Could California ban gasoline cars?

California Gov. Jerry Brown has expressed interest in banning cars that burn fossil fuels, the state’s top climate change regulator said in an interview published Tuesday.

“I’ve gotten messages from the governor asking, ‘Why haven’t we done something already?’” Mary Nichols, chair of the California Air Resources Board, said in an interview with Bloomberg News.

California has, for years, pushed automakers to offer cars that produce no emissions, turning the state into the nation’s largest market for electric cars. It has not, however, proposed an outright ban on cars running on the internal combustion engine.

Other governments have.

France and Britain will bar sales of new gasoline and diesel vehicles by 2040. Norway is aiming for 2025, even though the country remains a major oil producer. India has targeted 2030. Chinese officials are working on a ban but have not announced a timetable.

“The governor has certainly indicated an interest in why China can do this and not California,” Nichols told Bloomberg.

The governor’s press office referred questions Tuesday to the air board, which runs most of California’s climate change programs. A board spokesman declined to say whether a ban was under active discussion, and if so, when it might take effect.

“Given the existential challenge we face, the administration is looking at many, many possible measures — including additional action on electric vehicles — to help rapidly decarbonize the economy and protect the health of our citizens,” spokesman Dave Clegern said in an email.

The board’s own projections suggest California will need to phase out new fossil fuel-burning vehicles by midcentury if the state hopes to meet its climate goals. Many Democratic leaders in Sacramento also want California to achieve 100 percent renewable electric power, but a bill to do so by 2045 died in the Legislature this year.

California law calls for trimming greenhouse gas emissions back to 1990 levels by 2020, then cutting them another 40 percent by 2030. By 2050, state officials want emissions slashed to 80 percent below 1990 levels, though that goal is not enshrined in law.

One board analysis found that zero-emission vehicles — such as electric cars and hydrogen fuel-cell vehicles — would need to make up nearly 100 percent of new vehicle sales in the state by 2040to hit that 2050 emissions target.

“Timing matters,” said Simon Mui, director of the California vehicles and fuels program at the Natural Resources Defense Council, an environmental group. “By 2050, the phaseout of combustion technologies is needed to meet our climate goals.”

Cars and trucks represent California’s biggest source of greenhouse gas emissions by far. In 2015, the last year for which complete data are available, on-road transportation produced 34 percent of the state’s total emissions, according to the air board’s data.

California regulations already force automakers to ensure that a percentage of the cars they sell in the state produce zero emissions. Those that can’t meet the target, or choose not to, can buy credits from other automakers, such as Palo Alto’s Tesla, that sell zero-emission vehicles.

More than 157,000 electric cars are now registered in California, roughly half of all such cars nationwide. But they remain a small fraction of cars on the road.

Automakers note that customers have been slow to embrace electric cars, which cost more than comparable gas-burning models. And although some new electric cars — notably the Chevy Bolt and the Tesla Model 3 — can go more than 200 miles on a fully charged battery, most have ranges up to 100 miles.

A full ban on fossil-fuel vehicles in California, which represents 12 percent of all auto sales nationwide, would jolt the industry.

“We have been working with California on intelligent, market-based approaches to emissions reductions beyond 2025, and we hope that this doesn’t signal an abandonment of that position,” John Bozzella, president of the Association of Global Automakers trade group, said in an email Tuesday. “To reach our goals, we will need continued investment in new technologies, the infrastructure to support them, and, perhaps most importantly, consumers who will want to buy them.”