President Donald Trump has announced that the US is withdrawing from the 2015 Paris climate agreement, the BBC reports.
He said moves to negotiate a new deal that would not disadvantage the US would begin.
Mr Trump said during last year’s presidential election campaign that he would take the step to help his country’s oil and coal industries.
The Paris agreement commits the US and 187 other countries to keeping global temperatures “well below” the level of 2C above pre-industrial times and “endeavour to limit” them even more, to 1.5C.
Earlier, UN Secretary General Antonio Guterres again appealed to Mr Trump not to break the commitment – but said the battle against climate change would continue regardless of the US stance.
Meanwhile, Chinese and EU leaders are set to agree a joint statement backing the Paris agreement, saying it is “an imperative more important than ever”.