Green Thoughts: 1. Cap and Trade: An Unserious Policy Framework for Humanity’s Most Serious Challenge In a few days in Copenhagen, world leaders will debate and, we hope, agree upon aggressive targets for humanity’s greatest challenge to date: to avert devastating man-made climate change by transforming our economies’ use of energy and of land while maintaining and improving social welfare for the world’s peoples. We have in the past 250 years proceeded on a course of development which has used …