Scale Of Recent US Western Wildfires Enough To Alter CO Cycle In Earth's Atmosphere [View all]

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“Our research contributes to the growing body of research that shows that fires – in particular Pacific north-west region fires – are becoming more important for North American air quality” said Dr Rebecca Buchholz, a project scientist at National Center for Atmospheric Research. Looking at carbon monoxide, a trace gas emitted during fires, researchers analyzed the impact on atmospheric chemistry from 2002 to 2018, Buchholz explained. Though the scientists relied on carbon monoxide data to guide them, the contaminant also provided a framework to understand how other sources of pollution might be tied to the flames.

Her team, which also included scientists from across the country and around the globe, found that the dangerous pollutant peaks in August when fires are typically raging in the region, but dips during other months. The deviation from the annual cycle, she said, “is telling us that fires are compromising the ability of the atmosphere to self-clean”. Globally, carbon monoxide concentrations receded by half a percentage point a year over the 16-year study period. But across North America, the scientists found that August was an outlier. Carbon monoxide levels in the atmosphere follow a seasonal flow, driven to ebb and increase through a photochemical process. Prior to 2011, the regions fell in line with this pattern and levels of the pollutants peaked in the spring and waned in late summer. In a more recent period the researchers analyzed, from 2012-2018, a new trend began to emerge.

In August – when CO was expected to be driven to its lowest points – there were instead spikes. The scientists found that this not only affects atmospheric carbon monoxide, but was found closer to the Earth’s surface as well. The deviation from the worldwide trend was strongest in the Pacific north-west, where wildfire risks are high during that month, but the effect lingered in data collected in areas across the country and into the north-east of the North American continent.

The study’s findings were supported by four different global fire emission inventories, which consistently showed carbon monoxide fire emissions peaked in the Pacific north-west in August. Data from two other inventories that catalog emissions from human activity show carbon monoxide was not increasing in the region during the study period, helping the researchers rule out other causes of the August surge and its spread.

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https://www.theguardian.com/us-news/2022/apr/18/wildfire-smoke-emissions-study-pacific-north-west