Unmitigated climate change is extremely costly. Mitigation (the reduction of carbon dioxide and other greenhouse gas emissions at the source) is the only prudent response. While upfront costs can be high, in the long run mitigation is relatively cheap and because it tackles the root cause of the problem, its benefits are permanent and transparent. However, because the effects of mitigation investments are subject to considerable physical and social inertia, they are slow to manifest. Moreover, effective mitigation requires overcoming the well-known “free rider” effect inherent in the most global of global commons problems.