The environmental ministers of Canada and Mexico went to San Francisco last month to sign a global pact — drafted largely by California — to lower planet-warming greenhouse pollution. Gov. Jerry Brown flies to China next month to meet with climate leaders there on a campaign to curb global warming. And a battery of state lawyers is preparing to battle any attempt by Washington to weaken California’s automobile pollution emission standards.
As President Trump moves to reverse the Obama administration’s policies on climate change, California is emerging as the nation’s de facto negotiator with the world on the environment. The state is pushing back on everything from White House efforts to roll back pollution rules on tailpipes and smokestacks, to plans to withdraw or weaken the United States’ commitments under the Paris climate change accord.
In the process, California is not only fighting to protect its legacy of sweeping environmental protection, but also holding itself out as a model to other states — and to nations — on how to fight climate change.
“I want to do everything we can to keep America on track, keep the world on track, and lead in all the ways California has,” said Mr. Brown, who has embraced this fight as he enters what is likely to be the final stretch of a 40-year career in California government. “We’re looking to do everything we can to advance our program, regardless of whatever happens in Washington.”
Since the election, California has stood as the leading edge of the Democratic resistance to the Trump administration, on a range of issues including immigration and health care. Mr. Trump lost to Hillary Clinton here by nearly four million votes. Every statewide elected official is a Democrat, and the party controls both houses of the Legislature by a two-thirds margin. Soon after Mr. Trump was elected, Democratic legislative leaders hired Eric H. Holder Jr., the former attorney general, to represent California in legal fights with the administration.
But of all the battles it is waging with Washington, none have the global implications of the one over climate change.
The aggressive posture on the environment has set the stage for a confrontation between the Trump administration and the largest state in the nation. California has 39 million people, making it more populous than Canada and many other countries. And with an annual economic output of $2.4 trillion, the state is an economic powerhouse and has the sixth-largest economy in the world.
California’s efforts cross party lines. Arnold Schwarzenegger, who served as governor from 2003 to 2011, and led the state in developing the most aggressive pollution-control programs in the nation, has emerged as one of Mr. Trump’s biggest Republican critics.
Mr. Trump and his advisers appear ready for the fight.
Scott Pruitt, the Environmental Protection Agency chief, whom Mr. Trump has charged with rolling back Obama-era environmental policies, speaks often of his belief in the importance of federalism and states’ rights, describing Mr. Trump’s proposals as a way to lift the oppressive yoke of federal regulations and return authority to the states. But of Mr. Brown’s push to expand California’s environmental policies to the country and the world, Mr. Pruitt said, “That’s not federalism — that’s a political agenda hiding behind federalism.”
“Is it federalism to impose your policy on other states?” Mr. Pruitt asked in a recent interview in his office. “It seems to me that Mr. Brown is being the aggressor here,” he said. “But we expect the law will show this.”
In one of his earliest strikes, Mr. Trump signed an executive order in March aimed at dismantling the Clean Power Plan, President Barack Obama’s signature climate policy change. Much of the plan, which Mr. Trump denounced as a “job killer,” was drawn from environmental policies pioneered in California.
Mr. Brown has long been an environmental advocate, including when he first served as governor in the 1970s. He has made this a central focus as he enters his final 18 months in office. In an interview, he said the president’s action was “a colossal mistake and defies science.”
“Erasing climate change may take place in Donald Trump’s mind, but nowhere else,” Mr. Brown said.
The leadership role being embraced by California goes to the heart of what has long been a central part of this state’s identity. For more than three decades, California has been at the vanguard of environmental policy, passing ambitious, first-in-the-nation legislation on pollution control and conservation that have often served as models for national and even international environmental law.