President Donald Trump on his first day in office again withdrew the U.S. from a landmark global pact to fight climate change. So what is the Paris Agreement? And what happens to it now?

The United States will be one of only four countries outside the Paris Agreement, which is designed to reduce global greenhouse gas emissions.

President Donald Trump said Monday he will again withdraw the United States from the landmark Paris climate agreement, dealing a blow to worldwide efforts to combat global warming and once again distancing the U.S. from its closest allies.