Western Wildfires Are Fueling Extreme Weather in Other States, Federal Scientists Say

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Destroyed property is left in its wake as the Oak Fire chews through the forest near Midpines, northeast of Mariposa, California, on July 23, 2022. Credit: David McNew/AFP via Getty Images
Destroyed property is left in its wake as the Oak Fire chews through the forest near Midpines, northeast of Mariposa, California, on July 23, 2022. Credit: David McNew/AFP via Getty Images

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Scientists are once again sounding the alarm over the intensifying wildfires plaguing the American West. In a series of new peer-reviewed studies, researchers warned that the behemoth blazes of recent years have contributed to a surge in harmful air pollution and planet-warming greenhouse gas emissions, and are even influencing extreme weather in other regions of the country.

In late September, Stanford University researchers published a study that found residents of Western states were exposed to a 27-fold increase of harmful particulate matter pollution, known as PM2.5, between 2006 and 2020 as wildfires intensified. Then this month, researchers from the University of Chicago and the University of California, Los Angeles, concluded in their own study that the wildfires of 2020 contributed to roughly a third of California’s total greenhouse gas emissions that year. And on Monday, the Department of Energy released groundbreaking research that found Western blazes are increasing the intensity of extreme weather in states as far east as Nebraska.

While it’s well known that particularly hot fires can spawn their own weather, Monday’s study was the first to link Western conflagrations to extreme weather events occurring in other parts of the country, including instances of damaging hail and deadly flash floods.

“Western wildfires significantly increase the intensity of severe storms over the central United States,” Jiwen Fan, an earth scientist with the energy department and a co-author of the agency’s study, told The Guardian. “This is the first study where we are really showing that wildfires can have a significant impact on the downstream weather.”

The studies add to a quickly growing body of evidence that suggests that the risks associated with wildfires aren’t just getting worse in the West, but expanding into areas far from where the blazes burn.

Recent research has shown wildfire smoke from California and Colorado was able to travel for thousands of miles to other states where it increased the risk of asthma attacks, lung disease and other health conditions. In one extreme case, smoke from Western conflagrations made it all the way to New York City. Western megafires have also been linked to weakening the Earth’s protective ozone layer and contributing to a viscous climate cycle, with more fires leading to faster snowmelt and increased aridity, which, in turn, makes forests more flammable. 

As for Monday’s study, energy department researchers analyzed and compared weather and wildfire data from 2009 to 2018, finding that Western fires boosted the rates of heavy precipitation and significant severe hail in the central U.S. by 38 percent and 34 percent, respectively. The researchers define significant severe hail as being at least 2 inches in diameter—larger than the size of a golf ball.

Both heat and aerosols from wildfires play an important role in those trends, the study said, by influencing the conditions that help create powerful storms—namely surface temperature, air pressure, windshear and atmospheric moisture.

Still, in many ways, the most significant impacts from wildfires remain in the West, where ongoing blazes continue to ravage states from the Pacific Coast to the eastern edge of the Rocky Mountains.

Last month’s Stanford study, for example, found that the number of people exposed to dangerous levels of PM2.5 pollution in the West has ballooned over the course of about a decade. In 2006, less than half a million people were believed to live in areas experiencing dangerous levels of wildfire-related PM2.5 concentrations, the study said. By 2020, that number skyrocketed to more than 8 million.

Research has linked PM2.5 to increased risk of asthma, lung and heart diseases, as well as premature death. Scientists estimate that 50,000 deaths every year in the U.S. are caused in part to PM2.5 exposure. People of color and low-income households are also disproportionately exposed to such pollution—a finding the Stanford study reaffirmed by showing that predominantly Hispanic communities were most impacted by Western blazes.

And this month’s research from the University of Chicago and UCLA found that the greenhouse gas emissions from California wildfires in 2020 alone equaled twice the amount of emissions the state was able to reduce over the course of 16 years. In fact, the study said that wildfires were the second largest source of climate-warming emissions in 2020 for the Golden State, behind only the transportation sector, releasing roughly 127 million metric tons of carbon dioxide equivalent into the atmosphere. By comparison, the state reduced its greenhouse gas emissions by just 65 million metric tons between 2003 and 2019.

“Essentially, the positive impact of all that hard work over almost two decades is at risk of being swept aside by the smoke produced in a single year of record-breaking wildfires,” Michael Jerrett,  an environmental health sciences professor at UCLA and a co-author of the study, said in a press release. 

Jerrett’s study also examined the financial costs of wildfires, finding that the carbon emissions released from the 2020 wildfires equated to more than $7 billion in total global damages, about $987 million in damages to the United States and nearly $99 million in damages for California. These damages were calculated using the Biden administration’s “social cost of carbon” equation, the authors said, and don’t include the fire control costs, damages from air pollution and direct loss of life and property.

Scientists worry such financial, environmental and health-related consequences will only get worse in the coming years, as the climate crisis continues to exacerbate drought and other conditions that fuel the region’s destructive blazes. Cooler autumn temperatures typically provide some relief to Northwest states dealing with fires. But amid yet another record-shattering heat wave in the region, officials are warning residents to not let down their guard—and for good reason.

Over the weekend, the Nakia Creek Fire on the southern border of Washington state exploded in size to more than 1,560 acres, forcing thousands of people from their homes and putting tens of thousands more on notice to evacuate if conditions worsen. It’s just one of 72 large fires currently burning across the American West.

“It may be October, but it’s clear we’re not out of the woods when it comes to wildfire smoke and the dangers it can bring,” Kaitlyn Kelly, an air quality expert with the Washington Department of Health, said in a statement, noting that extended exposure to “lower levels” of smoke can still be dangerous. “Don’t wait until you start feeling symptoms to act.”

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