A groundbreaking study from the University of Colorado Boulder highlights the increasing threat of fast-growing wildfires in the Western U.S., urging improved hazard preparedness to protect communities from these rapidly advancing blazes.
Wildfires are spreading more rapidly and causing devastating damage in the Western United States, according to a new study led by the University of Colorado Boulder. These “fast fires,” which propel embers ahead of the main flames, were found responsible for nearly 90% of fire-related damage from 2001 to 2020, despite constituting a small fraction of the total fires.
The study highlights the critical importance of addressing fire speed, according to lead author Jennifer Balch, an associate professor of geography at UC Boulder and a CIRES fellow.
“We hear a lot about megafires because of their size, but if we want to protect our homes and communities, we really need to appreciate and prepare for how fast fires move. Speed matters more for keeping people safe,” she said in a news release.
Published in the journal Science, the study’s findings underscore a significant gap in current national fire risk assessments, which typically do not consider the speed at which fires spread, leaving communities unprepared for fast-growth fire events.
Balch and her team were motivated to delve deeper into the issue of fire speed following the Marshall Fire in December 2021, which obliterated over 1,000 homes in Boulder County, Colorado. Despite burning less than 6,100 acres, the fire’s rapid spread due to dry conditions and high winds highlighted the danger of fast-moving fires. This tragedy, which forced the evacuation of tens of thousands of residents, spurred the research team to investigate fire growth rates nationwide.
The researchers utilized satellite data to assess more than 60,000 fires across the contiguous United States from 2001 to 2020. A sophisticated algorithm enabled them to analyze fire perimeter data daily.
“Until now, we had scattered information about fire speed,” co-author Virginia Iglesias, an interim director of UC Boulder’s Earth Lab, said in the news release. “We harnessed Earth observations and remote sensing data to learn about fire growth across the nation in a systematic manner.”
Their analysis revealed a dramatic 250% increase in the average maximum growth rate of the fastest fires in the Western United States over the past two decades.
“Fires have gotten faster in the Western U.S. in just a couple of decades,” added Balch. “We need to focus on what we can do to prepare communities: hardening homes and making robust evacuation plans.”
To understand the impact of these fast fires on human settlement and infrastructure, the team compared the growth rates with data on structural damage from incident reports. They found that while these fast fires made up only 2.7% of those recorded, they were responsible for destroying 88% of the homes lost to wildfires over the studied period.
“These results change how we think about wildfire risk because they position growth rate as a key determinant of a fire’s destructive potential,” added Iglesias.
The researchers stress the need to incorporate fire growth rate measurements into national risk models used by government agencies and insurance companies. Current models consider factors such as the total area burned and fire intensity but overlook the crucial aspect of fire speed.
“When it comes to safeguarding infrastructure and orchestrating efficient evacuations, the speed of a fire’s growth is arguably more critical than its sheer size,” Iglesias added.
As wildfires in the Western United States continue to grow faster and more destructive, the study serves as a stark warning and a call to action for improving hazard preparedness to protect lives and property from these increasingly rapid threats.