Lack of advancement in federal policy is being compensated for at the state level where many states are enacting ambitious climate change legislation. Number one among them is California, which, with its enactment of AB 32 (the Global Warming Solutions Act of 2006), has become the U.S. state leader in climate change action. AB 32 calls for economy-wide reductions of greenhouse gas emissions to 1990 levels by 2020 using a mandatory statewide cap on emissions beginning in 2012. In addition, an executive order by the Governor sets state targets seeking to reduce greenhouse gas emissions to 80% below 1990 levels by 2050. California has also initiated a partnership with the United Kingdom to collaborate on climate change research, technology, and best practices, and is working to link its carbon trading system to the Northeast’s Regional Greenhouse Gas Initiative trading system.

Other states have since followed suit, with Oregon, New Jersey, and Hawaii passing legislation in the summer of 2007 that impose mandatory caps on state emissions. Florida has made great strides recently as well, with Governor Crist signing three executive orders in July of 2007 that set emissions reduction targets for the state. In 2005, a group of Northeast and Mid-Atlantic states came together and agreed to form the Regional Greenhouse Gas Initiative. RGGI creates a carbon dioxide cap-and-trade program to regulate power plant emissions among the participating states.

In 2002, California enacted legislation authored by Assembly Member Fran Pavley regulating tailpipe emissions from vehicles that contribute to global warming. By 2004 the California Air Resources Board had approved regulations limiting the amount of greenhouse gasses that can be emitted by new vehicles starting with the 2009 model year. However, lawsuits from the automotive industry have hampered enforcement, and the state is currently awaiting a decision from the EPA on whether or not they will grant a waiver to allow California to put the regulation into effect. Should the waiver request be granted, twelve other states have adopted similar laws and will begin regulating greenhouse gas emissions from vehicles.

Renewable Electricity Standards have recently become a primary method for many states to take action on reducing greenhouse gas emissions. As of June 2007, 23 states and the District of Columbia have passed a RES, which mandates that a specific percentage of electricity used in the state come from renewable sources such as wind or solar power.