BALI, Indonesia - World powers meeting at a UN climate change conference in Indonesia this week won't be able to craft a meaningful plan to address global warming without co-operation from the United States, the top emitter of greenhouse gases, the UN's climate chief said Sunday. The United States refused to sign the last major international treaty on reducing greenhouse gases, undermining its effectiveness. Delegates from 190 countries will gather on the resort island of Bali on Monday for one of the largest global warming conferences ever, bringing together about 10,000 people including Hollywood luminaries, former vice-president Al Gore, fishermen...