BEIJING (AP) — A groundbreaking agreement struck by the United States and China is putting the world's two worst polluters on a faster track to curbing heat-trapping gases blamed for global warming.

With the clock ticking on a worldwide climate treaty, the two countries are seeking to put their history as environmental adversaries behind them in hopes other nations will be spurred to take equally aggressive action.

The U.S. is setting an ambitious goal to cut greenhouse gas emissions. China is agreeing for the first time to a deadline for when its emissions will top out.

The dual announcements unveiled Wednesday in Beijing shocked environmentalists who feared China's reluctance and Obama's weakened political standing might make it impossible. Republicans were equally surprised and accused Obama of dumping an unrealistic obligation on his successor.