..This is fast becoming Obama's role on the world stage: managing disappointment. The gap between what international opinion demands of him and what he can deliver widens with each passing month, and it falls to him to explain why. If he could be completely frank, he might well tell the climate activists in the Danish capital that, were it purely up to him, he would give them everything they desire. After all, he is the same man whose stump speech two years ago used to open with a declaration that "the planet is in peril". But it is not purely up to him. He has to represent the multiple, complex and contradictory interests of the country he now leads. His job is not saviour of the world. As the climate adviser to a 19-strong group of African nations puts it ruefully: "He's still an American president."