Al Gore has been busy returning global warming to centre stage with terrifying warnings of disaster with his bestselling book, An Inconvenient Truth, and the popular companion documentary. Tony Blair, the UK prime minister, has joined – even led – the renewed focus on global warming, charging Sir Nicholas Stern, the economist, with solving the problem. Alongside his successful initiative on Africa, this is to be his sure-fire international legacy as he ends his last term in office.

Getting global warming on the radar screen is only half the game, however. The other half has to be the design of policies to address it effectively. The centrepiece of world action has been the 1997 Kyoto Protocol to the Framework Convention on Climate Change. But while it embodied national obligations on carbon dioxide emission reductions and has now been ratified and approved by more than 160 countries, the US has not done so. So, the Kyoto protocol is dead in the water: you cannot stage Hamlet without the Prince.