Negotiators opened their first talks Monday on forging a global warming pact to succeed the Kyoto Protocol _ and faced wide divisions between rich and developing countries over how to slash greenhouse gases. The weeklong gathering of representatives from 163 countries launched a 21-month process aimed at concluding a new climate change agreement by December 2009 to rein in gases such as carbon dioxide blamed for the rise in world temperatures. Organizers of the U.N.-led talks _ mapped out in a massive conference in Bali in December _ urged delegates to work quickly to ensure action before the worst effects of global warming such as extreme weather become unavoidable. «With the 2009 deadline, we have just one and half years in which to complete negotiations on what will probably be the most complex international agreement that history has ever seen,» said Yvo de Boer, U.N. climate change executive secretary. «And I'm confident that it can be done.» Many scientists and the United Nations agree that the world needs to stabilize emissions of greenhouse gases in the next 10-15 years and slash them by 50 percent by 2050 to prevent temperatures from triggering devastating changes in the environment, the Associated Press reported.