Yes, this really did just happen. From the NYTimes:
WASHINGTON — President Trump announced Thursday that he will withdraw the United States from participation in the Paris climate accord, weakening global efforts to combat climate change and siding with conservatives who argued that the landmark 2015 agreement was harming the economy.
But he will stick to the withdrawal process laid out in the Paris agreement, which President Barack Obama joined and most of the world has already ratified. That could take nearly four years to complete, meaning a final decision would be up to the American voters in the next presidential election.
Still, Mr. Trump’s decision is a remarkable rebuke to fellow heads-of-state, climate activists, corporate executives and members of the president’s own staff, all of whom failed this week to change Mr. Trump’s mind with an intense, last-minute lobbying blitz.
Earlier, Mike Pence prefaced Trump's announcement by saying the the president is "choosing to put American jobs and American consumers first," because of course the right to buy cheap lawnmowers and big SUVs is infinitely more important than the health of the planet we live on.
Trump's reasoning was predictably based on the Republican mythology that business and capitalism must be left alone in order for Americans to prosper (read rich white people), and the president declared the Paris Agreement to be a monumental job killer. Of course the complete opposite is true. For a great breakdown of why Trump's rationale is based on a pack of complete lies, read Greg Sargent's breakdown in the Washington Post, but the mere fact that every other major industrialized nation on earth is part of the agreement should say it all. America's abandonment of humanity's biggest efforts to save the planet is an abdication of leadership so extreme that the impact on America's political standing and future economic wellbeing is likely to be devastating. China and Europe are not going to take this sitting down, and America will find itself isolated like never before.
This isn't over, not by a long shot. While Trump and his genocidal cabal of nationalist bigots attempt to lay waste to their country and the planet, a resistance is mounting, and mounting rapidly. As Obi Wan Kenobi told Darth Vader before he killed him -- "You can't win Darth. If you strike me down, I will become more powerful than you can ever imagine".