Plans for an emergency summit of world leaders to break the international impasse on cutting greenhouse gases are being discussed by Ban Ki-moon, United Nations secretary-general. At the summit, mooted for September, heads of state would discuss the possibility of a successor to the Kyoto protocol on climate change, the main provisions of which expire in 2012. Mr Ban will fly to Nairobi on Tuesday to discuss plans for the summit, which are at an early stage, with officials from the UN Environment Programme, the body charged with tackling climate change. It would be among the first important commitments made by Mr Ban since he replaced Kofi Annan on January 1. He has chosen to stake some political capital on climate change, surprising US president George W. Bush by raising it at their meeting two weeks ago. Calling a summit would be a high-risk strategy. Heads of state may refuse the invitation, or fail to reach agreement, and Mr Ban will want to be sure of a full attendance before committing. Mr Bush is the leader most likely to decline, but any important agreement would be difficult without the US, the biggest emitter of greenhouse […]