US and Chinese cities reveal stronger pledges to cut emissions

New, more ambitious goals from dozens of major cities boosts earlier historic deal between the world's two biggest carbon polluting countries

China's mega-cities and major US metropolitan areas will pledge swifter and deeper cuts in carbon pollution on Tuesday, shoring up an historic agreement between presidents Barack Obama and Xi Jinping.

Beijing and 10 other Chinese cities will agree to peak greenhouse gas emissions as early as 2020 - a decade ahead of the existing target for the world's biggest emitter, under a deal to be unveiled at a summit in Los Angeles on Tuesday.