Nighttime Intensity Of Fires Growing Rapidly In American West In Tandem W. Continuing Warming
When the Cameron Peak Fire ignited in northern Colorado in August 2020, few could foresee its longevity. As it burned, summer turned into winter. Nearly a semester of school passed. By the time the fire was fully contained in December, it had become the state’s largest on record. In recent decades, fires have become more intense and longer lasting amid rising temperatures linked to human-caused climate change. A key influence on their growing duration? Their increasing ability to survive the night, when temperatures typically dip and humidity rises.
A study published Wednesday in Nature shows that a trend toward warmer and drier conditions after sundown is helping blazes withstand what should be unfavorable conditions — making fire containment more difficult for responders. Crews are less able to rely on relief in fire intensity previously offered by nighttime cooling. “The fact that the [Cameron Peak] fire was burning for months, to me is an indication that we were essentially able to pass through the night,” said Jennifer Balch, the director of Earth Lab at the University of Colorado at Boulder. “We were able to burn from day to night, from day to night, and that fire burned over 200,000 acres.”
Cameron Peak isn’t the only notable example of nighttime fire growth. During Australia’s 2019-2020 bush fire season, fires seemed to spread more rapidly at night than during the day for the Snowy Complex Fire in the southeast of the country. In fact, about three-quarters of satellite fire detections occurred at night. In 2017, the Tubbs Fire in Northern California burned across 36,000 acres and became the most destructive fire in the state at that time. Satellite data showed more than half of the fire detections occurred at night.
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The increase in nighttime fire activity was not necessarily surprising, said co-author John Abatzoglou at University of California Merced, but “the magnitude of the change was noteworthy” in certain regions. For example, the U.S. West stood out against the global average. Nighttime fire intensity from 2003 to 2020 increased by 28 percent in the region. The West also experiences around 11 more flammable nights compared to four decades ago. Grasslands and savannas in South America, Africa and Asia and open shrub lands in Australia also saw an increase in the number of flammable nighttime hours.
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https://www.washingtonpost.com/weather/2022/02/16/fire-intensity-night-study/
