Leaders from across the world met this week at the United Nations in New York to dis- cuss how to combat climate change. Europeans rightly queued up to criticise the US for refusing to cap emissions of greenhouse gases. If the US, with its financial and technological resources, cannot decouple emissions growth from economic growth, there is little chance of persuading the developing world to curb its emissions.

The European Union is justified in claiming leadership on environmental policy. In March, European leaders agreed to cut EU emissions of carbon dioxide by 20 per cent by 2020, rising to 30 per cent if other countries step up to the challenge. This is great news as far as it goes. But setting emissions targets is all very well; the hard part is putting policies in place to meet them. In the EU's case, there is also the tricky issue of distributing the EU's overall emissions target among its member states.