The California Public Utilities Commission estimates that reaching that goal could propel energy costs to nearly 11% above what they would be from gas-fired energy plants.
While 30 other states have also set requirements for power companies to utilize more renewable energy, their mandates are far more modest. Obama has been unsuccessful in his efforts to persuade Congress to pass a national mandate, and the prospects for Washington embracing more California-style energy policies is unclear.
In his State of the Union address last month, the president implored Congress to take action to cut the nation's pollution. Though he did not outline specific initiatives, he said he would take executive action to protect the environment if Congress declined to act.
"If Congress won't act soon to protect future generations, I will," Obama said.
Brown, meanwhile, is taking his green message overseas. In April, he is scheduled to visit China on a weeklong trade mission and will make climate change a centerpiece of his activities there, his aides say.
His itinerary includes a visit to Guangdong, the nation's most populous province, and he will seek ways for California to cooperate with leaders there to reduce harmful emissions.
Meanwhile, the state's Air Resources Board, which regulates air pollution in California, is working with officials in the Canadian provinces of Quebec and British Columbia on a joint effort to expand California's carbon-trading market.
Some of the lobbying efforts seem to be finding their mark. During the governors' conference, Arkansas Gov. Mike Beebe, a Democrat, said he shared Brown's concerns about the changing climate.
"It's not going to get any better," said Beebe, who has created a commission to set pollution-reduction targets in his state. "I'm with Jerry."
Times staff writer Richard Simon in Washington contributed to this report.