Agence France-Presse: UN chief Ban Ki-moon on Sunday made an impassioned plea for a “cleaner, greener” world economy as he urged business leaders meeting in Copenhagen to back a new, global warming pact. “Today, I want to challenge you. I want to see you in the vanguard of an unprecedented effort to retool the global economy into one that is cleaner, greener and more sustainable,” the UN secretary general said in opening remarks to hundreds of business leaders in the Danish capital. “With your …