Almost 200 countries have agreed to the terms of a new international deal to tackle climate change following United Nations talks in Paris.
Cheers and applause broke out as the agreement - which includes a pledge to keep temperature rises "well below" 2C - was officially passed.
Prime Minister David Cameron said the deal had "secured our planet for many, many generations to come."
The US president has welcomed the Paris climate change agreement, saying it demonstrated "what's possible when the world stands as one".
Barack Obama emphasised the US role in the developments that led up to the Paris agreement, including the US role in the earlier 2009 Copenhagen talks, but said the Paris agreement had only been achieved because nations came together.
"Today the American people can be proud because this historic agreement is a tribute to American leadership. Over the past seven years, we've transformed the United States into the global leader in fighting climate change," Obama said.
He said the agreement was not perfect, but that it "establishes the enduring framework" to solve the climate crisis.
George Osborne was warned he could be breaking law with cuts to investment in renewable and green energy
Prime Minister David Cameron has welcomed the final approval on an historic international deal to tackle climate change.
WWF-UK's chief executive, David Nussbaum, writes for ITV News after the release of the final draft of the Paris Agreement on climate change.