What role does LA housing development play in wildfire risk?

Fierce winds and months of drought created the conditions for devastating wildfires in Los Angeles this month. But the growth of housing in and around the city's fire-prone hills over the past few decades also played a big role.

Most of the homes damaged or destroyed so far were located on or near hillsides covered with highly flammable vegetation. Even dense urban areas like Altadena were vulnerable to embers blown from nearby burning hills.

Across the country, including California, millions of Americans are moving into fire-prone areas, especially developed areas on the outskirts of cities that run into forests, grasslands, and brushlands. Rapid growth in these areas, known as the “wildland-urban interface,” leads to devastating fires, especially as climate change spurs larger and more intense wildfires across the West. The odds are increasing.

Between 1990 and 2020, the number of homes in California's fire-prone regions increased by 40 percent, according to a study led by Volker Radelof, a professor of forest ecology at the University of Wisconsin-Madison. In contrast, the number of homes in less combustible areas, such as downtown, increased by only 23%.

There are currently more than 16 million homes located at the wilderness-urban interface, or WUI (pronounced “woo-ee”), across the West.

When wildfires occur, they tend to cause the most damage in these areas where development is encroaching on nature. An example of this is last week's Palisades fire. In this fire, the wildfire quickly spread through 1,000 homes and buildings in an upscale residential area. Or the 2018 Camp Fire that burned through the forested town of Paradise, California.

If someone had walked through these areas a week before the fire, they would never have thought it was a fire risk, Dr. Radeloff said. “It seems like it's too far away from natural vegetation, but it's not. Fire scientists know that's not the case.”

Americans often move to the WUI to be closer to nature or because housing is cheaper. In California, many cities have restricted development in their downtown areas, pushing people to the periphery. Mobile homes and low-income housing are popular in fire-prone areas.

While Los Angeles County as a whole has seen population declines since the pandemic accelerated people moving away from urban centers in 2020, both Palisades and Altadena counties have seen modest increases.

Approximately 1 in 8 properties in California currently face a “very high” fire risk, according to data from CoreLogic, a real estate and risk analysis firm. In Los Angeles County, that number is closer to 1 in 10, making new buildings slightly more likely to be located in wildfire-prone areas than buildings built before 2000.

“Especially in the Western United States, over the last few decades we've grown into a kind of gangbusters participating in the WUI,” said Andrew Lambak, a senior fellow at the nonprofit Urban Institute. “Wildfire exposure is getting higher and higher.”

The increase in housing in flammable areas is a major reason why wildfire damage is increasing. Not only are more homes in the path of a fire, but more people are living near forests and grasslands, making it more likely that a fire will start in the first place. Most wildfires are started by humans themselves. A cigarette thrown out the window or a hot lawnmower engine igniting dry grass.

More housing in fire-prone areas also increases the demand for firefighting in often difficult terrain, which can lead to a shortage of firefighting resources.

Urban sprawl wasn't the only reason the Los Angeles fires caused so much damage. Many of the homes in the Pacific Palisades are 40 to 100 years old and have survived years of damage in an area where fires occur frequently, said Crystal Colden, director of the Center for Fire Resistance at the University of California, Merced. It is said that

But this time we had more fuel and stronger winds. Much of the surrounding area was once ranchland, with cattle grazing controlling the growth of flammable shrubs and grasses. Part of the land was then converted into a park and reserve to allow more plants to grow. A brutal drought (Los Angeles hasn't had rain in eight months) and Santa Ana's hurricane-force winds added fuel to this week's devastating fires.

“People will return there because the Palisades is a really beautiful place,” Dr. Colden said. “My hope is that they stop and ask themselves how they can bounce back better so something like this never happens again.”

Learning to “coexist” with fire

It's hard to imagine that millions of Americans would suddenly no longer live near wilderness. That's why it's important to do more to protect homes and communities from fire.

“We need to start seeing these wildfires as inevitable and learn how to coexist with them,” said Max Moritz, a wildfire expert at the University of California, Santa Barbara.

Protection measures include building homes that are more fortified against wind-borne embers that can blow into the home through eaves and side vents. That includes creating more “defensible space” around homes and neighborhoods by clearing brush and vegetation to keep fires away, said Anne Cope, chief engineer at the Insurance Institute for Business and Home Safety.

Since 2008, California has had some of the strictest rules in the country for new homes in high-fire-risk areas, requiring developers to use fire-resistant materials and provide water to firefighters. Another rule, adopted in 2023 but not yet in effect, would require homeowners in fire-prone areas to remove flammable materials such as brush and wooden fences within 5 feet of their homes. . Dr Moritz said some regions use orchards, farmland and other buffers against invading forest fires.

Such actions can make a difference. After the Camp Fire, one analysis found that about 51% of the 350 single-family homes in Paradise built to the new standards were spared, compared to just 18% of the 12,100 homes built before the standards. It was %.

But new rules take time to take effect, building codes don't apply to older homes, and renovations can be expensive. Many Western states outside of California do not have a statewide code, leaving enforcement of standards to local governments.

In many cases, experts say, homeowners, state agencies and the federal government need to do more to prevent vegetation from accumulating around high-risk areas. It's not always easy. According to the National Park Service, using prescribed fire to suppress vegetation is not effective in places like the Santa Monica Mountains near the Pacific Palisades. In other regions, labor shortages and environmental regulations are hampering forest thinning efforts.

States could also impose stricter restrictions on development in some of the highest-risk areas. Some governments pay to evacuate people from land that repeatedly floods, but that idea is rarely considered for wildfires.

At the same time, California faces a severe housing shortage, and experts say any restrictions on development should be combined with efforts to allow more housing to be built in lower-risk areas such as urban centers. states that it is necessary.

“Encouraging urban landfill development to reduce pressure on WUI areas is a big part of the equation,” said CJ Gabbeh, an environmental scientist at Santa Clara University.

hurry to rebuild

When a fire hits a neighborhood, many residents want to rebuild quickly with few restrictions. After the 2022 Marshall Fire near Boulder, Colorado, some communities agreed to stricter building codes, but others cited higher costs and recommended using fire-resistant materials and installing sprinklers in rebuilt homes. He said he opposed requirements such as the establishment of a Rumbach of the Urban Research Institute.

“People want safety, but cost and the ability to rebuild quickly are also important to recovery,” Rumbak said. “I often see tension between the two of them.”

Rising home insurance costs may force changes. Dr. Colden, of the University of California, Merced, said as insurance companies retreat from California's fire-prone areas and premiums soar, many communities may consider ways to significantly lower their risk.

After the Painted Cave Fire burned 427 homes and killed one person in Santa Barbara, California, in 1990, the nearby community of Montecito took action. Local fire districts are currently working with residents to make homes more fireproof, calling for changes to building codes that include thinning native shrubs on private property and widening driveways for fire trucks. .

These efforts were put to the test during the 2017 Thomas Fire. At that time, strong winds caused flames to burst onto Montecito's doorstep. This time, only seven houses were destroyed.

“There are many disasters that are out of our control,” Dr. Colden said. “But fire is something we can control. We can control the fuel. We can control what the structure is like.”

“It's hard to maintain that momentum when it's not fire season,” she added. “But now, post-disaster, every other community that is at some kind of fire risk should look at what can be changed and say, 'Today is the day to start.'”