California made no secret of its ambitions when it enacted a landmark law on global warming just over a decade ago. Progress here on slashing greenhouse gas emissions, the law said, would have "far-reaching effects by encouraging other states, the federal government and other countries to act."
Now the goal has become more critical than ever as President Trump rolls back national environmental regulations. No matter how hard California pushes, the country will fall short of its obligations under the Paris agreement on climate change unless more states try to keep pace.
So far, experts say, not enough is being done. A dozen states are emulating California's rules on tailpipe emissions, and even more are setting benchmarks for increasing renewable energy. But persuading them to adopt other, more ambitious policies, such as requiring polluters to pay fees through a cap-and-trade system, remains elusive despite years of efforts.
"I'm not giving up hope," Gov. Jerry Brown said in an interview. "But it has been difficult."
The gap in environmental policies between California and other states has quickly morphed into a source of international concern. The United States must slash emissions by at least 26% below 2005 levels by 2025 to hit its target in the Paris agreement. If other countries such as India don't see the world's largest economy upholding its end of the deal, the entire framework for averting the worst effects of global warming could collapse. On Thursday, U.S. Environmental Protection Agency Administrator Scott Pruitt called for an "exit" to the climate agreement.
"You could begin to see an unraveling of this coalition," said Robert Stavins, director of the Harvard Environmental Economics Program.
Meeting the Paris target was always going to be difficult — all of former President Obama's policies combined would not have been enough to sufficiently slash emissions by the deadline, according to research from the Lawrence Berkeley National Laboratory. However, Trump is targeting regulations on power plants and vehicles, knocking the country further off the trajectory toward its international obligations.
"We're not close," said Kate Larsen, an Oakland-based director at the Rhodium Group, which tracks climate policies. "There still needs to be a lot more from many other states to hold off the damage from the Trump administration."
The lack of pressure from the White House could have a ripple effect that makes states less likely to take politically difficult steps to cut emissions and reduce their reliance on fossil fuels. But Brown and environmental advocates are hoping for a political backlash against Trump that helps persuade local leaders to fill the void created at the federal level on climate change.
"I do believe that science and peer-reviewed research — and essentially the truth about the world — will ultimately prevail," Brown said. "The only question is if it will be too late."
California is responsible for less than 1% of the world's greenhouse gas emissions, and Brown has pledged to keep looking for allies.
That effort has advanced in fits and starts ever since his predecessor, Gov. Arnold Schwarzenegger, signed Assembly Bill 32 in 2006. The law became the foundation for California's cap-and-trade program, which requires companies to buy permits to release greenhouse gases into the atmosphere.
California and some of its neighbors launched the Western Climate Initiative to support similar policies in the region. But the recession made politicians wary of anything that could increase costs on businesses, and then legislation for a national cap-and-trade program died in Congress. Meanwhile, Democrats lost campaigns in states including Arizona and New Mexico.
"When those [states] went Republican, we lost them," said Terry Tamminen, who led the California Environmental Protection Agency under Schwarzenegger.
In 2013, California signed a new agreement with Oregon, Washington and British Columbia to create a West Coast alliance. However, progress has been difficult, even in the otherwise liberal Pacific Northwest.
Oregon, which has one of the only statehouses completely controlled by Democrats, is debating a cap-and-trade program that could link with California, creating new avenues for ratcheting down emissions. But the state's budget problems may push climate change onto the back burner in the Legislature.
"When you have schools and roads on the docket, it doesn't take priority," said Kristin Eberhard, a Portland-based senior researcher at the Sightline Institute.
There are other hurdles in Washington, where Republicans have often been able to block climate programs. Lawmakers are considering a tax on carbon emissions rather than requiring polluters to obtain permits through a cap-and-trade system, an idea that previously died in the state Legislature.
"This is the hardest thing to do," said Vlad Gutman-Britten, the Washington director at Climate Solutions, an advocacy group. "The state is definitely acting on climate. It's a matter of seeing what the suite of policies are."
Domestic political obstacles mean it can be easier for California to find partners outside the country. The Canadian province of Quebec has linked with California on cap and trade to collectively auction pollution permits, expanding the program's economic footprint, and Ontario is expected to take a similar step. China has worked with California to develop its own system, which is scheduled to launch this year.
Environmental advocates say changing the landscape will mean increasing their pressure in statehouses, which are mostly controlled by Republicans.
"The same political forces and money that are behind the retreat away from climate action in Washington are also present in states around the nation," said Jeremy Symons, associate vice president for climate political affairs at the Environmental Defense Fund. "It's going to take the inevitable public backlash that we expect, and are already starting to see, to turn things around."
He pointed to progress in some states led by Republicans, who see potential for new jobs and lower prices in renewable energy. Since Trump won election, Illinois Gov. Bruce Rauner and Michigan Gov. Rick Snyder signed legislation boosting solar and wind power in their states. More recently, Ohio Gov. John Kasich vetoed a measure to eliminate similar policies that was pushed by members of his own party.
There are other areas where California is prepared to anchor the battle against climate change. It's the only state in the country allowed to set tougher rules on tailpipe pollution than federal standards, and regulators here are pushing forward on cutting emissions despite potential opposition from Trump.
The decision could affect nearly half of the country's vehicle market because a dozen states have adopted California's policies as their own.
"Just go to an auto show," said Bonnie Reiss, who worked on climate legislation for Schwarzenegger and now manages the former governor's institute at the University of Southern California. "Every single car manufacturer has cool hybrids or electric cars."
Brown has also emphasized his partnership with New York Gov. Andrew Cuomo. Combined, their two states represent one-fifth of the country's economy, and they've set similar targets for reducing emissions.
When Trump announced his decision to roll back Obama's Clean Power Plan last month, Brown and Cuomo pledged to keep fighting climate change "with or without Washington."
It's the kind of message that environmental advocates want to see more often in the coming months.
"If states like California and New York are out there and showing the world that we're pushing forward," Larsen said, "that will send a huge signal to the international community."