Environmentalists are celebrating two new lawsuits filed by the cities of Oakland and San Francisco, California, in attempts to hold some of the world's largest oil companies to account for fueling climate change.

"It's time to hold these climate deadbeats accountable.... These climate impacts are here now, and we know who's responsible."

—Naomi Ages, Greenpeace

"It's time to hold these climate deadbeats accountable," said Greenpeace's climate liability campaigner Naomi Ages, after the suits were announced this week.

"In the past two weeks there have been five climate-fueled hurricanes, devastating communities from Houston to Puerto Rico and beyond," she continued. "These climate impacts are here now, and we know who's responsible."

San Francisco's city attorney, Dennis Herrera, expressed a similar sentiment. "The bill has come due," he told SFGate. "It's time for these companies to take responsibility."

While communities bordering the Atlantic have been battered by record-breaking storms—which scientists say were intensified by climate change—massive wildfires have ravaged the northwestern United States in recent weeks. Meanwhile, the coastal communities of Oakland and San Francisco are battling increased flooding, coastal erosion, and property damage from rising sea levels and other effects of global warming.

The cities' lawsuits allege—supported by modern climate science—that major oil and natural gas companies contribute substantially to global warming by extracting and using fossil fuels, which emit massive quantities of heat-trapping greenhouse gases into the atmosphere, causing ocean waters to warm and ice sheets to melt, and thus, sea levels to rise, endangering coastal communities.

Further, the suits allege that these companies—BP, Chevron, ConocoPhillips, ExxonMobil, and Shell—have known for decades that using fossil fuels drives global warming, and yet they not only have continued to do so, but also have intentionally deceived the public regarding the consequences.

"Defendants stole a page from the Big Tobacco playbook and sponsored public relations campaigns, either directly or through the American Petroleum Institute or other groups, to deny and discredit the mainstream scientific consensus on global warming, downplay the risks of global warming, and even to launch unfounded attacks on the integrity of leading climate scientists," the San Francisco suit reads.

"It is appropriate that people are now looking to the courts, instead of legislators, to help hold fossil fuel companies accountable for their contributions to sea level rise and other climate impacts."

—Ken Kimmell, Union of Concerned Scientists

The cities are seeking billions of dollars in compensation for both past and future damage caused by climate change. They plan to use any money they are awarded through the courts to finance improvements to infrastructure.

"The harm to our cities has commenced and will only get worse," Oakland's city attorney Barbara Parker told SFGate.

Ken Kimmell, president of the Union of Concerned Scientists, praised the cities in California for taking a "bold and necessary step to protect their communities."

"It is appropriate that people are now looking to the courts, instead of legislators, to help hold fossil fuel companies accountable for their contributions to sea level rise and other climate impacts," Kimmell told the East Bay Times.

These suits, which were filed in state court, are part of "a growing body of legal action against oil companies over climate change," Reuters notes. "Prosecutors for New York and Massachusetts are investigating Exxon, for example, over the possibility it misled investors in public statements on the risks of climate change."

The suits also follow three similar public nuisance lawsuits filed earlier this year by Marin and San Mateo Counties, and the city of Imperial Beach, in San Diego County.

As Ages of Greenpeace said: "There are now five California lawsuits that, if successful, will help protect people's lives, livelihoods, and property from the devastating impacts of climate-fueled extreme weather events."