(Bloomberg) -- Thousands have fled as wildfires spread across the Los Angeles region. What ignited the Palisades and Eaton Fires — the two main blazes — is still under investigation but weather conditions have helped fuel their spread. So, too, has where they ignited, in what experts call the wildland-urban interface.
An increasing number of people around the US now live in that transition zone where open lands meet human development, and it’s becoming more dangerous as climate change fuels more intense fires.
Pacific Palisades is a prime example of what happens when a fire ignites in the wildland-urban interface, or WUI. What began as a brush fire on Tuesday became a major blaze destroying at least 1,000 structures in and around the tony Los Angeles neighborhood nestled between Malibu and Santa Monica. The Eaton Fire is also burning in a similar environment in Altadena and Pasadena to the east, with at least another 1,000 buildings damaged or destroyed.
California has seen a number of these types of blaze in recent years, notably the 2018 Camp Fire, which began as a wildland fire that overtook the town of Paradise and damaged or destroyed 18,000 structures, including 9,000 homes. It also left 85 dead making it the deadliest US wildfire in 100 years.
What makes WUI zones susceptible to wildfires is the combination of open space, parks and houses, says Crystal Kolden, the director of the Fire Resilience Center at the University of California, Merced. “Many of those houses and subdivisions are laid out in ways that have lots of highly flammable shrubs and trees growing on and in-between lots,” Kolden says. “So fire burns exceptionally well in this area because the vegetation throws embers that land on houses, the houses catch fire and produce more embers.”
Yet despite the risks, more people are living in the WUI. Research shows that between 1990 and 2010, 25 million people moved there and 12.7 million homes were built.
In part that’s a response to high housing costs elsewhere and a desire to live in “proximity to nature,” says Rebecca Paterson, a spokesperson for the National Interagency Fire Center, the US wildfire logistics and coordination body. At the same time, studies indicate that access to green space commands higher housing prices. In the Pacific Palisades, which is known for its strip of coastline and abundant parks and hiking trails, Zillow lists the average home value at $3.4 million.
That growth “definitely creates a lot of challenges, especially with managing wildfires,” Paterson adds.
So many people abandoned their cars in Pacific Palisades that emergency crews brought in bulldozers to clear the way for firefighters. The Palisades and Eaton Fires have also stretched response efforts dangerously thin as they spread in urban areas.
“If a fire breaks out in just the wildlands with no homes or infrastructure nearby, obviously we want to protect those resources, but it's going to be less of an urgent situation than if lives and homes are on the line,” says Paterson.
State agency CalFire has guidelines on creating defensible space around properties by clearing vegetation, and doing basic tasks like cleaning gutters and blocking attic vents with fine screens to make homes less likely to burn. California is also in the process of drafting defensible space rules known as Zone Zero.
Yet the odds of major fires will only increase because of climate change.
The growth of the WUI and explosive fires has led in part to an insurer exodus. The estimated payouts for auto, residential and property insurance claims from the Camp Fire totaled between $8.5 billion to $10 billion, the Insurance Information Institute estimated at the time. The Palisades Fire alone may end up dwarfing that.
High-value home owners, including some in Pacific Palisades, are increasingly turning to a less regulated form of insurance called non-admitted insurance typically used to insure especially risky properties like fireworks factories.
The state-backed FAIR Plan has helped fill some gaps for less wealthy homeowners, though even those policies can be “exorbitantly expensive” says Kolden. “This is why you hear about so many homeowners being uninsured in these fires — they simply can’t afford fire insurance.”
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