The Paris agreement is a mostly voluntary climate pact originally written to both try to reduce warming and withstand the changing political winds in the U.S.

The United States’ second exit from the Paris Agreement wasn’t unexpected. Even before he was reelected, now-president Donald Trump had promised for months that he would pull the country out of the United Nations pact to limit global warming: the Paris climate “ rip-off ,” as he called it.

Trump said the US would withdraw from the Paris climate accord for a second time, a defiant rejection of global efforts to combat planetary warming.