California's lawsuit says oil giants downplayed climate change. Here's what to know

In this aerial picture taken on Aug. 21, a vehicle drives through floodwaters following heavy rains from Tropical Storm Hilary in Thousand Palms, Calif. Josh Edelson/AFP via Getty Images hide caption

toggle caption Josh Edelson/AFP via Getty Images

In this aerial picture taken on Aug. 21, a vehicle drives through floodwaters following heavy rains from Tropical Storm Hilary in Thousand Palms, Calif.

Josh Edelson/AFP via Getty Images

The state of California has filed a sweeping climate lawsuit against Exxon Mobil, Shell, BP, ConocoPhillips, and Chevron, as well as the domestic oil industry's biggest lobby, the American Petroleum Institute.

, filed on Friday in San Francisco Superior Court, claims that the companies misled the public for decades about climate change and the dangers of fossil fuels. It demands the companies help fund recovery efforts related to California's extreme weather events, from rising sea levels to drought and wildfires, that have been supercharged by human-caused climate change.

"Oil and gas companies have privately known the truth for decades — that the burning of fossil fuels leads to climate change — but have fed us lies and mistruths to further their record-breaking profits at the expense of our environment. Enough is enough," Rob Bonta, California's attorney general, said Saturday in a .

Oil giants are already facing dozens of lawsuits from states and localities over their role in causing climate change. California's case adds to the legal threats facing America's oil and gas industry, forcing fossil fuel companies to defend themselves against the largest economy in the U.S. and a major oil-producing state.

On Sunday, California Gov. Gavin Newsom said the damage caused by oil and gas companies' deceit was "incalculable" and his state is prepared to enforce accountability.

"The scale and scope of what the state of California can do, we think can move the needle," Newsom said at a discussion organized by Climate Week NYC.

Why now?

The lawsuit comes after years of extreme weather events have battered California's economy and killed its residents. In just the past year, California has been inundated with record heat, , unusual bouts of severe rain and snow, and a rising sea level that's threatened the state's shorelines — disasters that studies say were made more likely or more intense due to climate change.

California filed its lawsuit against Exxon and other oil and gas companies just a day afterreported that executives at Exxon continued in recent years to raise doubts internally about the dangers of climate change and the need to cut back on oil and gas use, even as the company publicly conceded that burning fossil fuels contributes to global warming.

Those efforts inside of Exxon, which continued until 2016, according to the, were happening at the same time that scientists at the company were modeling troubling increases in carbon dioxide emissions without big reductions in fossil fuel consumption. The cited internal company documents that were part of a New York state lawsuit and interviews with former executives.

In response to the article, an Exxon spokesperson told NPR that the company has repeatedly acknowledged that "climate change is real, and we have an entire business dedicated to reducing emissions — both our own and others."

Similarly, Shell spokesperson Anna Arata said that the company agrees climate change needs to be addressed, but it should be done collaboratively not by legal action.

"We do not believe the courtroom is the right venue to address climate change, but that smart policy from government and action from all sectors is the appropriate way to reach solutions and drive progress," she said in a statement.

Chevron agreed that climate change policy requires coordination. The company also accused California of being "a leading promoter of oil and gas development."

Exxon worked for decades to create confusion about climate change, even though its own scientists had begun warning executives as early as 1977 that carbon emissions from burning fossil fuels were warming the planet, posing dire risks to human beings.

A study early this year in the journal found that Exxon's scientists had modeled global warming trends with "shocking levels of skill and accuracy," .

Despite the warning from its own scientists, Exxon spearheaded and funded a highly effective campaign for more than 30 years that cast doubt on human-driven climate change and the science underpinning it.

Scientists with the United Nations to prevent global warming that would cause more dangerous impacts, like storms and heat waves. Climate scientists say people need to Celsius (2.7 degrees Fahrenheit). The world is currently heading for about 2.5 degrees Celsius of warming.

Climate change is . Over the past two years, the threat of wildfires has led several big insurance companies to in the state or to stop selling new policies altogether in order to avoid paying billions in damages.