Senator Fran Pavley, a Los Angeles-area Democrat who wrote the 2006 legislation and one of the bills passed this week, said that much had changed in the past decade and that state lawmakers were no longer debating the potential effect of climate change.

“People once thought we were being alarmist when we talked about drought and year-round wildfires,” she said. “But all these predictions have come true, and the realities of climate change seem to be accelerating and are tangibly visible sooner than I ever expected. The discussion here now is how to address it, not if.”

The legislation does not address the struggling cap-and-trade program. The program is facing a lawsuit from the California Chamber of Commerce, which contends that the tax is unconstitutional.

Mr. Brown has suggested that he would consider a ballot initiative to get voter approval of the program. It has brought in far less revenue than expected in the most recent auctions, which require companies to buy credits to release greenhouse gas emissions.

John Sterman, a professor and climate policy expert at the MIT Sloan School of Management, said California’s move sent an unambiguous message that major political forces support such action. “It says, We’re committed to this task,” he said. “We’re not going back.”

In a practical sense, Dr. Sterman said, the decision gives companies and innovators clear direction about how to make investments. That could lead companies to drive down their prices in alternative energies, he said.

Still, Dr. Sterman said, even California’s ambitious goals fall short of what will ultimately be needed to head off severe effects of climate change. “As welcome as California’s action is, it’s still not aggressive enough,” he said.