Wildfires exacerbated by climate change are responsible for thousands of deaths and significant economic costs annually in the United States, according to a recent study published in the journal Nature Communications Earth & Environment. Conducted by a team of researchers, the paper indicates that from 2006 to 2020, climate change contributed to approximately 15,000 deaths due to exposure to fine particulate matter (PM2.5) from wildfire smoke, amounting to an economic toll of about $160 billion. The annual death toll varied between 130 and 5,100, with the highest numbers reported in states like Oregon and California.
According to study author Nicholas Nassikas, a physician and professor at Harvard Medical School, the increase in wildfire smoke events prompted the research team to investigate the implications of a changing environment on mortality rates. This thorough examination of the long-term implications of PM2.5 exposure makes the study one of the first to isolate climate change’s direct effect on mortality linked to wildfires, as noted by Lisa Thompson, a professor at Emory University who studies air pollution and climate change.
The research specifically targets the health concerns associated with PM2.5, which can penetrate deep into the lungs, causing immediate discomfort such as coughing and itchy eyes. Long-term exposure exacerbates chronic conditions and leads to severe health issues, particularly among vulnerable populations, including children, pregnant individuals, the elderly, and outdoor workers. The Health Effects Institute has estimated that PM2.5 contributes to around 4 million deaths globally.
Emerging evidence suggests that PM2.5 derived from wildfire smoke may be more toxic than that from other pollution sources. When wildfires spread into urban areas, they can ignite burning vehicles and other toxic materials, increasing health risks. Numerous studies have linked anthropogenic climate change—primarily due to the combustion of coal, oil, and gas—to an increase in wildfire incidents in North America. Climate change is driving up drought conditions in the West and other extreme weather events. This results in drier ecosystems, which act as fuel for fires. The combination of hotter temperatures and parched vegetation has led to an uptick in wildfire frequency, severity, and the consequent smoke production.
Commenting on the study, Jacob Bendix, a geography and environment professor emeritus at Syracuse University, expressed dismay but indicated that the findings were not unexpected. He emphasized the significance of the reported figures and cautioned that people outside active wildfire zones often underestimate the far-reaching implications of increasing fires on public health and the economy.
The researchers employed a framework analyzing modeled and existing data to assess the study's conclusions. They estimated the impact of climate change on the area burned by wildfires by comparing actual climate conditions—such as temperature and rainfall—during fire incidents with hypothetical conditions devoid of climate change influences. Using this method, they estimated the PM2.5 levels from wildfire smoke attributed to climate change, leading to the conclusion that 10% of the 164,000 deaths linked to PM2.5 exposure from 2006 to 2020 had climate change as a contributing factor. Notably, mortality rates were 30% to 50% higher in some western states and counties.
However, the study faced scrutiny regarding its conclusions. Marshall Burke, a global environmental policy professor at Stanford University, acknowledged the solid evidence linking climate change to burned areas but noted the complexity of associating smoke levels with health impacts due to variables like wind direction. He raised questions about how the estimated fatalities compared to those tied to general air pollution.
Patrick Brown, a lecturer in climate and energy policy at Johns Hopkins University, expressed concerns about the study's approach, suggesting that while it recognized non-climate factors impacting wildfires, it did not adequately account for their importance. He cautioned that policymakers might erroneously conclude that reducing carbon emissions is the sole solution, neglecting other immediate fire mitigation strategies such as fuel management, prescribed burns, and public health initiatives.
Despite these concerns, Nassikas underscored the urgency of addressing the escalating mortality from wildfire smoke and the critical need for greenhouse gas emissions reduction to mitigate future health impacts. He highlighted the dual purpose of the study: raising awareness of the issue and prompting discussion about actionable interventions at various societal levels.
