Guardian: With Hillary Clinton’s sudden appearance at the Copenhagen summit at its moment of crisis – and the prospect of billions in cash – America today lays claim to the role of lead broker in what could be the deal of the century. Clinton’s intervention, on a day that began with the Danish hosts of the talks saying they had given up hope of a deal, allows the US to claim a role in helping to unite countries that were turning on each other. "It is no secret that we have lost time," …