Limiting Global Warming to 2°C Could Prevent Tens of Thousands of U.S. Wildfire Deaths Annually

When smoke from an active wildfire spreads hundreds of miles into cities, it has a unique quality. It’s a gray-orange haze that creeps in silently, dimming the afternoon light and giving the air a slightly acrid edge instead of the thick, choking haze you might anticipate. Over the past few summers, people in Denver, Chicago, and New York City have learned to recognize it: the faint sting at the back of the throat, the smell of something burning far away, and the air quality alerts on their phones telling them to stay inside. In a way that no one had anticipated, it has become a part of the seasonal calendar. Additionally, a recent study from Stony Brook University is quantifying the effects of that haze on American bodies as well as the potential effects of varying degrees of climate action.
According to the study, which was published in the Proceedings of the National Academy of Sciences, wildfire smoke will be responsible for about 64,000 deaths in the US annually if global mean surface temperatures rise by 3 degrees Celsius above pre-industrial levels, which is roughly where current greenhouse gas trajectories are headed. Compared to the estimated death toll during the baseline period from 2011 to 2020, that number represents a 60% increase. In other words, as a short-term trend already detectable in the data, rather than as a far-off forecast. To arrive at these figures, the researchers generated over 700 potential future scenarios using 28 global climate models, which is about as rigorous a modeling effort as this type of research produces.
The analysis was developed by lead author Dr. Minghao Qiu, an assistant professor at Stony Brook’s School of Marine and Atmospheric Sciences, based on a question that is rarely asked: what is the current cost of climate change in American lives through this particular pathway? Sea level rise, heat stress, and agricultural disruption are the main topics of most estimates of the “social cost of carbon”—the economic harm caused by each ton of CO2 emitted. Since wildfire smoke is too erratic or too localized to accurately model, it has generally been excluded from those computations. According to Qiu’s paper, that is a significant omission. The domestic cost of carbon in the United States rises by 74% when smoke damages are included in current estimates. It’s not a rounding error. The metrics used by governments to assess climate policy have been fundamentally reframed.

This mechanism is more diffuse than most people realize, which makes it worthwhile to comprehend in some detail. PM2.5, or fine particulate matter, is carried by wildfire smoke and is small enough to evade the lungs’ natural defenses and enter the bloodstream directly. Once there, they put the cardiovascular system under stress, exacerbate pre-existing respiratory conditions, and increase the risk of heart attack and premature death. Older adults, children, pregnant women, and those who already have heart or lung disease are the most vulnerable. However, smoke events disregard those classifications because the particulates move. Unhealthy air from a fire in northern California or eastern Washington can spread over the Midwest and the Great Plains, affecting communities that have nothing to do with the ecology of western fires but whose citizens suffer for days at a time.
The Stony Brook study translates temperature targets directly into lives, which is what sets it apart from earlier research in this field. About 8,900 deaths would be avoided annually if global warming were limited to 2 degrees Celsius rather than 3. Every year, about 11,600 lives would be saved if temperatures were kept at 1.5 degrees. These are the people who would otherwise pass away in the year the policy goes into effect, the year after that, and each year after that. They are not abstract figures for future generations. The researchers estimated that the net present value of wildfire smoke mortality damages in the United States alone would be $11.20 for every additional ton of carbon dioxide emitted in 2025. The costs to other nations, property damage, and the burden on the healthcare system are not included in that figure. Just the monetized death toll in America.
Reading this research gives me the impression that climate policy has been priced at a discount for a long time, with regulatory decision-making models consistently underestimating the risks by omitting particular damage pathways like this one. This could be a contributing factor in the long-standing discrepancy between what governments actually do and what scientists claim is essential. When 64,000 smoke deaths occur annually at 3 degrees as opposed to 52,000 at 2 degrees and the lower number at 1.5 degrees, the argument for action takes on a different appearance. It shifts from discussing future generations to discussing who will be alive in 2045.
How soon this research will be incorporated into the policy evaluation tools used by organizations like the Office of Management and Budget and the EPA to establish environmental regulations is still unknown. However, Dr. Qiu’s paper specifically advocates for that integration, contending that rather than being viewed as a local issue for western states to handle independently, wildfires should be at the core of U.S. climate policy. After all, the smoke is not limited to the West. It has never done so.