Europe must make clear to the United States that quitting the Paris climate agreement is not a straightforward process, and that fully leaving the deal will take years, European Commission President Jean-Claude Juncker said on Wednesday. "The Americans can't just leave the climate protection agreement. Mr. Trump believes that because he doesn't know the details." In reality, it would take several years for the U.S. to extricate itself from the obligations that flow from having signed the agreement, the head of the European Union's executive arm added.