In late 2006, President George W. Bush’s Environmental Protection Agency argued before the Supreme Court that it did not want to regulate greenhouse gases, and that no one could make it do so. It certainly had no wish to accede to the desires of Massachusetts, which, with eleven other states, had sued the E.P.A. for failing to establish guidelines on emissions of carbon dioxide, methane, nitrous oxide, and hydrofluorocarbons. The states pointed to the agency’s charter, under the Clean Air Act, which instructs it to regulate chemicals released into the air “which may reasonably be anticipated to endanger public health or welfare.” They asked why the E.P.A., which had refused even to consider whether greenhouse gases fell into that category, thought that it could ignore the law.

The Court, in a landmark 5–4 decision, written by Justice John Paul Stevens and issued ten years ago this week, agreed with the states. As a result of that ruling, the E.P.A. began the formal process of looking at the science documenting the risks posed by greenhouse gases, and recognized that those emissions had contributed to a public-safety crisis affecting not just the nation but the planet. The E.P.A.’s resulting “endangerment finding,” as it is known, was issued in 2009, in time for Barack Obama’s Presidency. It became the immediate object of conservative scorn and of furious efforts in Congress and the courts to invalidate it, but it held up, and formed the basis for new standards on auto emissions and for Obama’s Clean Power Plan, issued in 2015. More than that, the finding was an assertion of the principle that politicians cannot entirely ignore either science or the rule of law.

We now have, in Donald J. Trump, a President who shows disdain for both. Trump’s lack of interest in climate change as anything other than fodder for conspiracy theories involving Chinese hoaxers reached its fullest expression last week, in a “Presidential Executive Order on Promoting Energy Independence and Economic Growth.” The order asks every agency of the federal government to review its rules and to purge them of measures that inconvenience the fossil-fuel and nuclear-power industries. In particular, it directs the E.P.A. to rewrite the Clean Power Plan, which had called for, among other things, the replacement of old and dirty coal-burning plants. The plan would, it was projected, result in eight hundred and seventy million fewer tons of carbon pollution released into the atmosphere, as many as thirty-six hundred fewer premature deaths in the United States between now and 2030, and ninety thousand fewer asthma attacks in children.

President Trump said that his order puts “an end to the war on coal.” In reality, it is a declaration of war on the basic knowledge of the harm that burning coal, and other fossil fuels, can do. Indeed, it tells the government to ignore information. The Obama Administration assembled a working group to determine the “social cost” of each ton of greenhouse-gas emissions. Trump’s executive order disbands that group and tosses out its findings. Scott Pruitt, the new E.P.A. administrator—who, as attorney general of Oklahoma, had joined a lawsuit attempting to undo the endangerment finding—announced that the agency was no longer interested in even collecting data on the quantities of methane that oil and gas companies release.

The order also revokes several of President Obama’s executive orders and memorandums. One of them, “Preparing the United States for the Impact of Climate Change,” sought to remove regulations that deterred private industry from responding to climate change in innovative ways; another asked the military to assess the threats posed by climate-induced upheaval abroad—wars, famines, flows of refugees. Trump further called for a scrubbing of any reports or rules that might have developed in response to those documents, and thus any insights that might have been gleaned from them. He chooses to cast such worries aside at the Winter White House, Mar-a-Lago, even as that property sinks into the rising sea, a process that has begun and, by many scientific estimations, will result in its grounds becoming one with the Atlantic during Barron Trump’s lifetime.

For all the talk of American greatness, Trump’s actions regarding climate change represent a historic abdication of leadership. The Clean Power Plan was important not only for its domestic effects but because it was a down payment on America’s commitments under the Paris climate accords. If fully implemented, the plan would have got the United States about halfway to the goal of reducing greenhouse-gas emissions by a quarter, from their 2005 levels, by 2025. Without the plan, the goal will almost certainly not be reached, despite the pledges of several states and even some large energy concerns to adopt greener technology. Meanwhile, China, in a reversal, is proclaiming itself to be the champion of Paris, if only as a way of enhancing its own world-leader credentials.

Trump says that he is still deciding whether to formally withdraw from Paris, but it is now clear that if he doesn’t it will only be because he can’t be bothered with the paperwork. The United States government’s meaningful participation in the fight against climate change appears, at least for the next few years, to be at an end. The Friday before issuing the order, in what looked like an attempt to cheer up Republicans about their health-care defeat, Trump granted a permit for the completion of the Keystone XL Pipeline, which the Army Corps of Engineers had earlier blocked.

Much of this will end up in the courts, as yet another set of Trumpian actions that make the expected confirmation of Neil Gorsuch to the Supreme Court so consequential (and the abandonment of Merrick Garland so tragic). Gorsuch’s mother was a notably anti-environmentalist head of the E.P.A., under Ronald Reagan, and Gorsuch would take the seat formerly occupied by one of his judicial idols, Antonin Scalia, who was in the minority in Massachusetts v. E.P.A. (In his dissent, Scalia grumpily wondered why the agency couldn’t just say that climate-change science was unsettled, and leave it at that.) The Trump Administration has already proposed defunding the E.P.A. by thirty-one per cent and cutting its staff by twenty per cent, raising questions about how it can fulfill its most basic responsibilities. Soon enough, the Supreme Court may be asked, again, what it means for the E.P.A. to be derelict in its duties, and for America to have a President whose main mode of action is reckless endangerment. ♦