Last Thursday, there was a moment when it was possible to hope that Donald Trump’s presidency wouldn't be as ecologically catastrophic as many feared.

As with so many matters of serious policy, Trump’s approach to the environment is difficult to predict, given the paucity of detailed plans he has released, and his tendency to switch positions on a whim. And so, when several of his more extreme campaign promises vanished from his official website, including his vow to withdraw the United States from the Paris Agreement on climate change, I wondered if he’d reconsidered. Perhaps he decided to heed President Obama’s advice. Perhaps he was swayed by China’s grumbling. Or perhaps, the collected works of an entire generation of climate scientists finally persuaded him that it would be foolish to abandon a collective pledge, negotiated by all of Earth’s nations, to reduce greenhouse-gas emissions.

It was a vain hope. Under the terms of the Paris Agreement, no country can withdraw until 2020. But that may not matter much. After all, the president-elect knows how to weasel out of a deal. Trump’s advisers are said to be looking for a loophole, a way to terminate the agreement within his first 100 days in office.

Among those advisers is Myron Ebell, a man who denies, against all evidence, the very possibility that humans are changing the Earth’s climate significantly. “There has been a little bit of warming,” Ebell told Vanity Fair in 2007. “But it’s been very modest and well within the range for natural variability, and whether it’s caused by human beings or not, it’s nothing to worry about.”

If Ebell heads up Trump’s Environmental Protection Agency, as many expect, he will likely be tasked with gutting the Clean Power Plan, the suite of executive orders President Obama signed in order to speed America’s transition to emissions-free energy sources. As my colleague Robinson Meyer reported, even if Trump were to restrict himself to these policies—nixing the Paris Agreement and the Clean Power Plan—crucial ground will be lost in the fight against climate change:

The Intergovernmental Panel on Climate Change estimated that the planet could only stand another five years of emissions at current rates before it would become impossible to keep the global mean temperature from rising 1.5 degrees Celsius. If emissions increased under a Trump administration, as Lux projects, then the world could overshoot that carbon budget well before 2021.

And it is unlikely that Trump will restrict himself to these policies. In fact, there are signs that he could impair our understanding of Earth’s climate. At one point during his campaign, he promised to end American support for UN climate science. And in an October op-ed in SpaceNow, two of Trump’s leading advisers on space policy argued that NASA should cut spending on “politically correct environmental monitoring,” which sucks up a third of the agency’s budget, in favor of human missions to the far edge of the solar system.

Consider, for a moment, the absurdity of this suggestion: that environmental monitoring is motivated by “political correctness.” As though scientists do not have a natural interest in the ebbs and flows of atmospheric chemistry, and the carbon cycle that determines Earth’s climate on long time scales. As though cloud formation, precipitation patterns, sea winds, and hurricanes are incidental to a deep understanding of the physical world. As though we should pay no mind to the frozen poles, or Greenland’s ice sheet, or the glaciers that slip and slide in mountain valleys across the globe. As though we have no stake in the oceans’ plankton blooms, or the health of its coral reefs. As though wildfires and soil moisture are immaterial. As though we do not depend, for our survival, on the good health of the vegetation that greens our continents.

The work of NASA’s Earth Science division is part of an intellectual tradition that precedes so-called “political correctness” by millennia. The experiments that Trump’s advisors dismiss are born of a long empirical march from antiquity, when the Earth was proven round, to the Scientific Revolution, when it was dislodged from the world’s center, to the Enlightenment, when geologists began to grasp its extreme age, on through to today’s satellites and stratosphere-scraping planes, which track the intricacies of its most dynamic systems. The close, patient study of this planet has nothing to do with the passing fashions of political speech in the here and now.

Indeed, it was Ronald Reagan, hardly a slave to political correctness, who signed the space policy directive that made the expansion of “our knowledge of the Earth and its environment” one of NASA’s core missions. A century from now, depending on what happens to our climate, historians may look back on our era through the lens of environmental policy. In which case, Reagan could well look like a climate hawk compared to Donald Trump.