SACRAMENTO, Calif. -- Gov. Arnold Schwarzenegger signed an executive order Thursday that will make California the first place in the world to require low-carbon gasoline.

Environmentalists and oil executives joined the governor for the signing.

The measure is designed to reduce the carbon intensity of California fuel by at least 10 percent by the year 2020.

"Being dependent on one source of fuel leaves our economy and our national security vulnerable to price shocks and global events beyond our control. Reducing the carbon content of transportation fuels sold in California by just 10 percent means we will replace 20 percent of our gasoline consumption with lower-carbon fuels, more than triple the size of the state's renewable fuels market, and add 7 million alternative fuel vehicles to our roads," Schwarzenegger said.

Carbon dioxide is a key cause of global warming, officials said.