After months of hinting, President Donald Trump finally announced his intention to pull the United States out of a global agreement to curb greenhouse gas emissions on Thursday. He said that he would work toward negotiating a new climate deal that would be "more fair" to American workers instead, even though the original Paris Agreement was voluntary.

Trump's decision could severely undermine the pace of climate progress, discouraging other countries from meeting their own commitments, limiting the U.S.'s ability to steer discussion, and ceding jobs and the economic windfall of an ongoing energy revolution to countries such as China.

But 18 months after more than 190 countries agreed in Paris to take steps to avoid a two-degree Celsius rise in