US wildfire plumes are getting taller, with serious consequences

Smoke from blazes in the Western United States is rising higher, with pollutants spreading and impacting air quality over greater distances. 

According to new research conducted by the University of Utah, U.S. wildfires impacting states in the west of the country – where blazes are most ferocious due to a combination of high temperatures and dry conditions – are producing taller plumes of smoke, with serious consequences for the environment and public health. 

What this means is that aerosols and other pollutants in the smoke reach higher altitudes, where they are more easily dispersed over greater distances, impacting air quality across more areas than ever before. Those behind the investigation believe climate change itself may be the cause, as less precipitation and increasingly arid terrain is known to intensify wildfire activity. 

‘Should these trends persist into the future, it would suggest that enhanced Western U.S. wildfire activity will likely correspond to increasingly frequent degradation of air quality at local to continental scales,’ said Kai Wilmot, a postdoctoral researcher in the Department of Atmospheric Sciences at the University of Utah.

In order to reach these conclusions, Wilmot and colleagues Derek Mallia, Gannet Haller, and John Lin modelled activity around 4.6m plumes originating in the Western U.S. and Canada between 2003 and 2020. These were then divided into Environment Protection Agency (EPA) ‘ecoregions’, and trends in maximum height were measured for August and September each year. 

To use California’s Sierra Nevada as an example, plumes were found to have increased in height by an average of 750ft per year, while across all regions the average annual increase was 320ft. ‘Given climate-driven trends towards increasing atmospheric aridity, declining snowpack, hotter temperatures, etc., we’re seeing larger and more intense wildfires throughout the Western U.S.,’ said Wilmot. ‘And so this is giving us larger burn areas and more intense fires.’

The results back up an earlier study by the National Center for Atmospheric Research, which found wildfires in America’s Pacific Northwest are now so severe they substantially impact air pollution patterns across the whole of North America.