conference, the clean power plan hasn't gone into effect. more than two dozen states sued to stop it, the supreme court ordered the implementation delayed until the appeals play themselves out. and now president-elect trump has vowed to rescind it. but what will he do with obama's signature climate achievement -- the paris agreement? in december of 2015 in the city of light 196 nations agreed by consensus to limit the planet's warming to two degrees celsius. that's a threshold many scientists believe will prevent disaster. >> of course it took a long time to reach this day. one of the reasons i ran for this office was to make america a leader in this mission. >> and america is now undoubtedly a leader, perhaps the leader, on climate change.