As time passes, those calling for aggressive government action in the name of fighting climate change have had to ramp up their rhetoric and, in many cases, change their story from just a few years earlier. A recent example is Paul Krugman, when he describes a new IMF study by saying that government policies to reduce carbon dioxide emissions may now have zero cost. (!) Not only is this totally wrong—the study’s authors certainly claim no such thing—but it contradicts what a more sensible Krugman wrote back in 2009, when he warned his green comrades to not say cringe-worthy things about there being free lunches in fighting climate change.