President Joe Biden told world leaders Thursday that the Trump era of climate denialism is over—and that the United States is now committed to slashing its planet-warming emissions in half by the end of the decade. Biden made the announcement Thursday morning to kick off a virtual two-day summit on climate change that is also being attended by Russian President Vladimir Putin and Chinese President Xi Jinping. Biden confirmed that his new target will seek to have U.S. greenhouse-gas emissions drop 50 to 52 percent below 2005 levels by the end of 2030. A White House official who briefed reporters ahead of the announcement said the target will “unmistakably communicate that the United States is back” after ex-President Donald Trump’s reckless denial of the climate crisis. “The United States isn’t going to wait, the costs of delay are too great and our nation is resolved to act right now,” the official said.