President Emmanuel Macron of France tried this week during President Trump’s visit to Paris to get him to reverse his decision to take America out of the landmark global agreement on climate change, struck in December 2015 and since ratified by 153 nations. It was a futile exercise, as he must have known it would be.

At one point, Mr. Trump seemed to leave the door open for some unspecified compromise. But nobody knows what that would be. And in any case it is likely to be meaningless, because there is zero chance that he would reaffirm President Barack Obama’s commitment to make meaningful reductions in America’s greenhouse gas emissions, or seek to re-establish the leadership role that Mr. Obama occupied and that Mr. Trump has now abdicated.

In short, despite Mr. Macron’s efforts, the gap between Mr. Trump and the rest of the world on climate remains as wide and unbridgeable as it was at the Group of 20 summit meeting the week before, when the final communiqué contained a robust commitment from 19 of the world’s leading economic powers to fight climate change and one pathetic little sentence in which the United States said it would “endeavor” to “use fossil fuels more cleanly and efficiently.” Mr. Trump had apparently hoped for some support from other big fossil fuel producers, like Russia and Saudi Arabia. This was not forthcoming, heartening those who feared (and still fear) that Mr. Trump’s betrayal of America’s commitments would cause other countries to backslide as well.

The unanswered question is whether the goals set in the Paris accord can be reached without United States participation. To recap briefly, the accord sought to limit the rise in atmospheric temperatures to 2 degrees Celsius above preindustrial levels and 1.5 degrees if possible. To that end, Mr. Obama pledged to reduce America’s greenhouse gases by 26 to 28 percent by 2025, largely through greater fuel efficiency for cars and light trucks, limits on methane emissions from oil and gas wells, and new rules governing emissions from new and old coal-fired power plants.