Big Oil faces mounting lawsuits as extreme weather worsens, with California leading efforts to make fossil fuel giants pay billions of dollars for the climate damage they have long denied.

Across the country, states, cities, tribes and environmental groups have filed dozens of lawsuits against oil companies alleging that they misled the public about the dangers of their products. These cases share a core argument: Oil companies knew fossil fuels were driving climate change and lied about it.

California and other plaintiffs are recycling a legal strategy deployed during the 1990s, when states alleged that tobacco companies knew cigarettes cause cancer. Four large companies settled the cases by paying billions to fund states’ anti-smoking campaigns and other efforts. The manufacturers also must make annual payments to the states as long as they sell cigarettes in the United States.

The settlement set a powerful precedent for using litigation to hold industries accountable for public harm caused by deceptive practices.

“All of these (climate) cases are fundamentally deception cases,” said Benjamin Franta, a professor of climate law at University of Oxford and leader of its Climate Litigation Lab.

For decades, climate cases leaned on environmental laws and regulations rather than corporate accountability, Franta said. But with deception cases, “you can go directly after the private companies,” he said, and “the damages could be enormous.”

But while tobacco lawsuits proved corporations can be held accountable, legal experts say taking on Big Oil presents bigger hurdles.

Michael Gerrard, an environmental law expert at Columbia Law School, said the oil industry, unlike the tobacco industry, is actively supported by government policies, from subsidies to infrastructure investments, that promote oil consumption.

“There are a lot of lawsuits pending, but so far, not a single court in the world has held fossil fuel companies financially responsible for greenhouse gas emissions,” Gerrard said. “It’s highly uncertain whether these cases will ultimately succeed.”

Oil companies say holding them accountable for climate change makes them responsible for an entire economy that depends on their products — a defense that has found traction in some state courts.

“It’s not the oil and gas companies that are actually the direct polluters,” Gerrard said. Liability may have to be assigned along a vast supply chain, from refiners to power plants — even consumers who buy the gasoline, plastics and other products produced from fossil fuels, he said.

“There are a lot of lawsuits pending, but so far, not a single court in the world has held fossil fuel companies financially responsible for greenhouse gas emissions. It’s highly uncertain whether these cases will ultimately succeed.”
— Michael Gerrard, Columbia Law School

Also, while the connection between climate change and fossil fuels has been clearly documented by scientists, the evidence is less definitive linking fossil fuels to specific extreme weather events such as droughts or wildfires. And climate-warming greenhouse gases are global in scope and emitted by a variety of fossil fuels and other sources, not just gasoline and other products manufactured by the oil industry.

In one closely watched climate case in Hawaii, 20 states, including Texas, Wyoming and Alaska, threw their weight behind the oil industry, which asked the U.S. Supreme Court to intervene. The court in January denied that request.

Still, climate liability efforts are gaining traction in some areas, especially in California, following January’s devastating wildfires in Los Angeles.

State Sen. Scott Wiener, a Democrat from San Francisco, introduced a bill in January that would give homeowners and insurance companies new rights to sue oil companies for climate disasters. Sen. Caroline Menjivar, a Democrat from Van Nuys, reintroduced a version of a bill that failed last year, requiring companies to pay for the damage greenhouse gas emissions have caused in California since 1990.

A test case in Honolulu

Climate plaintiffs recently notched a win in January when the U.S. Supreme Court denied a request by the oil industry to intervene in the Hawaii lawsuit, allowing cases in state courts to move forward for now. The city and county of Honolulu filed suit in 2020 seeking unspecified damages from Sunoco LP, Exxon Mobil and other oil companies.

In its appeal to the Supreme Court, the oil industry, supported by 20 states, maintained that federal law precludes states’ rights to seek damages from greenhouse gases, which are emitted worldwide. The states, led by Alabama, said Honolulu is violating their rights by “asserting the power to enact disastrous global energy policy via state tort law. Among their demands is that major energy companies stop ‘promoting the sale and use’ of their fuel products.”

The Biden administration argued that the Supreme Court should let the Hawaii proceedings play out in state court.

“The oil companies would love to have this court decide right now that all of these cases should be thrown out. Well, they didn’t get that,” said Pat Parenteau, a law professor at the Vermont Law and Graduate School who specializes in climate policy. “So now it’s a case-by-case battle until they can get one of these cases back to the Supreme Court — that’s what their end game is.”

After surviving multiple dismissal attempts, Honolulu’s lawsuit is the furthest along of any state climate lawsuits. The case is entering full discovery, meaning oil companies could soon need to turn over documents and sit for depositions that could be illuminating about their role in climate change, said Corey Riday-White, a managing attorney at the Center for Climate Integrity, which supports efforts to challenge oil companies in court and sponsored Wiener’s legislation.

If a jury delivers a big verdict in the Honolulu case, the pressure to settle will mount, experts say. But the case would almost certainly be appealed to the U.S. Supreme Court, where many justices are seen as favorable to corporate interests. President Donald Trump’s Justice Department is likely to support oil companies.

