WASHINGTON - On Dec. 5, 2007, EPA Administrator Stephen L. Johnson prepared to send the White House an extraordinary document. It declared that climate change imperiled the public welfare - a decision that would trigger the nation's first mandatory global-warming regulations.

Johnson, a career scientist, knew that his draft would meet with resistance from antiregulatory ideologues at the White House, but he believed the science was solid.

According to confidential records reviewed by The Inquirer, Johnson cited strong evidence: rises in sea level, extreme hot and cold days, ecosystem changes, melting glaciers, and more. Minor doubts about long-term effects, he wrote, were not enough to alter his conclusion.

Two sentences in Johnson's draft stood out. In sum: The U.S. emits more greenhouse gases from cars than most countries do from all pollution sources. This fact is so compelling that it alone supports The Administrator's finding.

At 2:10 p.m., Associate Deputy Administrator Jason Burnett e-mailed the climate-change draft to the White House as an attachment.

What happened next became Johnson's defining moment and cemented President Bush's environmental legacy, serving as the low-water mark of a tumultuous era that has left the EPA badly wounded, largely demoralized and, in many ways, emasculated.

White House aides - who had long resisted mandatory regulations as a way to address climate change - knew the gist of what Johnson's finding would be, Burnett said. They also knew that once they opened the attachment, it would become a public record, making it too controversial to rescind. So they didn't open it.

They called Johnson and asked him to take it back.

The law clearly stated that the final decision was the EPA administrator's, not Bush's. Johnson initially resisted - something Burnett admired - but ultimately did as he was told.

Outraged, Burnett resigned.

In July, Johnson issued a new, censored version, a pale imitation of the original climate-change document.

The old muscular language - including key sentences about U.S. car emissions and the irrelevance of any lingering doubt - was gone. Most of all, the new document no longer declared global warming a danger to public welfare. The move effectively postponed any strong action on climate change well into the next administration.

This was by no means the only example of how Johnson and an antiregulatory Bush administration weakened the federal agency charged with safeguarding human health and the environment. But what happened on climate change dwarfed everything else.

"The country and the environment have been on hold for eight years," said William K. Reilly, who led the EPA under President George H.W. Bush. "The scorecard is very, very disappointing. For a long time, conservatives have said follow the science, and in the climate-change decision, [EPA] did not follow the science - it abdicated leadership and responsibility."

Johnson, whose image over four years morphed from scientist to ideologue, will leave office as one of Bush's most loyal and controversial cabinet members. His decisions alarmed environmentalists, infuriated his own scientists, and led to calls from Democrats for his resignation.

Critics include Reilly and three other Republicans who have held the top EPA post. In interviews, they said Johnson should have exercised his legal authority to stand up to Bush on climate change.

"Here we see a real failure of leadership," said Russell Train, EPA administrator during the Nixon and Ford eras. "EPA has become a nonentity."

Johnson, a savvy Washington native who grew up discussing politics at the breakfast table, said the former administrators should know that EPA chiefs can rarely please everyone.

"There's always those who say you haven't gone far enough, and others who say you've gone too far," he said. "I won't accept the criticism that I didn't care about or didn't do anything to advance the environment."

Bush's chief White House adviser on the environment, James L. Connaughton, said the president believes Johnson has been an excellent EPA chief.