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Warming Responsible for Two-Thirds of Emissions from Western Wildfires

Warming is fueling ever larger wildfires in the U.S. West, which are becoming a major source of pollution. A new study finds that warming is to blame for nearly half of particulate pollution and two-thirds of emissions unleashed by western wildfires.

Warming is giving rise to bigger and more frequent fires by fueling hotter, drier weather and more intense droughts. In parts of the U.S., fires are up to four times as large, and strike three times as often as they did before the turn of this century.

Bigger fires are producing huge volumes of smoke. In the summer of 2020, a particularly brutal fire year, wildfires were the leading source of particulate pollution in the West, while in California, fires that year produced more carbon emissions than every power plant in the state put together.

The new modeling study shows warming played a bigger role in western forests and shrublands than in California wildlands nearer to cities, where humans have long had a role in igniting fires. Looking at the quantity of smoke produced by fires in different regions, and the varying effects of warming in those places, scientists determined how warming shaped emissions.

The study found that between 1997 and 2020, warming was responsible for 65 percent of carbon emissions and 49 percent of particulates originating from western wildfires. The findings were published in the Proceedings of the National Academy of Sciences.

Said lead author Loretta Mickley, of Harvard University, “Our hope is that this work will spur efforts to think more deeply about how we manage land and wildfires in the western U.S.”