The US has unexpectedly joined a large group of countries trying to isolate China and India in the tense home stretch of UN talks in Paris on a new global climate agreement. The group, which has dubbed itself the “high ambition coalition”, claims to include about half the 195 nations involved in the two-week Paris meeting known as COP21, which is due to end on Friday. “This is our moment and we need to make it count,” said Todd Stern, the US climate envoy, as he joined ministers from the EU, Latin America, Africa and Pacific islands at a news conference on Wednesday evening to demand that the new accord contain measures that China, India, Saudi Arabia and other nations are trying to resist. That includes an acknowledgment that global temperatures should not rise more than 1.5C from pre-industrial times and provisions to ensure this goal is met by requiring countries to update their emissions reduction pledges every five years, starting as soon as possible.