“Now it’s a case-by-case battle until they can get one of these cases back to the Supreme Court — that’s what (industry’s) end game is.”
— Pat Parenteau, Vermont Law and Graduate School

One major hurdle for climate suit plaintiffs is the industry’s push to move cases to federal courts, where judges have been more inclined than state courts to dismiss them, legal experts said. State courts also have dismissed some recent cases.

California has played a major role in the litigation. In 2023, California Attorney General Rob Bonta sued ExxonMobil, Shell, BP, ConocoPhillips, Chevron and the American Petroleum Institute, alleging that they misled the public about climate change. The suit, filed in San Francisco Superior Court, seeks unspecified damages, penalties and the establishment of an abatement fund to cover future costs.

Franta noted that California’s case could be a game changer.

“California’s case is among the most important,” said Franta of the Climate Litigation Lab. “It’s an enormous jurisdiction, and bringing a very muscular claim against many companies, and under different causes of action. And of course we know there’s a lot of climate-related damages — economic damages and property damages — in California.”

If successful, these cases could set a precedent similar to the tobacco cases, ultimately holding fossil fuel companies accountable.

The American Petroleum Institute did not respond to a request by CalMatters for comment, but in 2023 called California’s lawsuit “meritless” and “politicized,” adding that climate policy should be legislated in Congress and not decided in the courts.

“California’s case is among the most important. It’s an enormous jurisdiction…and we know there’s a lot of climate-related damages — economic damages and property damages — in California.”
— Benjamin Franta, Oxford University’s Climate Litigation Lab

Last year, a judge approved a request by Bonta to coordinate with multiple other California jurisdictions that had sued the oil industry on similar grounds.

Evidence of industry deception

Plaintiffs argue that oil companies misled the public about climate change, and there’s strong evidence they did. But proving those deceptions influenced consumer behavior — or that a better-informed public would have acted differently — is far from straightforward.

“Would they have stopped filling their tanks if a sign at the gas pump said, ‘This fuel contributes to climate change?’” Gerrard asked.

Many experts mark the wave of climate litigation as beginning in 2017, when San Francisco, Oakland and other California municipalities sued major oil companies for deceptive practices, marking a shift from earlier, largely unsuccessful federal claims.

For years, plaintiffs filing climate cases relied on environmental laws and regulations . But now they are focusing on allegations of deception.

Internal documents reveal that by the 1960s, oil companies began predicting fossil fuels could drive catastrophic climate change. Yet, in later decades, as scientists increasingly came to the consensus that burning fossil fuels caused climate change, oil companies ran ads, filed reports and lobbied lawmakers to spread the opposite message — that climate change wasn’t real or wasn’t a big deal.

In the 1970s, Exxon had internal climate research predicting today’s global warming with stunning accuracy. By the early 1980s, the industry knew what was happening, how severe it would be and that fossil fuels were the cause. A pivotal moment came in 2015 when investigative journalists exposed what the industry knew.

Tobacco industry suits focusing on deception also paved the way for lawsuits against other large industries, including opioid manufacturers, big banks after the housing crash and chemical companies for polluting water with “forever chemicals.”

Heat waves and wildfires

In the meantime, the science that links climate change to specific effects has evolved rapidly, now churning out real-time assessments of how much climate change has worsened a given disaster.

The science has changed from one of uncertainty to precise statements like a specific hurricane’s “rainfall was made 40% worse by climate change,” said Kristina Dahl, vice president for Science at Climate Central, which works on quantifying how much climate change is worsening extreme weather.

Because of the evolving science, some cases are also getting more specific. In Oregon’s Multnomah County, a lawsuit against Exxon Mobil Corp. and other oil and gas companies zeroes in on the Pacific Northwest’s devastating 2021 heat wave, attempting to link its deadly impact to climate change and seeking $1.55 billion in damages and a $50 billion abatement fund.

Connecting wildfires to fossil fuel companies is particularly difficult, since fires are often ignited by identifiable parties, such as utilities or arsonists, who can be held directly liable.

Former California Insurance Commissioner Dave Jones has spent years trying to get the insurance industry to acknowledge the financial risks of climate change. But while insurers are quick to pull out of high-risk areas and raise rates, they’ve been far less willing to hold oil companies accountable for the disasters their emissions are fueling.

The insurance industry is facing an existential crisis, Jones said. Wildfires, hurricanes and even newly emerging threats like severe convective storms are making it harder to insure homes and businesses.

Insurance companies are still heavily invested in the industry driving it. According to Jones, U.S. insurers have over half a trillion dollars tied up in fossil fuels.

If oil companies are held financially responsible for disasters, Gerrard of Columbia Law School warned that equity firms or foreign companies with even less concern for climate issues could swoop in.

“If the companies go bankrupt, they’ll be bought by firms that will be happy to drill,” Gerrard said.

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