Ahead of a major summit on global warming next month, UN climate talks have been slowed down as China and the US are locked in a stand-off. The six days of talks in the northern Chinese city of Tianjin saw the major powers sparred throughout, prompting the hosts to warn on the penultimate day that the atmosphere for negotiation had deteriorated. Delegates from more than 170 countries attended the latest round of the long-running UN negotiations that are aimed at eventually securing a binding global treaty on how to limit and cope with climate change. The Tianjin meeting was the last big gathering before an annual UN climate summit, which will be held in Cancun, Mexico, from November 29 to December 10.