text: FILE -- Emissions from the Kentucky Utilities coal-fired Ghent Generating Station in Ghent, Ky., June 2, 2014. The U.S. has emitted more planet-warming carbon dioxide into the atmosphere than any other country, and now, it may be walking back a promise to lower emissions if President Donald Trump decides to abandoned the 195-nation agreement on climate change reached in Paris in 2015. (Luke Sharrett/The New York Times