The White House repeatedly attempted to thwart the country’s premier climate science document, one meant to steer policy for years. Scientists got in the way.

The National Climate Assessment, America’s premier contribution to climate knowledge, stands out for many reasons: Hundreds of scientists across the federal government and academia join forces to compile the best insights available on climate change. The results, released just twice a decade or so, shape years of government decisions.

Now, as the clock runs down on President Trump’s time in office, the climate assessment has gained a new distinction: It is one of the few major U.S. climate initiatives that his administration tried, yet largely failed, to undermine.

How the Trump White House attempted to put its mark on the report, and why those efforts stumbled, demonstrates the resilience of federal climate science despite the administration’s haphazard efforts to impede it. This article is based on interviews with nearly a dozen current and former government officials and others familiar with the process.

In November, the administration removed the person responsible for the next edition of the report and replaced him with someone who has downplayed climate science, though at this point it seems to be too little, too late. But the efforts started back in 2018, when officials pushed out a top official and leaned on scientists to soften their conclusions — the scientists refused — and then later tried to bury the report, which didn’t work either.

“Thank God they didn’t know how to run a government,” said Thomas Armstrong, who during the Obama administration led the U.S. Global Change Research Program, which produces the assessment. “It could have been a lot worse.”

What makes the failure to impede the climate assessment remarkable is that Mr. Trump has made it a top priority to undercut efforts to address climate change. And on most fronts, he succeeded, reversing scores of environmental rules, relaxing restrictions on air pollution and opening new land to oil and gas drilling.

The national assessment enjoys unique prominence, pulling together the work of scientists across the federal government. The law requires a new one every four years.

For Mr. Trump, who has called climate change a hoax, the assessment posed a particular challenge. Trying to politicize or dismiss climate science is one thing when the warnings come from Democrats or academics. But this report comes from his administration’s very own agencies.