China and US formally enter landmark climate deal

Co-operation is "the single best chance that we have" to save the planet, US president Barack Obama said, as he stood with China's president Xi Jinping to formally enter their two nations into last year's Paris climate change agreement.

At a ceremony on the sidelines of the G20 summit in Hangzhou, Obama and Xi, representing the world's two biggest carbon emitters, delivered documents to UN secretary-general Ban Ki-moon.