Anthropogenic climate change contributes to wildfire particulate matter and related mortality in the United States

Beverly E. Law, J.T. Abatzoglou, C.R. Schwalm, D. Byrne, N. Fann, N. Nassikas

Wildfires have increased in frequency and intensity due to climate change and now contribute to nearly half of annual average of fine particulate matter in the US. Increasing temperatures due to climate change suggest a continuation of the increase in frequency, duration, and intensity of extreme events like wildfires and wildfire smoke. Such extreme events impact human health, safety, and welfare.

The goal of this study was to determine the contribution of anthropogenic climate change to wildfire smoke PM2.5 mortality on a county-level across the continental United States from 2006 through 2020.

Climate change contributed to 15,000 wildfire particulate matter deaths in the continental United States from 2006 through 2020, with a cumulative economic burden of $160 billion, according to observation-based modelling of climate, wildfire particulate matter, health, and economic impacts.

The ten counties with the highest annual mortality rates from climate change-related wildfire PM2.5 were all in the Western United States, dominated by California and Oregon. The 10 most impacted counties had climate change related mortality rates that were on par with the second most leading cause of mortality, cancer (malignant neoplasms).

Forest burn area significantly increased by 62% during the 15 years in the region. The largest amount of wildfire burn area occurred in 2020, which was a record hot, dry year for the west coast states. About 34% of the additional deaths attributed to climate change occurred in 2020, costing $58 billion. The economic burden associated with mortality from wildfire smoke particulate matter was highest in the west coast states - California, Oregon, and Washington.

This highlights the substantial impacts on nature that result in human deaths from failure to reduce greenhouse gas emissions. In a scenario without climate change contributing to wildfire smoke PM2.5, tens of thousands of deaths could be avoided and billions of dollars saved every year.