The Democratic governor was joined Tuesday by his celebrity predecessor, Arnold Schwarzenegger, who signed the 2006 bill that led to the creation of the nation's only cap and trade system to reduce greenhouse gases.
The program puts a cap and a price on climate-changing emissions. It has become closely watched around the world, promoted by Schwarzenegger and Brown alike as a successful way to reduce emissions that hasn't taken the steam out of California's thriving economy.
Brown's signature adds 10 years to the program, which had been scheduled to expire in 2020. It follows a frenetic push by Brown to craft a plan that businesses and environmentalists would both find acceptable.