In a groundbreaking lawsuit filed in Washington state, a woman is taking on some of the world’s largest oil companies, alleging that their role in accelerating climate change led directly to her mother’s death during the record-shattering heat wave that gripped the Pacific Northwest in June 2021.

Misti Leon, the plaintiff, has brought a wrongful death case against Exxon Mobil, Chevron, Shell, BP, ConocoPhillips, Phillips 66, and Olympic Pipeline Co. She alleges that the fossil fuel companies are liable for the death of her mother, 65-year-old Juliana Leon, who died amid the intense temperatures of the so-called “heat dome” that caused hundreds of fatalities in the region.

Leon’s suit is the first of its kind to explicitly argue that corporate actions related to climate change directly caused an individual’s death. It claims that the defendant companies knowingly contributed to global warming by producing and promoting fossil fuels while misleading the public about the risks associated with their emissions. The lawsuit accuses the companies of wrongful death, public nuisance, and failure to warn, potentially opening a new frontier in climate-related litigation.

“I never would have in a million years guessed that a heat dome and climate change would be what killed my mother and what took her from me,” Misti Leon said in a statement.

The 2021 heat dome was one of the deadliest climate-related disasters in U.S. history. Temperatures soared to unprecedented levels, overwhelming infrastructure and causing a surge in heat-related illnesses and deaths. In Oregon and Washington alone, nearly 600 people are believed to have died due to the extreme heat. Elderly individuals, people without access to air conditioning, and those living in poorly ventilated housing were among the most vulnerable.

Juliana Leon, according to her daughter, had no access to air conditioning and succumbed to heatstroke in her home during the crisis. Misti Leon’s legal team is arguing that her mother’s death was not simply the result of a freak weather event, but a foreseeable outcome of decades of fossil fuel production and climate disinformation.

The case may mark a turning point in how courts and the public perceive corporate responsibility in the climate crisis. While dozens of lawsuits have been filed by cities, states, and municipalities seeking to hold oil companies accountable for environmental damages and adaptation costs, this is the first known suit filed by a private individual tying a personal loss to corporate emissions.

Legal experts are closely watching the case, as it could set a precedent for future wrongful death or injury claims related to climate change. “This could be the beginning of a wave of litigation connecting personal harm to corporate contributions to climate change,” said Michael Gerrard, director of the Sabin Center for Climate Change Law at Columbia University.

The scientific consensus is clear: human-caused climate change, driven primarily by the burning of fossil fuels, is making extreme weather events more frequent and severe. Heat waves are now considered among the deadliest forms of natural disasters in the United States, and their toll is expected to increase as the planet warms.

Public health officials have warned that unless drastic action is taken to reduce emissions and adapt infrastructure, heat-related deaths will continue to climb—especially among the elderly, people with preexisting health conditions, outdoor laborers, and low-income households.

For Misti Leon, the lawsuit is not just about seeking justice for her mother, but about raising awareness of the human cost of inaction and corporate malfeasance. “I want people to understand that climate change isn’t just about polar bears or rising sea levels. It’s about our parents, our neighbors, and our communities,” she said.

As the case moves forward, it may force courts to confront a powerful and urgent question: can fossil fuel companies be held directly accountable for the lethal consequences of a warming world?