Agence France Presse: The top United Nations climate official called Thursday on rich nations to lead the fight against global warming, but said a breakthrough was unlikely at next week’s G8 summit in Japan. “At this moment it doesn’t look very encouraging,” said Yvo de Boer, Executive Secretary of the UN Framework Convention on Climate Change (UNFCCC). He told AFP that the G8 nations — France, Germany, Britain, Canada, Japan, Italy, Russia and the United States — would probably not be …