On September 27, 2006 Schwarzenegger signed a bill creating the nation's first cap on greenhouse gas emissions. The law set new regulations on the amount of emissions utilities, refineries and manufacturing plants are allowed to release into the atmosphere. Schwarzenegger also signed a second global warming bill that prohibits large utilities and corporations in California from making long-term contracts with suppliers who do not meet the state's greenhouse gas emission standards. The two bills are part of a plan to reduce California's emissions by 25 percent to 1990s levels by 2020. In 2005, Schwarzenegger issued an executive order calling to reduce greenhouse gases to 80 percent below 1990 levels by 2050.

What date marked the first law restricting greenhouse gas emissions?