California is suing five of the largest oil and gas companies in the world, alleging that they engaged in a "decades-long campaign of deception" about climate change and the risks posed by fossil fuels that has forced the state to spend tens of billions of dollars to address environmental-related damages.

State Atty. Gen. Rob Bonta filed the lawsuit Friday in San Francisco County Superior Court alleging that Exxon Mobil, Shell, Chevron, ConocoPhillips, BP and the American Petroleum Institute have known since the 1950s that the burning of fossil fuels would warm the planet but instead of alerting the public about the dangers posed to the environment they chose to deny or downplay the effects.

“Oil and gas companies have privately known the truth for decades — that the burning of fossil fuels leads to climate change,” Bonta said in a statement, “but have fed us lies and mistruths to further their record breaking profits at the expense of our environment. Enough is enough.”

Several other states and dozens of municipalities, including cities and counties in California, have filed similar lawsuits in recent years.

“With our lawsuit, California becomes the largest geographic area and the largest economy to take these giant oil companies to court,” Bonta said. “From extreme heat to drought and water shortages, the climate crisis they have caused is undeniable. It is time they pay to abate the harm they have caused.”

Bonta is seeking to create a nuisance abatement fund to finance climate mitigation and adaptation efforts; injunctive relief to protect California’s natural resources from pollution, impairment and destruction; and to prevent the companies from making any further false or misleading statements about the contribution of fossil fuel combustion to climate change.

Attorneys for the oil companies could not immediately be reached for comment. But Chevron issued this statement early Sunday: "Climate change is a global problem that requires a coordinated international policy response, not piecemeal litigation for the benefit of lawyers and politicians."

A growing number of high-profile cases in state court helped pave the way for Bonta’s 135-page lawsuit to hold oil and gas companies financially responsible for their role in climate change and marketing products they know cause injury.

They include the record $246-billion settlement with Big Tobacco, and a $350-million settlement reached in 2019 that will provide funds to clean up toxic lead paint sold by manufacturers that knew it was poisonous.

“There is some commonality with earlier cases involving other major bad actors who hurt people and threatened their health with lead paint, tobacco and opioids,” Bonta said in an interview with The Times on Saturday. “But every industry is unique.”

The potential size of the mitigation fund he is pursuing remains to be determined.

“These defendants must be held accountable for the truths they shared in private while trying to undermine the science in public,” he said. “They cannot pass those costs onto the public, governments or our future.”

“It is going to be a very, very large number,” he added.

California’s complaint includes several examples of evidence demonstrating that the defendants have long known about the environmental threat posed by the use of fossil fuels.

For instance, in 1968, API and its members received a report from the Stanford Research Institute, which it had hired to assess the state of research on environmental pollutants, including carbon dioxide, according to the lawsuit. The report stated: “Significant temperature changes are almost certain to occur by the year 2000, and . . . there seems to be no doubt that the potential damage to our environment could be severe.”

In 1978, an internal Exxon memo stated that present "thinking holds that man has a time window of five to 10 years before the need for hard decisions regarding changes in energy strategies might become critical.”

California has spent tens of billions of dollars to adapt to climate change and address the environmental damage that has resulted so far, the complaint said, and it will have to spend far more than that in the years to come.

“For more than 50 years, Big Oil has been lying to us — covering up the fact that they’ve long known how dangerous the fossil fuels they produce are for our planet,” Gov. Gavin Newsom said Friday.

“California taxpayers,” he said, “shouldn’t have to foot the bill for billions of dollars in damage — wildfires wiping out entire communities, toxic smoke clogging our air, deadly heat waves, record-breaking droughts parching our wells.”

In 2019, Newsom  began calling for plans to phase out oil production in California, citing the increasingly harmful effects of global warming. His actions raised ire in petroleum company boardrooms, enraged Kern County officials and left small-town governments at the southern end of the San Joaquin Valley grappling with shrinking tax rolls.

Climate liability litigation is gaining momentum. Five California cities — San Francisco, Oakland, Santa Cruz, Richmond, Imperial Beach — and the counties of San Mateo, Marin and Santa Cruz have filed climate lawsuits against fossil fuel companies, and some of those cases are now proceeding toward trial in state court, according to the nonprofit Center for Climate Integrity.

California is the first oil-producing state to pursue such charges. “California’s decision to take Big Oil companies to court is a watershed moment in the rapidly expanding fight to hold major polluters accountable for decades of climate lies,” said Richard Wiles, president of the Center for Climate Integrity.

The scale of the “devastating public nuisance created by defendant's egregious misconduct is truly staggering,” according to the state's lawsuit,  and its consequences are “felt throughout every part of the state, across all ecosystems and communities.”

Exxon Mobil, Shell and Chevron, which is headquartered in San Ramon, Calif., alone market fossil fuel fuel products to California consumers through more than 3,000 petroleum service stations across the state, officials say.

The defendant companies and their trade association, the American Petroleum Institute, “are individually and collectively responsible for the emission of tons of greenhouse gasses,” the lawsuit says.

Greenhouse gases are largely byproducts of human use and combustion of fossil fuels to produce energy and petrochemical products. The primary greenhouse gas emitted as a result of human activities is CO2.

As greenhouse gases accumulate in the atmosphere, the Earth radiates less energy back to space, warming the average surface temperature. The result has been whiplashing shifts in extreme weather, longer droughts, flooding, sea level rise, ocean acidification and harmful effects to terrestrial and marine ecosystems.

California's lawsuit asserts, however, that since 1988, the 105-year-old petroleum institute has led organizations and campaigns on behalf of its 600 members “that have promoted disinformation about the climate impacts of fossil fuel products to consumers.” They include, it says, the Global Climate Coalition, Partnership for a Better Energy Future and Alliance for Climate Strategies.

In a statement, API Senior Vice President and General Counsel Ryan Meyers dismissed the complaint as “nothing more than a distraction from important national conversations and an enormous waste of California taxpayer resources.”

“Climate policy is for Congress to debate and decide,” he said, “not the court system.”

Kassie Siegel, director of the Center for Biological Diversity’s Climate Law Institute, welcomed the state's lawsuit as part of a far wider campaign to put pressure on toxic emitters within California’s vast industrial complex— and their executives — to testify about whether they misled the public.

“As the world’s fifth-largest economy, and the nation’s most populous state,” she said, “California is uniquely positioned to hold Big Oil accountable for its endless lies and malicious blocking of climate action.”

Kathy Mulvey, a spokeswoman for the Union of Concerned Scientists, agrees.

“California’s lawsuit reflects the growing body of evidence of what Exxon Mobil, Shell and other major oil and gas companies knew about the dangers of their products,” she said, “and the devastating harms that have resulted from their lies, obstruction and delay tactics.

“It’s past time for these companies to stop their greenwashing and disinformation campaigns and pay their fair share of the costs the climate crisis is imposing on Californians.”

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This story originally appeared in Los Angeles Times.