This summer, millions of Americans have sweat through record-breaking heat waves. Tragically, not all of them have survived the ordeal. Dozens of communities have already recorded deaths from these latest rounds of extreme heat; hundreds more people could lose their lives before summer ends.
If someone were to push a “killer heat” button, law enforcement would make stopping them a top priority. We have not treated lethal, climate-induced heat as that sort of public safety threat because we see heat waves as natural disasters.
But many of the extreme heat waves we’ve seen in recent years are not natural—they are environmental disasters that in some cases would have been “virtually impossible” but for human-caused climate change. These catastrophes are happening in large part because of the actions of a small number of oil and gas companies. Those companies have generated a substantial portion of the greenhouse gas emissions that have caused the planet to heat up, while simultaneously deceiving the public about the dangers of those emissions.
From this perspective, deaths from climate-related extreme heat start to look less like tragic accidents and more like crimes. But could there really be enough evidence to credibly charge Big Oil with homicide for causing lethal heat waves? To answer that question, we carefully assessed the available evidence and concluded that a formal investigation, built on top of already-public evidence, could give prosecutors what they need to convict the corporate perpetrators and bring justice to the victims of extreme, unnatural heat.
Any real prosecution would turn on hard facts, so we focused our analysis on a specific real-world scenario: the lethal heat wave that struck the American Southwest in July 2023. That event caused a massive loss of life, including hundreds of deaths in Maricopa County, Arizona.
Arizona’s reckless manslaughter and second-degree murder laws punish causing death through conduct that is reckless or that manifests “extreme indifference to human life.” Voluminous evidence already shows that oil companies were aware that producing and selling fossil fuels would contribute to, in their own words, “globally catastrophic” climate harms that would “submerge New York,” do “great irreversible harm to our planet,” “have serious consequences for man’s comfort and survival,” and cause “suffering and death due to thermal extremes.” Fossil fuel companies even raised the height of offshore drilling platforms to account for expected sea-level rise. Demonstrating criminal recklessness based on that knowledge—plus the additional evidence a formal investigation would likely turn up—seems eminently feasible.
Causation—i.e., showing that Big Oil’s actions in fact caused victims’ deaths—is admittedly complex. Still, it’s important to remember that in Arizona and elsewhere, a defendant cannot “avoid liability for [a] causative act by claiming that the conduct of some other person was also a contributing cause.” Federal prosecutors regularly grapple with a similar, perhaps even harder to prove causation standard when charging drug dealers with having sold the drugs that later caused a user’s death. With Arizona’s standard in mind, we believe that it would be possible to prove each link in the causal chain between Big Oil and a given climate-related death.
Link 1: The Maricopa County Department of Public Health recorded hundreds of deaths in July 2023 as “heat caused,” meaning that environmental heat was the direct cause of death, not just a contributing factor.
Link 2: Climate-attribution studies found that the occurrence of such heat in Phoenix would have been “virtually impossible” but for human-caused climate change.
Link 3: A small number of fossil fuel companies are responsible for a large portion of all the human-generated greenhouse gas emissions. These companies also actively spread climate disinformation, which for years enabled them to continue to emit the carbon at the core of their businesses.
Putting the links together, we feel that a prosecutor could build a case that would reasonably convince a grand jury and ultimately a trial jury that Big Oil recklessly caused many of the deaths during last July’s heat wave. And the evidence of their emissions and climate deceptions would only grow stronger with a formal investigation.
Of course, the fossil fuel industry would respond to a prosecution with all the legal firepower at its disposal, so we also assessed a range of likely defense arguments. For example, companies might try to break the causal chain by blaming regular people’s consumption—their driving habits, air-conditioning use, etc. But to shield an actor from liability, an intervening cause must have been unforeseeable. Big Oil not only clearly foresaw that its products would be used precisely as intended; it also extended our carbon-burning habits by forestalling safer energy alternatives through deceptive disinformation campaigns.
Big Oil might also assert a necessity defense, arguing that shifting away from fossil fuels would have imperiled the greater good. But a necessity defense requires an imminent threat and an absence of legal alternatives. Although an overnight shutdown of all fossil fuel production would be very damaging, this was never an imminent threat. The only “threats” that fossil fuel companies sought to avoid were lower profits and a gradual transition to clean energy sources.
The oil companies’ lawyers might also argue that it would be unfair to prosecute them because producing and selling fossil fuels is legal. But the act behind reckless manslaughter or second-degree murder is often otherwise legal: Driving, for example, is authorized, subsidized, and regulated. And yet driving in a manner that recklessly causes death is still a crime. Similarly, recklessly generating planet-heating emissions at a scale that causes death should be a crime.
Fossil fuel companies will probably frame any prosecution as a conspiracy to use the criminal justice system to further political goals. But pursuing justice for victims and their bereaved families is the fundamental function of a prosecutor. In a courtroom, facts beat spin, and the facts look clear: Victims are dead; they were killed in a heat wave that was made possible by climate change; and fossil fuel companies knowingly caused climate change.
These climate disasters didn’t come out of nowhere. Arizona’s heat wave—like other climate catastrophes, including the extreme heat baking millions of Americans this summer—was caused by particular actors that chose to maximize profits even if doing so meant inflicting suffering and death. Although recent Supreme Court decisions may hinder any effective regulatory solution to this ongoing climate threat, using criminal law as an alternative means for holding these actors accountable could vindicate past wrongs and encourage better future behavior.
Regular people are paying the ultimate price for those decisions. These victims deserve justice no less than do victims of street-level homicide. Piecing together a criminal case will take immense work, but our analysis shows that prosecutors may have a path to secure that justice if they choose to pursue it.