Gov. Jerry Brown on Friday announced a sweeping new environmental initiative to cap his final year in office, signing an executive order that commits the state to a goal of 5 million zero-emission vehicles on the road by 2030.

The ambitious target dwarfs his previous goal of 1.5 million EVs by 2025, and includes a plan to spend $2.5 billion in new funding to encourage motorists to buy them. And it comes as the Golden State is leading the way on taking aggressive measures to fight global warming as the Trump administration moves to dial back the country’s commitment to combat climate change.

Right now, with Teslas, Nissan Leafs and other electric cars becoming a fixture on Bay Area and L.A. freeways, California has about 350,000 electric vehicles, far more than any other state. But hitting Brown’s new goal — a nearly 15-fold increase from current levels — will be a major challenge.

Brown’s order means that a huge state investment in charging stations, along with more tax credits, rebates and other initiatives, will be needed in the next decade. Transportation is the largest source of greenhouse gases in California, accounting for about 39 percent of the total, with most of that coming from passenger cars and SUVs.

Brown hinted at the new plan on Thursday during his State of the State speech, but his message was lost on most observers in a speech filled with myriad topics, from prison reform to health care.

“The goal is to make our neighborhoods and farms healthier, our vehicles cleaner — zero emission the sooner the better — and all of our technologies increasingly lowering their carbon output,” Brown said in Thursday’s speech.

“We’ve all got a lot of work. And think of all the jobs, and how much cleaner our air will be then.”

The earth’s climate continues to warm, and Brown has made the issue a focus of his current term as governor. The 10 hottest years since 1880, when modern temperature records began, have all occurred since 1998, according to NASA. And last year, California suffered deadly heat waves and record wildfires, from Napa and Sonoma counties to Santa Barbara.

Doubling down on goals set by his predecessor, Gov. Arnold Schwarzenegger, Brown in recent years has signed laws committing the state to generating 50 percent of its electricity from renewable sources like solar and wind by 2030, and cutting greenhouse gas emissions 40 percent from 1990 levels by 2030.

To reach the second goal, much more must be done to reduce the amount of gasoline California burns, experts say.

“There is no way on earth they can reach their greenhouse gas goals unless they do something to force a lot more electric vehicles in the mix,” said James Sweeney, director of the Precourt Energy Efficiency Center at Stanford University. “That’s the reality. I don’t think they will be able to meet the goals even if they do force a lot more electric vehicles in the mix because there are all of the existing vehicles on the road.”

Brown’s order on Friday lays out an eight-year plan for the state to spend $2.5 billion between now and 2025, dramatically expanding the number of electric vehicle charging stations from roughly 14,000 now to 250,000. The number of high-speed charging stations would increase from roughly 1,500 now to 10,000, and the number of hydrogen fueling stations would jump statewide from 31 now to 200 in 2025.

Much of the money, $1.6 billion, would come from proceeds from the state’s cap-and-trade auctions and would fund vehicle rebates. The other $900 million would come largely from an existing $2 fee on vehicle registration first approved by Schwarzenegger for clean air programs and would fund charging stations, many built in partnership with private companies.

Zero-emission vehicles, called “ZEVs” by bureaucrats and policy wonks, include electric cars, buses and trucks that run on batteries only. The category also includes plug-in hybrid vehicles that run on electricity but have small gasoline engines, like the Chevy Volt, the BMW 740e and the Chrysler Pacifica mini-van. And they include fuel cell vehicles that run on hydrogen gas, like the Honda Clarity or Toyota Mirai.

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Environmentalists cheered Friday’s news.

“The governor is basically going big before he goes home,” said Simon Mui, a senior scientist with the Natural Resources Defense Council, a nonprofit environmental advocacy group. “What he’s laying out is a foundation to move California away from fossil fuels and internal combustion engines.”

The auto industry gave general support Friday for the new plan. The industry has clashed over the past 50 years with California regulators who banned leaded gasoline, mandated smog checks and relentlessly tightened engine rules to reduce air pollution after Gov. Ronald Reagan first created the California Air Resources Board in 1967. But it particularly likes the fact that Brown’s executive order continues to provide rebates for Californians who purchase electric cars and funds charging stations.

“While we’ll surely have questions that we’ll need clarification for, we’re pleased to see that Gov. Brown has committed to an ambitious program to develop desperately needed infrastructure and a consistent incentive program that will give customers the confidence and encouragement to purchase zero-emission vehicles (ZEVs),” said Curt Augustine, vice-president of the Alliance of Automobile Manufacturers. “Meeting California’s climate goals is a partnership.”

Although they produce no tailpipe pollution and help reduce smog and global warming emissions, electric cars have not yet caught on in a broad way in California. Only 5 percent of the state’s annual vehicle sales are electric cars. Gasoline is still relatively cheap compared to many other countries. Charging stations are not yet widespread in every California city. And many new electric cars cost considerably more than gasoline-powered vehicles.

Mary Nichols, head of the California Air Resources Board, said Friday that if the plan is successful, 40 percent of new car sales in 2030 will be zero-emission vehicles. That may sound far-fetched, but Volvo announced recently that every new car it makes after 2019 will have an electric motor, and several European countries, including France, have passed laws to ban gasoline engines on all new cars by 2040.

But California could face another speed bump: Brown leaves office next January, and there are no guarantees that the next governor or state lawmakers will continue funding the $2.5 billion effort.

“We’ve enjoyed great support from past governors, as well as this one, for air quality programs in the state of California, and I don’t think there’s likely to be a slacking off in the next administration,” Nichols said. “We’re hoping it will be maintained and the logic of it will be compelling.”