Millions of Homes Are Being Built in Harm’s Way Even as Wildfires Grow

Wildfires are becoming larger and more severe across the Western United States as global warming intensifies. At the same time, new data show that more Americans than ever are moving to areas of the country that are more likely to burn, increasing the likelihood of disaster.

Source: NY Times | Published on September 9, 2022

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More than 16 million homes in the West were located in fire-prone areas near forests, grasslands, and shrub lands in 2020, where the risks of conflagration were greatest. According to research published Friday by the University of Wisconsin-Madison and the United States Forest Service, this is an increase from roughly 10 million homes in 1990.

"That's the perfect storm," said Volker Radeloff, a forest ecology professor at the University of Wisconsin-Madison who collaborated on the study. "Millions of houses have been built in places that will eventually burn," he said, despite the fact that climate change is increasing the risk of major wildfires across the West due to extreme heat and dryness.

This dynamic is most visible in California, where eight of the largest fires on record have occurred in the last five years. The state now has approximately 5.1 million homes in what is known as the "wildland-urban interface," or areas on the outskirts of cities where houses and other development are built near or among flammable wild vegetation.

The Sierra Nevada foothills have seen particularly rapid growth.

When wildfires erupt, they usually cause the most damage in these transitional zones, where homes and businesses encroach on otherwise undeveloped wilderness.

Examples include the 2018 Camp Fire, which destroyed the forest-surrounded town of Paradise, Calif., and the Woolsey Fire, which destroyed more than 1,600 structures in the canyons northwest of Los Angeles.

There is no single cause for the rapid growth in the wildland-urban interface, or WUI (pronounced "woo-ee"). Some people relocate to be closer to nature or because the cost of living is lower. Many cities in California have limited development in denser downtown areas, exacerbating the state's housing crisis and pushing people to the outskirts.

"By and large, most new development housing construction in California has occurred on the outskirts of existing urban areas," said Karen Chapple, a city and regional planning professor at the University of California, Berkeley, and co-author of a report on rebuilding after wildfire disasters. "It's happening because the land is cheap there." As a result, we end up putting housing in these extremely vulnerable areas."

Throughout the West, similar trends can be observed. Since 1990, the number of homes built in the wildland-urban interface in Colorado has nearly doubled to more than one million. The Front Range, where the number of large, high-severity fires has increased in recent decades, has seen some of the fastest growth.

Texas now has 3.2 million WUI homes, making it the state with the fastest growth over the last decade. While some of Texas' most destructive wildfires have occurred in forests, many of the state's wildlands are made up of grasses and shrubs, where fires can spread more quickly and often cause more damage. The state climatologist's office warned last year that wildfire risks were increasing as the state dries out.

The rapid development of housing in flammable areas is one of the primary reasons why wildfires have become more destructive over time. Not only are homes more likely to burn, but more people living near forests and grasslands increase the likelihood of fires starting in the first place. While lightning frequently starts wildfires, humans cause the vast majority of ignitions, often by accident: a cigarette thrown out the window, or a vehicle's muffler catching fire on dry grass.

More homes in fire-prone areas increase the demand for firefighting in often difficult terrain, which can stretch fire suppression resources thin and lead to a dangerous buildup of vegetation in areas that experts say would benefit from low-level burning more frequently. Wildfires have long been a natural part of the Western landscape, becoming disasters only when people are in their path.

"The more homes we have in the wildlands, the more people we have to protect, and the more people who need to be evacuated," said Miranda H. Mockrin, a research scientist with the US Forest Service who worked on the new study. "It becomes more difficult."

According to the researchers, 136,000 homes were within the perimeter of Western wildfires in the 2010s, compared to less than 31,000 in the 1990s. Some of the increase can be attributed to the fact that fires are consuming larger and larger areas of land. However, one-quarter of the homes threatened by wildfires in the last decade did not exist in the 1990s, indicating that housing growth in wildfire territory was a major contributor to the increase in fire danger.

"We're dealing with a two-headed monster," said Stephen M. Strader, a disaster scientist at Villanova University who was not involved in the study. "On one hand, there is a changing environment, and climate change is altering the atmosphere. But, if you look at that alone, you miss the other side: society is changing, our cities are changing, and our land is changing."

"When all of these conditions combine," he says, "it creates a more disaster-prone society."

While the new data only extends through 2020, a separate report by Redfin, a Seattle-based real estate brokerage, found that demand for homes in fire-prone areas has increased since the coronavirus pandemic began, as remote work enabled Americans to relocate further from job centers.

According to wildfire experts, Western states will never be able to stop all growth in the wildland-urban interface. However, in addition to efforts to improve forest management in these areas, governments could impose tighter restrictions on future development to ensure communities are better protected against unavoidable fire dangers.

"So much of the West is wildfire-prone that saying you shouldn't live anywhere there's a risk is a non-starter," said Molly Mowery, executive director of the Community Wildfire Planning Center, a Denver-based nonprofit. "It's far more productive to concentrate on what we can do to protect our homes and neighborhoods if a fire does break out."

Creating more "defensible space" around homes and neighborhoods, cleared of brush and vegetation, can help keep blazes at bay. It would imply designing homes to be more resistant to burning embers carried by the wind, which frequently cause structural fires by blowing into homes through vents in the eaves or sides.

California adopted some of the strictest rules in the country for new homes in high-risk fire areas in 2008, requiring developers to use fire-resistant materials and provide firefighters with access to water. These rules have the potential to make a difference. Following the Camp Fire, one study discovered that approximately 51% of the 350 single-family homes in Paradise built to the new codes escaped damage, compared to only 18% of the 12,100 homes built before the standards.

However, most Western states lack statewide codes, and it is usually up to local governments to enforce their own standards. Austin, Texas, one of the country's fastest-growing cities, took matters into its own hands in 2019, enacting stringent rules for new homes in the WUI, such as noncombustible screens over attic vents and safe propane tank storage.

However, new construction building codes only go so far because they do not address the millions of vulnerable homes that have already been built. Properly protecting an existing home can be costly, costing up to $27,000, so governments may need to step in to assist.

For the time being, progress is patchy. Many regions have resisted new regulations, warning that they will raise housing costs. Even after a wildfire has destroyed a community, there is intense pressure to rebuild quickly and without adding new requirements.

"Too many places are still operating under the mindset that if there's a wildfire, the firefighters will come and save their homes," said Kimiko Barrett, a wildfire researcher at Headwaters Economics, a nonprofit research group. "Once we realize we're not going to be able to put out every last fire, we can think about how to live with wildfire."

There are some indications that things are changing. After the Marshall Fire in Boulder in late 2021 destroyed over 1,000 buildings, Colorado lawmakers began discussing new statewide codes, though none were adopted. In fact, over the last decade, California has added more homes outside of the WUI than within it. Dr. Radeloff said it's too early to tell if this is a sign of shifting attitudes toward fire risk.

"It's a lovely place to live," Dr. Radeloff said of the wildland-urban interface. "However, as a society, we really need to get our heads around what living so close to nature entails."