Forest fires have crept higher up mountains over the past few decades, scorching areas previously too wet to burn, according to researchers from McGill University. As wildfires advance uphill, a staggering 11% of all Western U.S. forests are now at risk.
“Climate change and drought conditions in the West are drying out high-elevation forests, making them particularly susceptible to blazes,” says lead author Mohammad Reza Alizadeh, a Ph.D. student at McGill University under the supervision of Professor Jan Adamowski. “This creates new dangers for mountain communities, with impacts on downstream water supplies and the plants and wildlife that call these forests home.”
Climate warming has diminished ‘flammability barrier’
In a study published in Proceedings of the National Academy of Sciences, the researchers analyzed records of fires larger than 405 hectares in the mountainous regions of the contiguous Western U.S. between 1984 and 2017. Their results show that climate warming has diminished the ‘high-elevation flammability barrier’ – the point where forests historically were too wet to burn regularly because of the lingering presence of snow. The researchers found that fires advanced about 252 meters uphill in the Western mountains over those three decades.
The amount of land that burned increased across all elevations during that period, however the largest increase was at elevations above 2,500 meters. Additionally, the area burning above 8,200 feet more than tripled in 2001 to 2017 compared with 1984 to 2000. Over the past 34 years, rising temperatures have extended fire territory in the West to an additional 81,500 square kilometers of high-elevation forests, an area similar in size to South Carolina.
“Climate change continues to increase the risk of fire, and this trend will likely continue as the planet warms. More fire activity higher in the mountains is yet another warning of the dangers that lie ahead,” says co-author Jan Adamowski, a Professor in the Department of Bioresource Engineering at McGill University.
Mohammad Reza Alizadeh et al, Warming enabled upslope advance in western US forest fires, Proceedings of the National Academy of Sciences (2021). DOI: 10.1073/pnas.2009717118
Mountain fires burning higher at unprecedented rates (2021, June 17)
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