This article is part of the Debatable newsletter. You can sign up here to receive it on Tuesdays and Thursdays. Six years ago in Paris, world leaders celebrated a breakthrough in global climate politics: After more than two decades of failure, nearly every country finally agreed to reduce “as soon as possible” the amount of planet-warming greenhouse gases they were pumping into the atmosphere. Those leaders knew, though, that their pledges were woefully insufficient to avert disaster and would need to be ratcheted up at a later date. That is…