When China and the United States agreed a year ago to scale back greenhouse gas emissions, they set the stage for this month's international climate talks in Paris. But Paris is not just about these two powerhouses, even though they account for one-third of fossil fuel emissions. Curbing the threat posed by climate change truly takes global action.

So far, more than 150 countries – from Sudan to Suriname and from Kiribati to Kyrgyzstan – have outlined for United Nations negotiators just how, when, and by how much each would cut carbon dioxide over the next several decades. If an agreement is reached during the talks that start Nov. 30, it would mark the first serious global commitment to reduce the