For more than twenty years, climate change has divided citizens around the world. The conflicting sides have formed broad networks. They have advanced their goals in local, national, and international institutions. They have sought to convince the public and policy makers of their contrary views. At the same time, the factions have spared no effort to attack their foes – for methodological errors, scientific misconduct, and worse. Apparent milestones, like the Kyoto Protocol or the Copenhagen Summit, have in fact been mere way stations in an ongoing war. Basic matters – from the degree of warming, to its causes, to possible remedies, to their effects – remain contested.

This protracted battle over a matter portrayed as vital to the world's survival – or the economy's prosperity – is hardly unique. In issue after issue within countries and internationally, similarly discordant stories could be told. The death penalty, poverty alleviation, nuclear power, humanitarian intervention – these and countless others involve zealous activists persistently jousting over current decisions, future policies, and past interpretations.