President Trump was poised Wednesday to withdraw the United States from the Paris climate agreement, two officials with knowledge of the decision said, making good on a campaign pledge but severely weakening the landmark 2015 climate change accord that committed nearly every nation to take action to curb the warming of the planet. But White House officials cautioned that the decision is not yet final. Faced with advisers who pressed hard on both sides of the Paris question, Mr. Trump appears to have decided that a continued United States presence in the accord would harm the economy; hinder job creation in regions like Appalachia and the West, where his most ardent supporters live; and undermine his “America First” message. But advisers pressing him to remain in the accord were still pressing up to the final announcement. and, from the atlantic The Paris Agreement on climate change works by a delicate bit of magic. The treaty aims to reduce the world’s greenhouse-gas emissions, but it legally requires no one to actually stop emitting greenhouse gases. Instead, it advances a set of loose and voluntary norms for getting to the final goal. In 2015, every country announced a (nonbinding) plan in which they promised to (eventually) slow down pumping carbon dioxide and methane into the atmosphere. In 2018, and every five years afterward, all the countries will get together again and announce new promises. This looseness was intentional. The accord’s architects hoped to nudge everyone into bringing down their emissions together—but they didn’t (and couldn’t) forceany one nation to do it. More pointedly, they also could not compel a Republican-controlled U.S. Senate to ratify any binding international climate treaty. So Paris trades in signals, not sacrifice; unanimous resolutions, not top-down restrictions. John Kerry said during negotiations that it sends “literally a critical message to the global marketplace.” In truth, this is pretty much the only thing it does.