More than five hundred and seventy members of the National Academy of Sciences published a statement on Monday decrying the Trump Administration’s “denigration of scientific expertise and harassment of scientists.” The members, who are acting independently of the N.A.S., represent many fields (social, biological, environmental, physical), but they note that the White House’s “dismissal of scientific evidence” has been “particularly egregious” in the case of climate change. They cite the Administration’s recent effort—led by Scott Pruitt, the head of the Environmental Protection Agency, and supported by President Trump—to hold a “Red Team/Blue Team” debate on the validity of global-warming research. “Such an exercise seeks to foster the erroneous impression of deep uncertainty concerning the reality and seriousness of anthropogenically driven climate change,” they write.

Benjamin Santer, a sixty-two-year-old atmospheric scientist at the Lawrence Livermore National Laboratory, in California, co-authored the statement with Ray Weymann, a retired astrophysicist, and Charles Manski, an economist at Northwestern University. Because Santer’s work is almost entirely funded by the Department of Energy, he now fears losing his job. “There are powerful individuals out there who do not like criticism, who do not like being told they are wrong, and do not like being told they are disseminating ignorance,” he told me on Monday. “Some of these people have shown themselves to be vindictive.” At the same time, he said, he felt that he could not remain silent. “There is no point in being a scientist if you are unwilling to defend the technical work you do, especially when that work is mischaracterized by powerful members of the Administration,” he explained.

Santer’s research in the early nineties was some of the earliest to demonstrate humanity’s influence on the global climate, and he has since added substantially to that body of work. While he has faced public and governmental pushback to his and his colleagues’ findings many times before, the experience of the past year and a half has been unprecedented, he said. He pointed to Pruitt’s Senate confirmation hearings, in January, 2017, in which the E.P.A. nominee claimed that satellite data shows a “levelling off of warming over the past two decades.” By examining all the satellite data “available in the world,” Santer said, he and several colleagues “were able to show that this claim was incorrect.” They published the results of their investigation in Nature Scientific Reports last May.

As Santer was preparing to publish that paper, two of his collaborators asked that their names be omitted from the finished manuscript, citing concerns that it would hamper their ability to obtain a green card. “I had never encountered anything like that, where my colleagues were afraid that their involvement in a peer-reviewed scientific paper could have very negative consequences for them, their families, their ability to remain in the United States,” Santer said. “I wish I could say, ‘These fears are irrational, you have nothing to worry about,’ but I could not do that. It seems we live at a time where ideology and adherence to ideology are more important than anything else.”

In 2016, three hundred and seventy-five scientists—many of whom signed Monday’s statement—published an open letter responding to Trump’s climate-denial campaign and warning against the dangers of a U.S. withdrawal from the Paris climate accord. Since then, the new statement points out, the suffering and economic loss wrought by “human-caused climate disruption” has only become “more obvious.” Among the references that Santer provided to N.A.S. members before they agreed to sign the statement were studies from the past year and a half showing that climate change notably increased Hurricane Harvey’s deadly flooding, was directly linked to severe coastal floods in New York City, was already responsible for hundreds of billions of dollars in economic losses in the United States, and had accelerated sea-level rise.

The statement also takes issue with the White House’s censorship of phrases such as “climate change,” “sea-level-rise,” and “science-based” in government reports and public communications, as well as a lack of expert scientific guidance within the Administration. “I would say there isn’t even any pretense at appointing qualified individuals to key scientific positions, which is deeply disturbing,” Santer said. “What if our nation faces another Deepwater Horizon? Where is the scientific expertise going to come from to provide guidance in difficult times? Those sorts of challenges will inevitably come.” He added that there is no Presidential science adviser, and that the Office of Science, Technology, and Policy “has been virtually gutted.” A request for comment from the White House went unanswered.

The N.A.S. is distinct from all other scientific societies in the country in that, although it is not a federal agency, it was set up by President Lincoln during the Civil War with the express purpose of providing scientific advice to the government. Its headquarters sit on the Washington Mall, across from the Vietnam Memorial, less than a mile from the White House. “We’d have to be incredibly naïve to think anything in the short run would impact the Trump Administration,” Manski told me. Still, he said, it is “very important” that prominent N.A.S. scientists have taken a public stand, in part because it may stir Congress to action. He noted that many social scientists are particularly concerned about the Census Bureau, which is severely underfunded and understaffed at precisely the moment when it should be gearing up for 2020.

Santer is ready for whatever consequences he may face as a result of the statement. “Frankly, there are far worse things to lose than your job,” he said. But he admits that it’s easy for him to say that; he’s nearing the end of his scientific career, and has been able to do most of the work that interests him. He also has grown accustomed to attacks from climate denialists. Since 1995, when he wrote a chapter in the Intergovernmental Panel on Climate Change report noting a “discernible human influence” on global warming, he has received threatening letters and calls. In 2009, he was one of the targets of Climategate, in which an unknown hacker published thousands of messages between climate scientists about complexities in the analysis of historical data. One night several years ago, Santer heard a knock on his door. When he opened it, he was greeted by a man yelling curses from the driver’s seat of a yellow Hummer. On the stoop lay a dead rat. He’s been on the lookout for yellow Hummers ever since.

“At its most basic level, the responsibility of government is to keep us safe from harm, to protect us,” he told me. “The government is failing in that responsibility.”

This article has been updated to include the statement's third author, Ray Weymann.