There are two market ways to reduce C02 emissions (the other options, like “command and control” would involve more overt government intervention). The first is cap and trade. The U.S. tried, and failed to pass a cap and trade bill in 2009 (Waxman-Markey). In a cap and trade system, the government puts a “cap” on the amount of carbon that can be emitted and allows companies to trade permits that allow them to emit, say a ton of CO2, on a market. The idea is that companies that can cheaply reduce emissions will do so, and then sell their permits to those who can’t do so cheaply.