grounded in a belief and respect for science, no matter how much it might frustrate green advocates.

“People can come to different conclusions about what society should do in light of the evidence in front of them—natural sciences, social sciences, public sentiment and so on,” says Andrew Rosenberg, Director of the Center for Science and Democracy at the Union of Concerned Scientists. “People here are saying, ‘we don’t care what that scientific evidence is, we know better’ or they’re trying to directly corrupt the scientific evidence by attacking the scientists.”

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But in 2016 disputing the fundamentals of science may be the only way Trump can enact an agenda that disregards climate change. Policymaking—particularly with rules issued by agencies like the EPA—requires troves of evidence from a variety of disciplines to back it up. Reversing the slew of Obama-era policies will require agencies to come up with a scientific justification, something that is increasingly difficult as the science of climate change becomes more clear by the day. But if the Trump administration tosses decades of data and federal research or only seeks advice from industry the policy rationale for reversing regulations becomes legally defensible.

“Just as you have 97% of scientists who say climate change is real and humans have an impact on it, you can find the other 3% who say, ‘no it’s not happening,'” says Whitman, explaining how a Trump administration could enact its agenda. “You can find people who say no and then that’s all you listen to.”

Whitman, who quit the Bush administration because she felt that her agency had been hampered, said that indications from the incoming Trump administration suggest it will be far worse.

One of Trump’s first targets—and one of the most challenging ones—will likely be Obama’s Clean Power Plan. Obama described the measure, which pushes states to shift away from coal-fired power plants, as the most significant step the U.S. has taken to combat climate change. The rule, the product of years of study and litigation, is justified on the basis that greenhouse gas emissions endanger public health and, therefore, need to be regulated by the EPA. The so-called endangerment finding was upheld in federal court. If Trump were to get rid of the Clean Power Plan, he would need to replace it with something else—unless he gets rid of the endangerment finding. And the only way to do that would be to rethink years of scientific research.

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Scientists have responded to Trump’s statements with increasing alarm. Some have begun downloading government data onto independent servers fearing that the incoming administration might remove it from the public domain. Others have begun to reframe crucial research as a matter of jobs rather than environmental concerns.

Of course, it remains early days. Trump is yet to take office and could yet offer a radical shift in direction. Maybe his daughter Ivanka or another meeting with Al Gore will change his mind. Or maybe he will just operate as a replica of Bush. “Anybody who says they know what’s going to happen is reading out of a broken crystal ball,” says Jonathan Levy, who served as deputy chief of staff in the Department of Energy.

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Write to Justin Worland at justin.worland@time.com.