Al Gore vented the frustration of many at Bali when he accused the US of blocking efforts to tackle global warming. Perhaps the former US vice-president spoke too soon. The deal struck on Saturday by about 190 nations will not on its own cut greenhouse gas emissions. But it is an important milestone.

America has not budged on the biggest issue. The world’s heaviest emitter of carbon dioxide refused to agree to European Union demands for targeted reductions in emissions of between 25 and 40 per cent by 2020. The omission of specific targets from the Bali plan was a regrettable shortcoming, but no reason to call it a failure.