https://www.scientificamerican.com/article/u-n-climate-talks-limp-to-a-disappointing-close/

MADRID—More than two weeks of U.N. climate talks ended yesterday with little headway on a key issue related to the Paris climate accord—an impasse that frustrated both activists and negotiators, and one that raised fresh worries about the future of the planet.

The breakdown occurred even after negotiators worked more than 40 hours past the official close of the talks to try to reach a resolution. But the long hours and sleepless nights didn’t yield agreement on the last piece of the Paris Agreement’s rulebook: guidelines for how international carbon markets would serve the 2015 climate deal.