Obama faces US government fight over carbon emissions
President Obama, speaking at the COP21 summit in Paris, has described climate change as a "generational problem". He insisted the world could forge a major agreement at the talks.
But in Washington, the Republican-led House of Representatives has directly challenged the president's environmental policies, organising votes that would abolish rules on reducing carbon emissions from power plants.
The BBC's North America Editor Jon Sopel has more on the growing debate in the US. Read
Produced by Ashley Semler; filmed and edited by John Landy