Agence France-Presse: For the past decade, the effort to muster an alliance of nations to fight climate change has seemed at times like a train wreck in slow motion. In Copenhagen last week, there were moments when that crash finally — horribly — appeared to have happened. The United Nations had billed December 18 2009 as the day when all countries would rally under its banner, forging a strategy to combat the greatest threat facing humanity this century. Instead, the day will be recalled …