With the sudden bang of a gavel Saturday night, representatives of 195 nations reached a landmark accord that will, for the first time, commit nearly every country to lowering planet-warming greenhouse gas emissions to help stave off the most drastic effects of climate change.
The deal, which was met with an eruption of cheers and ovations from thousands of delegates gathered from around the world, represents a historic breakthrough on an issue that has foiled decades of international efforts to address climate change.
President Obama, who regards tackling climate change as a central element of his legacy, spoke of the deal in a televised address from the White House.
"This agreement sends a powerful signal that the world is fully committed to a low-carbon future," he said.