Guardian: For a man with the very survival of human civilisation weighing heavily on his broad shoulders, Al Gore cuts a surprisingly relaxed figure. With a Diet Coke in hand, and chewing gum rolling around inside his mouth, one of the great “what ifs” of modern political history strolls into the boardroom of his London-based asset management firm, located in one of the city’s “most environmentally friendly buildings”. Gore is in the capital, as he is every few months, to spend a couple of days …