Wildfires can be extremely destructive and deadly, but some types of fire are more dangerous than others.
“Fast fires”, which are defined as blazes that grow by at least six square miles in a single day are the most hazardous form of wildfire, causing more damage than most other fires.
NASA images, captured by the MODIS (Moderate Resolution Imaging Spectroradiometer) sensors on the Aqua and Terra satellites, reveal how much ground a fast fire can cover in a single day, showing the growing borders of the Northwest Oklahoma Complex fires in March 2017, which were started by striking lightning.
Between March 6 and March 7, these blazes—including the Starbuck, 283, Selman and Beaver fires—grew by up to 827 square miles in a single day.
Drag slider
compare photos
The prairie had been prime for burning after a dry spell and powerful winds spread the flames, with the fire complex eventually growing to cover an area nearly as large as Rhode Island, killing 4,000 cattle and 8 people, and destroying 151 structures.
According to a paper in the journal Science, between 2001 and 2020, fast fires made up only three percent of all wildfires across the U.S., but were responsible for 89 percent of all fire damage.
Fast fires were also found to be 66 percent of all fire deaths, 78 percent of structures destroyed and $18.9 billion in suppression costs.
This means that fast fires are a lot more dangerous than many large “megafires.”
“We’ve been focused on the wrong metric,” study co-author Jennifer Balch, director of the Environmental Data Science Innovation & Inclusion Lab at the University of Colorado Boulder, said in a statement. “It’s fire speed that really matters.”
Fast fires are usually driven by powerful winds, and often occur in grasslands in the fall when the vegetation is especially dried out. Strong winds can carry embers far ahead of the main fire—causing new ignitions—and also fan flames, increasing their intensity.
National Weather Service
Fast fires can cover large areas in a short amount of time, making them particularly dangerous and challenging to control.
“When you have extreme wind events, fires can become uncontrollable,” Michael Falkowski, manager of NASA’s wildland fire program, said in a statement. “For safety reasons, firefighters have to get out of the way.”
The 2020 Labor Day fires in Oregon and Washington scorched as much land in two weeks as had been burned in the past 50 years.
According to the Science paper, fast fires appear to be getting faster, with California blazes growing 398 percent faster in 2020 than they did in 2001.
“Nearly 3 million structures were within 4 kilometers of a fast fire during this period across the US,” the researchers wrote in the paper.
This increase in fire speed may be due to climate change causing higher temperatures, stronger winds and dryer vegetation, and/or may be a result of more people living near grasslands and accidentally starting fires.
“We expect to see more fast fires in the future,” said Balch.
“Devastating and fast-moving fires, such as the Camp fire in California and Lahaina fire in Hawaii, show how critical it is to plan for them.”
Do you have a tip on a science story that Newsweek should be covering? Do you have a question about fires? Let us know via science@newsweek.com.
References
Balch, J. K., Iglesias, V., Mahood, A. L., Cook, M. C., Amaral, C., DeCastro, A., Leyk, S., McIntosh, T. L., Nagy, R. C., St Denis, L., Tuff, T., Verleye, E., Williams, A. P., & Kolden, C. A. (2024). The fastest-growing and most destructive fires in the US (2001 to 2020). Science, 386(6720), 425–431.