- If it seems like there are more homes burning in fires every year, it's because there are.

Back in 2005, a mere 245 structures burned in wildfires.

Since, then structure loss has increased exponentially, hitting a 10,000% increase in just 13 years.

Now, obviously the simple explanation is that the acres burned per year in wildfires are going up.

So, there are just more opportunities for homes to ignite.

But that level of simplicity can lead to us taking the wrong actions to keeping our homes safe and our community safe from fire.

According to the scientists we'll talk to in this episode, that probably accounts for a lot of what we've been doing.

- So this disconnect is leading to a solution that's not in the right place.

- So, we're going to dive deeper into research that could fundamentally change how we prepare for wildfire.

(fire crackling) During fire season, you hear politicians and decision makers talking about how there's too much fuel in federal forests after 100 years of fire suppression.

We hear this so often that we don't even stop to consider if the problem of wildfire is really in our forests.

- I mean, it's just part of the common lexicon.

You go back to Smokey Bear, and you see smokey bear in a forested landscape.

What a lot of people don't understand is that the most extensive vegetation type in California is not forest, it's chaparral, and it's grassland.

Contrary to what people believe, the vast majority of structures are lost in the non-forested parts of the state.

- In fact, only 20% of homes recently burned in California were in forests.

And while wildfire is becoming more dangerous to human communities across the West, more homes burn in California each year than in any other state.

But even outside California, public forests don't seem to be the problem.

- As this rapid onset of climate change is, is being realized, you know, we're living it now, it really calls for an assessment of our underlying assumptions about wildfire.

And one of those really is where are fires starting and how are they moving across landscapes?

And often the perception is that our national forests are the source of these large wildfires that impact our communities.

This narrative had built over probably 100 years at this point, and the question had never really been asked in a scientific way: Is this true or not?

We looked at over 22,000 wildfires across 11 Western states.

We found that 60% of fires that cross jurisdictional or ownership boundaries ignited on private lands and moved into the national forest system lands; only 28% coming off the national forest system lands onto other jurisdictions.

- So, rather than private land burning because of fires that start in national forests, it's the other way around.

Most of the time, national forests are burning because of fires that start on private lands.

Looking at this another way, Chris and his team also found that less than 1/4 of the fires that burned large number of homes started on national forest service lands.

The majority started on private lands.

(steady techno music) So, if it's not our public forests that are the problem, why is it that so many homes are burning?

Well, at least part of the answer could be weather.

Some fires are primarily driven by abundant, dry fuels but Alexandra Syphard told us that when there's strong wind, it takes over as the primary driver of fire.

She compared wind-driven versus fuel-driven fires and found an important clue to explain the destruction.

- The vast majority of structures are destroyed in wind-driven fires.

They produce a lot of embers, which can land and rain upon the houses.

And when there are wind-driven, weather-driven fires that are going on, chances are there are multiple fires happening.

And so, firefighter resources tend to be really strained.

And the likelihood that somebody's gonna get to your house becomes slimmer and slimmer the farther out you go.

- So one reason so many homes are burning is that we've misidentified the problem.

We've been trying to address fuels when research shows that's not the primary driver for home loss.

In our very first episode of "Weathered", we looked at how home hardening is one of the most important ways to keep your home safe from a wildfire, and that's still true.

But what Alexandra found is that home hardening is sometimes not enough.

- In the last 30, 40, 50 years, there's been skyrocketing human population growth and urban expansion in Southern California.

I mean, Los Angeles has come to be synonymous with the word sprawl, right?

And, we keep developing farther and farther into the wildland areas.

We keep developing farther and farther to where the fires come from.

- And it's not just California.

The wildland urban interface, where more dense development meets wild area, has seen more new homes built than any other land type throughout the country.

And Alexandra found that how we build in that fringe can mean the difference between home survival and tragedy.

- This here, to me, is the classic fire-prone, Southern California, wildland urban interface landscape.

If you look around you, the whole surrounding area is this dense shrubland landscape, and we're also in a wind corridor.

And it's a nice compact development surrounded by wildland vegetation.

The studies I've done show time and time again that structures tend to be destroyed at lower housing densities, which is where there tends to be more edge between the houses and the vegetation, and there is more difficult firefighter access.

- Low housing density is what a lot of us imagine when we think about wildfires.

You have houses sitting by themselves in a forest, or as we know is more dangerous, grassland, but surprisingly there have been studies that contradict this understanding.

They show that sometimes high housing density can lead to a worst case scenario and catastrophic loss.

- If you have a development like this, you can have high density housing within, and the relationship can flip.

You can have a situation where the homes actually become the fuel for the fire and the fire can spread from house to house.

And this is what happened in the Tubbs Fire with Coffey Park.

It's what happened in Paradise.

The fire came from outside the development, but the development's like a little island in the sea of flammable vegetation.

In these wind-driven fires, there's millions of little embers flying through the air in these 100 kilometer an hour winds, and whatever they land on, if it's flammable, that ignites and keeps the fire going.

It comes down to exposure.

When you have edge, you're exposed to the fire.

- And we build these suburban developments with lots of edge all over the place, which poses an increased risk as much of the world becomes hotter and drier.

- What we have right here, we've got this sort of elongated, edgy development, but then, you also have this leapfrog pattern where up on the next ridge, you have another little development, and then you go to the next ridge and you have yet another little development.

You can easily see a wind channeling down this corridor, heading toward the coast, which is the direction that the wind tends to blow and anything that's in the path of these wind-driven fires in this dense vegetation is, you know, susceptible to burning.

- [Maiya] In the island development of Talent, Oregon, 2,500 homes were destroyed by the Almeda Fire in 2020.

And the Marshall Fire burned 1000 homes in Colorado in 2021, as fire burned grassland in between neighborhoods.

But, we have a national housing shortage.

More and more homes are gonna be built and should be built.

So now's the time to figure out how we can keep homes from burning in wildfires.

Alexandra's research clearly shows the safest and most risky patterns of development.

- You can think of it in terms of one, infill, which is where you put the new development within an existing development; two, expansion, which is where you develop outside of an existing development, where one end is part of the old development and the new end is what has the edge.

And then the worst thing you can do is leapfrogging little, new, developing clusters of development out in the wildlands.

- So, how might we stop homes from burning?

First, we could prioritize new construction inside existing developments and between leapfrog islands to decrease the vulnerable edges.

Then Alexandra and Chris suggested thinking about what types of land use can be a buffer between wildlands and communities, things we already irrigate, like orchards, vineyards, and even golf courses could be cited around communities as a fire buffer.

This, combined with home hardening we've explained in previous episodes, would go a long way to addressing our wildfire crisis.

Do you live in an area that's prone to wildfire?

Is your community taking steps to keep you safe?

Let us know in the comments.

(slow soft music)