Wildfire season is shifting, but its new time windows vary across Canada and the US drought-prone West
Climate change is altering North America’s wildfire season, but the direction of the change depends on the regional ecosystem, a new study finds.
The fire season in the boreal forests of northern Alaska and Canada has advanced on average; the prairie regions saw little change; and the fire season in the arid West and California extended into late fall and winter. The results were published on February 24 in the journal Geophysical research letters.
Article continues below
Zhang and his colleagues used data on burned areas in North America from 2001 to 2020, from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on NASA’s Aqua and Terra satellites. They also collected data on weather variables, vegetation, lightning potential and other environmental factors at the time of the fires.
They found that the boreal forest, or taiga, of Canada, Alaska and the Great Lakes region experiences earlier fires. This is due to earlier snowmelt, and therefore earlier fuel drying. Canada has experienced its worst wildfire season in 2023 and its second worst just two years later.
California’s hot desert southwest and Mediterranean climate region have seen a lengthening fire season, with more fires occurring after the traditional high-risk window.
Grasslands and grasslands experienced slight changes in fire season intensity and minimal change in seasonal timing. The Appalachians and Southeastern forests also saw little seasonal change.
The researchers also modeled future scenarios. In a high emissions environment climate change In this scenario, they found, the fire season in boreal forests will advance by about a week, while California’s annual fire season could extend more than a month later than the current June to October window. The desert southwest could experience a similar extension of the fire season, the researchers wrote.
This model will be useful for more detailed study, Zhang said. He and his team plan to use it to study the impacts of other factors, such as vegetation change and human activities. (According to the National Park Service, 85% of forest fires in the United States are caused by human actions, such as arson or a failure to properly extinguish a campfire.) The model is also useful for predicting pollution and carbon emissions from these fires, Zhang said.
“This model is really good at predicting wildfires,” he said. “So now we want to predict wildfire emissions into the atmosphere.”
