I sometimes ask myself whether, in 20 years’ time, I will look back on everything I am writing at the moment and wonder why I wasted so much time on relative trivialities such as the Iraq war or the future of the Bush administration. Will such issues seem like footnotes in history, compared with the consequences of global warming?

A similar question of priorities has obviously occurred to Tony Blair. In the run-up to the most recent European Union summit, he and Jan Peter Balkenende, the Dutch prime minister, sent a joint letter about climate change to the other 23 EU leaders. “We have a window of only 10-15 years to take the steps we need to avoid crossing catastrophic tipping points,” they warned.