(CN) — The amount of fire activity in the Sierra Nevada region may be on track to considerably increase, according to new research on the effects of the hottest summer days on fire risk.
In an article published Wednesday in the journal Science Advances, researchers predicted the ramifications associated with hotter summer days increasing in frequency. They estimate the number of fires in the Sierra Nevada could increase by at least 19% and as much as 83% by the 2040s.
“With ongoing climate change, we're going to see an increase in the risk of fires because of the fact that you're having a warmer climate leading to warmer days,” said Aurora Gutierrez, the lead author of the study and a project specialist in the Department of Earth System Science at University of California, Irvine.
Gutierrez and her colleagues tracked the impact of daily temperatures on fire activity from 2001 to 2020 using satellite imagery data on meteorological conditions, fire occurrence and the amount of area burned daily. They found a strong relationship between daily temperatures and the likelihood of wildfires.
Not only will temperature increases likely spur an increased number of fires, but the study indicates that the amount of area burned could increase by at least 26% and as much as 92%.
“When there's hot days, you tend to have a lot of drying of fuels or vegetation in that region. When there's a possible ignition or spark that ignites a fire, because it's such a hot day, these fires spread so rapidly, leading to really large mega-fires that have very big consequences in this region,” said Gutierrez.
Gutierrez pointed out that the heavily forested Sierra Nevada region, which spans a long strip of central and eastern California and extends into western Nevada, provides significant fuel for wildfires. The 2021 wildfire season proved devastating for the area, which is typically a haven for tourists and locals seeking outdoor recreation at the alpine lakes and famed ski resorts. The Dixie and Caldor fires together blackened over a million acres, destroyed over 2,000 structures and forced thousands to evacuate their homes.
Over the course of the research, Gutierrez said the destructive magnitude of recent fire seasons mirrored their findings in notable ways. She said her initial research analyzed the fire seasons spanning 2001 to 2018. When she added the 2019 and 2020 fire seasons, she said all her models had to be redone.
“The 2020 fire season was off the charts. The amount of burned area that occurred during that season was just crazy for the overall time series of burned area,” Gutierrez said. She noted that the 2020 fire seasons was marked by “optimal conditions” for wildfires, including multiple heat waves, which led to dry, flammable fuel that can defy even the most aggressive fire suppression tactics.
“It was kind of cool and kind of scary to see that one year can really do that much damage to the whole time series of burned area,” Gutierrez said.
She added that increasingly frequent large-scale fires like Dixie and Caldor can contribute to a vicious cycle of escalating temperatures that lead to more extreme wildfires and other climate events.
“Once these fire burn, you’re getting increases of greenhouse gases and aerosols into our atmospheres, just amplifying the cycle all over again," she said. "The risk is just going to increase well into the future.”
Going forward, Gutierrez said she is interested in seeing analyses of other regions in California to evaluate the different trends on how the fires in those regions will be impacted by rising temperatures. She said that it would be interesting for scientists to try to quantify how other factors, like soil moisture or the density of the human population in a region, influence the ignition of fires.
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