Agence France-Presse: Mayor Boris Johnson outlined plans to make London “the cleanest, greenest city on earth” by the 2012 Olympics and called for commitments from other world cities at a climate change conference. Leaders of the world’s 40 largest cities, plus 17 affiliate municipalities, are meeting in Seoul this week for a summit on combating global warming — the third to be held since 2005. “What we should do in Seoul is agree that we will stop the endless addiction of mankind to the internal …