Fire season in Colorado is typically during the hot, dry months of summer and early fall, with blazes most often occurring in the forested wilderness. But on Dec. 30, 2021, 100-mile-an-hour winds drove a massive firestorm into Boulder’s suburban neighborhoods from nearby grasslands, destroying close to a thousand homes.
Some 30,000 people had just minutes to evacuate.
“It's been an exhausting and scary couple of days for us in Boulder and Louisville and Superior,” says fire expert Jennifer Balch, who lives in Boulder County and directs the Earth Lab at the University of Colorado Boulder.
“I have friends [and] colleagues who lost their homes. Being a fire scientist, it's one thing to study it, but it's another thing to be living through it, and this event started just a couple miles from my home," Balch says. "I know that it could have been could have been my home, it could have been my neighborhood. We're living with the reality of being in the wild land urban interface, where homes mingle with flammable vegetation.”
Balch and her colleagues have mapped the perimeter, or outer limits, of all the wildfires that have happened in the US over the past two decades. Within those burned areas, she says, one million homes were touched in some way. Another 59 million homes were within about a half mile of the perimeter.
“I think we just haven't been acknowledging the high level of risk that we're living with today. And that risk is made worse by climate change — and that's a big part of the story, as well.”
“I think we just haven't been acknowledging the high level of risk that we're living with today,” she says. “And that risk is made worse by climate change —and that's a big part of the story, as well.”
Colorado, like other states prone to wildfire, is a beautiful, but also highly flammable state, Balch notes. Because Colorado is a beautiful landscape, a lot of people want to live there, and housing developments continue to expand into flammable areas without considering the risk.
“I think there's a lot of room for us to do it better — to build better and to build more fire-resilient homes and neighborhoods into our flammable, but beautiful, landscapes,” Balch says.
Climate change is a “huge factor” in the proliferation of wildfires throughout the western US, Balch says.
“The fact that I'm even talking…about winter wildfires is somewhat remarkable."
“The fact that I'm even talking…about winter wildfires is somewhat remarkable,” she points out. “There's only been one other time in my career where I've talked about snow putting out wildfires — that’s this year and last year. So what we're seeing is consistent with a trend in warming that we know is influencing wildfires and making them more frequent and making them bigger.”
“When this event started on Dec. 30, we had the warmest June through December period on record for the Front Range, going back to the 1960s,” Balch adds. “So what that did was it essentially made our fuels very dry and crispy and essentially ready to ignite. So [warming] was a huge factor that played into what happened.”
“We know that it takes just a little bit of warming to lead to a lot more burning. We've seen a doubling of the forests that have burned across the West since the 1980s.”
“We've seen a 2 degree Fahrenheit increase across the west over the last century,” Balch continues. “We know that it takes just a little bit of warming to lead to a lot more burning. We've seen a doubling of the forests that have burned across the West since the 1980s.”
More frequent wildfires and their increasing size and ferocity may add to the climate disruption that is making these fires more common and more fierce in the first place, particularly if changes to vegetation occur, Balch warns. If forest systems turn into grassland systems due to fire, for example, the Earth will lose the carbon storage capacity of those forests.
Scientists are seeing some early signs of this transition across the West, where some forests are not recovering or regenerating because the seedling trees that come in after a fire are not surviving from year to year in the drought conditions the region is experiencing.
Colorado is still in the midst of a megadrought, despite the snowfall that helped put out the Marshall fire. (The fire was named for its proximity to the unincorporated community of Marshall, near Boulder).
“It’s essentially more than a 20-year period where we've had a lack of moisture contributing to it being very hard for plants to survive, particularly ones that need a little bit more water, like trees,” Balch says.
One important lesson from the Marshall fire is that the wild land urban interface, where homes are most at risk, is “way bigger than we thought it was,” Balch says. She estimates that 13 million Americans live with high wildfire risk, and many of them likely don't know it.
Related: After wildfires, health risks linger
“We need to help communities prepare and recover from these types of events,” Balch says. “There are important factors that play into whether a community is ready: whether it's a low-income community, whether it has resources to do the fuel mitigation around neighborhoods and around homes.
“Age makes a difference. Elderly communities, who may not be as mobile or have as many resources, are also vulnerable and need greater assistance in times of evacuation. We also need to be concerned about those with preexisting health conditions, like asthma, that make them vulnerable to smoke and smoke exposures.
“So there's a lot that we need to be working on and thinking about and helping communities and those whose lungs are in the way and whose homes are in the way. We need to better protect people.”