But it’s looking increasingly likely that the next big international agreement on climate change will not be a legally binding treaty like the 1997 Kyoto Protocol, which required developed countries to reduce greenhouse gases by specific amounts (and which was rejected by the United States and, more recently, Canada).

Nor will the next global climate deal likely require the deep reductions in greenhouse gas emissions that scientists say would be necessary to prevent catastrophic impacts from global warming, according to current and former Obama administration officials and other observers of ongoing international climate negotiations.

There are lots of reasons why a treaty is unlikely, beginning with the near certainty that the U.S. Senate would not ratify one. The United States is the