The frustration in Warsaw showed an ongoing failure among many staunch advocates of climate diplomacy to learn the key lesson of Kyoto: Legal force is the wrong litmus test for judging an international framework. Idealized multilateralism has become a trap. It only leads to countries agreeing to the lowest common denominator — or balking altogether.

Evidence shows that a drive for the tightest possible treaty obligations has the perverse effect of provoking resistance. In a seminal 2011 study of climate diplomacy, David Victor of the University of California, San Diego, concluded, “The very attributes that made targets and timetables so attractive to environmentalists — that they set clear, binding goals without much attention to cost — made the Kyoto treaty brittle because countries that discovered they could not honor their commitments had few options but to exit.”

This argument may sound like one made by many political conservatives, who opposed Kyoto and have long been wary of treaties in general. But the point is not that international efforts are useless. It is that global agreements are most useful when they include a healthy measure of realism in the demands that they make of countries. Instead of insisting on a binding agreement, diplomats must identify what governments and other actors, like the private sector, are willing to do to combat global warming and develop mechanisms to choreograph, incentivize, and monitor them as they do it. Otherwise, U.N. talks will remain a dialogue of the deaf, as the Earth keeps cooking.