Agence France-Presse: The head of the European Commission warned on Thursday that European leaders must "rethink" their approach to climate change negotiations with major partners such as China and the United Sates. In a letter to the 27 European Union leaders, Jose Manuel Barroso said a UN summit in Copenhagen in December at which bloc negotiations were outmaneouvred "showed us just how tough it will be" to convince the world to adopt similar policies. "Copenhagen was a reality check," Barroso said …