Two people still remain missing and are presumed dead following the devastating firestorm that swept through the cities of Louisville and Superior, Colorado last Thursday. Search and rescue missions continue but have been hampered by the 10 inches of snow that fell Friday night and extinguished most of the flames.
The Marshall Fire is the most devastating in Colorado history, destroying over 1,000 homes and businesses and causing tens of thousands of people to flee their homes at a moment’s notice as the flames burned through over 6,000 acres of land (9.4 square miles). Devastation from the fire struck deep into the hearts of the suburban communities southeast of Boulder, leveling whole neighborhoods and large business centers, including a Target shopping mall, a Tesla car dealership, and a hotel.
Following the disaster, residents have been struggling to stay warm. According to Alice Jackson, president of Xcel Energy, 1,600 people are still without electricity and 11,600 without gas as of Sunday. Gas utilities must be turned on individually for safety reasons, meaning that it could take days to return heating to the homes that remain standing.
For those who lost their homes, bottled water and donated space heaters were handed out by the Salvation Army in the neighboring city of Lafayette and resources from the Federal Emergency Management Agency (FEMA) have been deployed to the area.
The cause of the fire is still under investigation, but officials have stated that they have narrowed the source of the ignition to a single neighborhood where a shed was photographed in flames by a passerby on Thursday. Search warrants have been issued, but few details have been released as the investigation continues. Officials had suggested early on that the cause of the fire could have been downed power lines, but have since confirmed that no power lines were down at the time the fire began to spread.
What made the Marshall Fire so destructive and astonishing was that the fire spread so quickly and so deep into a heavily populated area. Typical wildfires in Colorado occur further up in the foothills and in the mountains, often farther away from human settlement in what scientists call the Wildland-Urban Interface (WUI), the space where human development and wild land meet.
In previous decades the WUI was sparsely populated, making the threat of wildfires to human life relatively small. However, since the 1990s, suburban expansion in Colorado has continuously marched west and up into the fire-prone grasslands in the foothills of the Rocky Mountains. Both Louisville and Superior, around 20 miles northwest of Denver and just a few miles from Boulder, sit right next to areas that the Colorado State Forest Service considers to be of “Very High” risk for wildfires.
While much of the cities’ development sits beyond this risk zone, that does not mean that they were immune to fire. Climate change and human activities have combined to make wildfires in suburban communities an ever-increasing likelihood.
The Marshall Fire was a grass fire, with flames spreading rapidly over dry grassland that was supposed to be covered by snow by this time of year. Once set, the fire was fueled by wind gusts of over 100 miles per hour coming down the slopes of the mountains. This down-slope wind fueled the fire, but also created intense ember storms that carried the fire quickly towards the towns and from house to house.
Critical to the spread was not just the transfer of embers from one house to another, but the strength of the wind forcing embers through the cracks and vents in people’s homes, causing them to catch fire from the inside.
The intense wind from the mountains is not particularly uncommon, and in a more typical winter season there would likely not have been a fire to fuel. But atypical seasonal weather over the past year combined to make the Marshall Fire as dangerous as it was.
The Front Range region of Colorado experienced a wetter than usual spring this year, promoting an excess growth of grass across the plains. As the year progressed, the higher than usual precipitation turned into intense heat and drought.
According to meteorologist Bob Henson, from September 1 to December 29 the city of Denver experienced its second warmest average temperature in 150 years (52.2 degrees Fahrenheit), its lowest precipitation in 150 years (0.47 inches), and its lowest snowfall in 140 years (0.3 inches), breaking an 87-year record for the latest measurable snowfall in the season and matching an 1887 record for 235 consecutive days without snow.
According to weather data from the National Oceanic and Atmospheric Administration, Boulder, Colorado, just a few miles northwest of Superior and Louisville, received only 0.07 inches of precipitation for the month of November, the lowest amount since 1913. The city should also have received around 30 inches of snow between September and the end of year, but saw just one inch leading up to the fire.
With excess grass, incredibly dry weather, and a lack of snowfall, there were the perfect conditions for a grassland wildfire to ignite and spread rapidly towards a populated area.
As climate change intensifies, wildfires like this are developing more often, even during seasons when they were not previously expected.
Keith Musselman, a snow hydrologist in Boulder told the Associated Press, “With any snow on the ground, this absolutely would not have happened in the way that it did. It was really the grass and the dry landscape that allowed this fire to jump long distances in a short period of time.”
“Everything is kind of crispy,” he added. “In addition to the extreme drought, just 1-or-2-degree warmer days can really dry out the landscape quite a bit more, so everything is that much drier and flammable.”
As the climate warms and changes, the length of the fire season expands, even into the deep winter that was once considered a reprieve.
“I still don’t think winter is ever going to be peak fire season in the West,” said Daniel Swain, a climate scientist at UCLA and the nonprofit Nature Conservancy in an interview with NBC News. “But it used to be a fire non-season, and I really don’t think that’s the case anymore.”
“There’s little doubt in my mind that the conditions conducive to really bad wildfire, whether it’s grass or forest, are only going to get worse,” Jonathan Overpeck, a professor in the School for Environment and Sustainability at the University of Michigan, explained to the AP. “We're building towns and cities and infrastructure and so it’s just a matter of time before we have whole towns burning down like we had in California and events like this in Colorado.”
“Ultimately, things are going to continue to get worse unless we stop climate change.”