The United States on Wednesday officially became the only country in the world refusing to participate in global climate efforts, with the fate of the crisis hanging on the still uncalled presidential election.

Donald Trump as of Wednesday has withdrawn the US from the Paris climate agreement, an international pact to try to avert dangerous temperature increases that are already leading to more extreme weather and threaten to shrink world food supplies, force millions to flee their homes and deprive many of basic human rights. Trump’s administration set the US exit in motion a year ago, but it didn’t automatically take effect until 4 November.

The deal was meant to keep temperatures from rising more than 1.5C to