After a unanimous vote by the California Air Resources Board, the state adopted the most comprehensive cap-and-trade system in the country, a key part of a 2006 global warming law that had yet to be implemented. The system will cover 85 percent of greenhouse gas emissions in the state, and allows businesses to counterbalance up to 8 percent of their emissions by buying offset credits.

The state is making itself a guinea pig for climate legislation and hopes to inspire other states to follow suit—a precedent the state has set with other environmental legislation.