California and Big Oil are parting ways after their century-long affair

California divorces itself from fossil fuels as Exxon Mobil and Chevron disclose a $5 billion writedown of assets.

It is the end of an era for Big Oil in California, as the most populous U.S. state divorces itself from fossil fuels in its fight against climate change.

California’s oil output a century ago amounted to it being the fourth-largest crude producer in the U.S., and spawned hundreds of oil drillers, including some of the largest still in existence. Oil led to its car culture of iconic highways, drive-in theatres, banks and restaurants that endures today.

On Friday, however, the marriage will officially end. The two largest U.S. oil producers, Exxon Mobil and Chevron, will formally disclose a combined $5 billion writedown of California assets when they report fourth-quarter results.

“They are definitely getting a divorce,” said Jamie Court, president of advocacy group Consumer Watchdog, which said the companies long ago stopped investing in California production, and now want to hive off their old wells there. “They’ve been separated for more than a decade, now they are just signing the papers.”

Exxon Mobil last year exited onshore production in the State, ending a 25-year-long partnership with Shell PLC , when they sold their joint-venture properties.

The State’s regulatory environment has impeded efforts to restart offshore production, Exxon said this month, leading to an exit that includes financing a Texas company’s purchase of its offshore properties.

The No.1 U.S. oil producer’s asset writedown will cost about $2.5 billion and officially end five decades of oil production off the coast of Southern California.