Scientists from 13 federal agencies have written a climate report that contradicts president Donald Trump’s assertions that global warming may be natural. The draft report, first published by the New York Times, says that "many lines of evidence demonstrate that human activities ... are primarily responsible for recent observed climate change." It adds that the U.S. has experienced "rapid warming since the late 1970s, while paleo-temperature evidence shows that recent decades have been the warmest in at least the past 1,500 years." In an accopmanying article, the Times explains that one scientist who helped put together the report says that he and some of the other researchers behind it fear that the document may be supressed by the current administration.

That concern is in fact shared by many scientists involved in the report, which is component of the congressionally mandated National Climate Assessment. Donald Wuebbles, a climate scientist at the University of Illinois at Urbana-Champaign and co-chair of the report, told Nature, “We can’t allow science to be held hostage...I’m hopeful it won’t get to that, because it would look really bad for the administration to fight this.”

If the Trump administration does stand in the way of the report, it could face more than just bad optics. The National Climate Assessment must be released every four years—in 2004, environmental groups sued the George W. Bush administration in federal court for missing its deadline, and successfully forced the administration to release the assessment.