President Trump has decided to withdraw from the landmark Paris Climate Agreement signed by President Obama in 2015, two people familiar with the decision told Axios. EPA Administrator Scott Pruitt is reportedly hammering out the details. “They’re deciding on whether to initiate a full, formal withdrawal — which could take three years — or exit the underlying United Nations Treaty, which would be faster but more extreme,” Axios reports. Trump tweeted Wednesday morning that a decision will be reached in “the next few days.” The agreement, dealing with greenhouse gas emissions, has been signed by every nation except Nicaragua and Syria. Climate scientists have expressed alarm at America’s decision: “If Trump … pulls out of the Paris Treaty, it is difficult to see a path forward to keeping warming below dangerous levels,” said scientist Michael Mann.