Guardian: US president Barack Obama has laid out his legacy on one of the issues that will define the world long after his brief term in power is over. He has been frustrated in several other attempts to bring climate change to the fore of US politics, with the demise of cap and trade plans a notable failure, but his move to use the Environmental Protection Agency to cap carbon emissions is his boldest effort yet, trying to circumvent the Congressional stalemate on the issue using his constitutional powers....