The Paris Agreement—which entered into force only on November 4—is already in jeopardy amid rumors that the U.S. might pull out. This could lead to a reduction in efforts by China and other nations. The Paris Agreement is really the first important step taken to limit temperature increase, and, as highlighted in the e-book “Towards a Workable and Effective Climate Regime,” by Scott Barrett, Carlo Carraro, and myself last year, it must meet two conditions that look increasingly difficult to attain. Meeting these conditions will be difficult for reasons related to science and to the U.S. election outcome.