Scott Pruitt, who resigned as Environmental Protection Agency administrator. (Jahi Chikwendiu/The Washington Post)

IT IS about time. It took months of revelation after damning revelation for President Trump to finally remove Scott Pruitt from the top job at the Environmental Protection Agency. Mr. Pruitt joins the ranks of former Trump administration officials forced to resign in disgrace, raising questions about why Mr. Trump hired them in the first place. At this point, a decent president would ask himself what he has been doing wrong.

The explanation for Mr. Pruitt’s curious longevity in office, seemingly impervious to widespread media coverage of his ethical lapses, could be seen in an over-the-top resignation letter in which he described Mr. Trump’s presidency as nothing short of “God’s providence.” His obsequiousness helped keep him in Mr. Trump’s good graces, and his continued fawning is likely calculated to maintain his appeal to pro-Trump GOP voters. This says nothing good about Mr. Pruitt, who combines ravenous ambition with a faulty moral compass, or about the president, who still appears to value loyalty, whether based in sincerity or cynicism, over the public good.

Mr. Pruitt blamed his departure on “unrelenting attacks on me personally.” Yet the remarkable thing about Mr. Pruitt’s story is his relentless petty corruption. In less than two years in Mr. Trump’s Cabinet, he took a generous rental deal on a condo owned by a major lobbyist’s wife, enlisted government employees to do menial personal tasks for him, obtained expensive 24-hour security, pressed to fly first-class and by private jet, saw extravagant office upgrades, used his position to try to get his wife a lucrative job and took extremely expensive foreign trips only glancingly related to his public responsibilities. Some staffers who objected to Mr. Pruitt’s waste were punished.

Now EPA Deputy Administrator Andrew Wheeler will fill in while the president finds a new leader for the agency. Mr. Wheeler is a longtime Washington insider unlikely to commit ethical mistakes on Mr. Pruitt’s scale. But anyone hoping for a broader change in direction at the EPA will have to keep waiting. Though Mr. Wheeler previously served on the EPA’s professional staff, he spent years working for Sen. James M. Inhofe (R-Okla.), an arch-climate denier, and as a coal lobbyist. His most prominent former client, coal magnate Robert E. Murray, is an aggressive opponent of important air-pollution rules that the Obama EPA tried to impose and that Mr. Pruitt began the process of ripping up. There is little doubt Mr. Wheeler will try to finish the job.

The New York Times reported Thursday that the EPA is poised to propose a comprehensive rollback of regulations that would require large cuts in greenhouse-gas emissions from existing power plants, a huge source of planet-warming emissions. In place of rules that would have mandated that the electricity system as a whole become steadily cleaner, the EPA would only call for small changes at individual power plants. Along with other regulatory changes on their way or already complete, this would represent a near-surrender on the part of the federal government on the issue of climate change.

Mr. Trump appears more concerned about what Fox News will say about his presidency in the next hour than what the history books will say in years to come. But if he cares about his legacy, he should choose a new EPA administrator who will address the urgent climate and other environmental issues the country faces.