The Obama administration is downplaying hopes for reaching a global climate change treaty at the world summit in Copenhagen next month. On Wednesday, State Department climate change envoy Todd Stern said nations are unlikely to reach a deal in Copenhagen and should aim for an agreement in the following months. UN Secretary-General Ban Ki-moon has warned against delaying a climate treaty, citing the urgent need to begin cutting greenhouse gas emissions to avoid environmental catastrophe. Climate negotiators are currently meeting in Spain in advance of the Copenhagen talks. On Tuesday, delegates from the African bloc walked out of the negotiations, saying their concerns have gone ignored. The African countries said they would refuse to participate until richer nations agreed to consider making larger emissions cuts.