The traditional way — and the easiest way — to compare wildfire seasons is the number of acres burned. That figure is fairly straightforward and reliable, at least for data within the last 35 years; before 1984 the data is questionable.
But blackened acres does not tell the whole story about the effects of fires on humans. A 50,000-acre fire in a northwestern California wilderness area has fewer direct impacts on the population than, for instance, the 3,200-acre Almeda Fire that destroyed 2,357 residences in Southern Oregon a few months ago.
Headwaters Economics has built a user friendly interactive data base of the number of structures, by state, destroyed by wildfires from 2005 to 2020. It presumably includes all structures, including back yard sheds, other outbuildings, commercial buildings, and residences.
Here are three screenshots, examples for the entire U.S., Colorado, and Montana.
The best way to prevent homes from being destroyed in a wildfire is not clear cutting or prescribed burning a forest, it is the homeowner reducing flammable material in the Home Ignition Zone. This includes spacing the crowns of trees at least 18 feet apart that are within 30 feet of the home, 12 feet apart at 30 to 60 feet, and 6 feet apart at 60 to 100 feet. The envelope of the structure itself must be fire resistant, including the roof, vents, siding, doors, windows, foundation, fences, eaves, and decks. A FEMA publication (13 MB) has excellent detailed recommendations. Headwaters Economics found that the cost of building a fire-resistant home is about the same as a standard home. When implemented, Chapter 7A of the California Building Code, regulates these features.
For more information: Six things that need to be done to protect fire-prone communities.
And, Community destruction during extreme wildfires is a home ignition problem. Here is an excerpt from the article written by Jack Cohen and Dave Strohmaier:
Uncontrollable extreme wildfires are inevitable; however, by reducing home ignition potential within the Home Ignition Zone we can create ignition resistant homes and communities. Thus, community wildfire risk should be defined as a home ignition problem, not a wildfire control problem. Unfortunately, protecting communities from wildfire by reducing home ignition potential runs counter to established orthodoxy.
Y’all took the words right out of my mouth–I couldn’t agree more!
But perhaps I tried to truncate my post too much or failed to cover all the bases–I did both.
Radiant heat can raise the temperature of a house to just shy of, say, 435F and the first firebrand to hit it will light it off. I wasn’t suggesting a simple zero or one function, I was intending to talk about trends–the whole relevant context. Houses burning next to houses are a different can of worms. They burn hotter and longer than wildland fires, and some of the airborne burning material can travel farther and last longer than most anything that comes out of the “brush.”
The fire devil truly is in the details.
There has been an enormous amount of residential development in the wildland urban interface in every western state over the last 20+ years. There are also around 50 million more people living in the US since 2000. The whole situation will only get worse when all factors are considered.
My cousin was affected by the Santa Cruz fire this year. Their house survived but numerous neighbors were burned out completely and one neighbor died in the fire. They are still trying to get power restored to the house. They are living about an hour away in an apartment provided by the insurance and have to commute to the home to continue repairs. In some ways, the continuing mental strains are worse than the initial frantic evacuation. They were also fortunate to have about 11 thousand gallons of onsite water the firefighters could use and they had worked assiduously over the years to create and maintain defensible space.
Your house could be blocks in from the flaming front with all the clearances provided, and it still may burn because of the house next to it and so on. Even fire resistant homes are not completely safe from radiant heat when the winds blow. Not sure what the answer is, except to accept the risk or move.
I first got started on the management end of things in 1970 with the Kitchen Creek fire. I pulled a “task force” together from several of the local, county, state, and federal fire agencies. I sort of camped out at the western region fire lab (Eamor Nord, Clive Countryman, and others), and wrote a Fire Hazard Reduction and Open Space Management Preliminary Plan. It included a similar vegetation management scenario that I called the “Fuel Density Gradient,” starting at the house with landscaping out to thirty feet (the distance the fire researchers at the time said was (and it was the law) was the distance from the structure the fire had to be to avoid ignition by radiation and/or convection. The additional zones (I believe there were three) had increasingly lighter requirements out to 330 feet from structures. I was sorta right and sorta wrong. I believe that “clearing” is the wrong word, but the firefighters I’ve talked to refuse to change their approach. What results is a weed patch of flashy fuels–weeds and soil erosion. When I had a lot on a canyon, I had a jade-plant (won’t work in other places; every site is context-driven) fire barrier behind the property line, providing a fireproof raindrop interceptor, stemflow regulator, and gap between the chamise and the carefully trimmed indigenous vegetation, separating the fuels vertically and horizontally, aiming for a flame-length of two feet or less, and certainly one that is irregular in flame length due to the irregular fuels. Evey year, we would take a small dump truck of trimmings. The house was plaster, including the eaves. There was a block wall between the treated native vegetation and the yard. I placed sprinklers on the wood deck wetted it and kept the bay windows cool. No other combustibles.
Headwaters is always digging in so well….impressive stuff…love that our tree density should follow appropriate social distancing protocols…
Is structures burned the proper metric to gauge impacts?
I’ll saw no.. Is the loss of a multimillion $ log deck, loss of critical endangered species habitat, secondary impacts from post fire landslides, loss from time spent evacuated, or economic loss from long term road closures all better or should be factored into yearly fire impacts.
Good start to an important discussion.
You’re right, Bob. There are many factors that should be considered. Here’s a few.