• Multnomah County in Oregon is suing oil and gas companies Exxon Mobil, Shell, Chevron, BP, ConocoPhillips and related organizations for the damages caused by the 2021 Pacific Northwest heat dome.
• The heat caused 69 people to die, property damage and was a draw on taxpayer resources, Multnomah County says.
• Multnomah County is seeking $50 million in actual damages, $1.5 billion in future damages, and an estimated $50 billion for an abatement fund to "weatherproof" the city, its infrastructure and public health services in preparation for future extreme weather events.
• The defendants in the case largely say the lawsuit is unproductive and won't help make change.

Multnomah County in Oregon is suing oil and gas companies Exxon Mobil, Shell, Chevron, BP, ConocoPhillips and related organizations for the damages caused by the 2021 Pacific Northwest heat dome. Multnomah County said these and other fossil fuel companies and entities operating in the region are significantly responsible for causing and worsening the deadly heat event.

"The combined historical carbon pollution from the use of Defendants' fossil fuel products was a substantial factor in causing and exacerbating the heat dome, which smothered the County's residents for several days," Multnomah County alleges, according to a written statement released Thursday.

The lawsuit is filed against Anadarko Petroleum (acquired by Occidental Petroleum in 2019), American Petroleum Institute, BP, Chevron, ConocoPhillips, Exxon Mobil, Koch Industries, Marathon Petroleum, McKinsey & Company, Motiva, Occidental Petroleum, Peabody Energy, Shell, Space Age Fuel, Total Specialties USA, Valero Energy and Western States Petroleum Association.

Multnomah County is seeking $50 million in actual damages, $1.5 billion in future damages, and an estimated $50 billion for an abatement fund to "weatherproof" the city, its infrastructure and public health services in preparation for future extreme weather events.

Starting on June 25, 2021, Multnomah County had three consecutive days where the heat reached 108, 112 and 116 degrees Fahrenheit, respectively. Each of those days was about 40 degrees above the regional average and were the hottest days in the County's recorded history.

The heat event is called a heat dome which is a weather event caused by a high-pressure system that in this case prevented cooler maritime winds to blow and also prevented clouds from forming.

The heat caused the deaths of 69 people, and property damage and was a draw on taxpayer resources, Multnomah County says.

Multiple climate scientists researched the cause of the heat dome and all said that the event was caused by excessive carbon dioxide emissions released by the burning of fossil fuels, the plaintiff says.

"The heat dome that cost so much life and loss was not a natural weather event. It did not just happen because life can be cruel, nor can it be rationalized as simply a mystery of God's will," the lawsuit reads. "Rather, the heat dome was a direct and foreseeable consequence of the Defendants' decision to sell as many fossil fuel products over the last six decades as they could and to lie to the County, the public, and the scientific community about the catastrophic harm that pollution from those products into the Earth's and the County's atmosphere would cause."

Jessica Vega Pederson, the chair of Multnomah County, is seeking to protect the residents of the county she represents.

"This lawsuit is about accountability and fairness, and I believe the people of Multnomah County deserve both. These businesses knew their products were unsafe and harmful, and they lied about it," Pederson said in a written statement announcing the lawsuit. "They have profited massively from their lies and left the rest of us to suffer the consequences and pay for the damages. We say enough is enough."

The case is being brought by three law firms with expertise in catastrophic harm litigation: Worthington & Caron PC, Simon Greenstone Panatier PC, and Thomas, Coon, Newton & Frost.

The plaintiffs allege the defendants committed negligence and fraud and created a public nuisance.

"There are no new laws or novel theories being asserted here. We contend that the Defendants broke long-standing ones, and we will prove it to a jury," Jeffrey Simon, a partner at Simon Greenstone Panatier, said in a statement. 

The case is using new and expert climate science, according to Roger Worthington, a partner at Worthington & Caron.

"We will show that the normal use of fossil fuel products over time has imposed massive external, unpriced and untraded social, economic and environmental costs on the County. We will show that they were aware of this price, and instead of fully informing the public, they deceived us. And we will ask a jury to decide if it is fair to hold the polluters accountable for these avoidable and rising costs," Worthington said in a written statement.

"We are confident that, once we show what the fossil fuel companies knew about global warming and when, and what they did to deny, delay and deceive the public, the jury will not let the fossil fuel companies get away with their reckless misconduct," Worthington said.

Defendants say a court case won't help

Exxon says the lawsuit is unproductive.

"Suits like these continue to waste time, resources and do nothing to address climate change," a spokesperson for Exxon told CNBC. "This action has no impact on our intention to invest billions of dollars to leading the way in a thoughtful energy transition that takes the world to net zero carbon emissions."

The American Petroleum Institute, an industry trade group for the oil and gas industry, defended its constituents' work making energy available to consumers and, like Exxon, called the lawsuit unproductive.

"The record of the past two decades demonstrates that the industry has achieved its goal of providing affordable, reliable American energy to U.S. consumers while substantially reducing emissions and our environmental footprint," Ryan Meyers, senior vice president and general counsel for API, told CNBC in a statement. "This ongoing, coordinated campaign to wage meritless lawsuits against our industry is nothing more than a distraction from important issues and an enormous waste of taxpayer resources. Climate policy is for Congress to debate and decide, not the court system."

Legal counsel for Chevron called the lawsuit unproductive and unconstitutional.

"Addressing the challenge of global climate change requires a coordinated policy response. These lawsuits are counterproductive distractions from advancing international policy solutions," Theodore Boutrous, Jr. of Gibson, Dunn and Crutcher, told CNBC in a statement. "The federal Constitution bars these novel, baseless claims that target one industry and group of companies engaged in lawful activity that provides tremendous benefits to society."

Shell said it is working toward a low-carbon future and does not see a lawsuit as productive.

"The Shell Group's position on climate change has been a matter of public record for decades. We agree that action is needed now on climate change, and we fully support the need for society to transition to a lower-carbon future. As we supply vital energy the world needs today, we continue to reduce our emissions and help customers reduce theirs," a Shell spokesperson told CNBC.

"Addressing climate change requires a collaborative, society-wide approach. 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," Shell said.

ConocoPhillips and the Western States Petroleum Association told CNBC they don't comment on active litigation.

BP, Motiva, Occidental Petroleum, Space Age Fuel, Valero Energy, Total Specialties USA, Marathon Petroleum, Peabody Energy, the Koch Industries, and McKinsey did not immediately respond to requests for comment.