Hank Paulson, US Treasury secretary, warned on Thursday that the world would face “very, very bad outcomes” in the coming decades if nothing was done to reduce carbon emissions.

“There’s a huge scientific predicate that if we don’t do things today, we’re not going to be able to avoid the possibility of some very, very bad outcomes 30 or 40 years from now,” Mr Paulson told an audience at the Clinton ­Global Initiative, where he was introduced as an “ardent conservationist” by journalist Tom Brokaw.