In this letter to The Wall Street Journal, Amory Lovins provides a public rebuttal to the prevalent perception that preventing climate change is too expensive to warrant the effort. Lovins argues that inaccurate computer models have created incorrect estimates for the high cost of climate protection. He explains the failure of this logic and the danger of the public and political misperception it has created. Sweden’s progressive energy policy is referenced as a guiding case study for global action.