Bending the threatening trajectory of global climate change surely seems daunting. Max Auffhammer argues that a single powerful tool can generate major change worldwide: price incentives. His focus is the social cost of carbon -- an estimate, expressed in dollars and cents, of the damage that one ton of CO2 emitted into the atmosphere has on the entire globe. This is a number that governments should use to evaluate the benefits and costs of new regulations that affect greenhouse gas emissions. (#33073)