COPENHAGEN — Climate-change heavyweights U.N. chief Ban Ki-moon and Nobel prize winner Al Gore urged more than 500 business leaders on Sunday to lend their corporate muscle to reaching a global deal on reducing greenhouse gases. The CEOs of PepsiCo, Nestle, BP and other major world businesses began meeting in Copenhagen, where politicians will gather in December to negotiate a new U.N.-brokered climate treaty. Despite the global financial crisis, both Ban and Gore said there was no time for delay in hashing out the specifics of how to cut greenhouse gases that contribute to warming the planet. "We have to do it this year.