Multiple large wildfires, fueled by unusually strong monsoon winds, are currently burning in the Los Angeles area, leaving destruction in their wake.
So far, at least five people have died in those firesMass evacuations, and significant damage to over 2,000 buildings.
Although destructive fire seasons have become increasingly common in California, they are still relatively rare. Major urban areas How Los Angeles is facing fire right now. But as the population increased Communities that are close to plants And open space, experts told Vox, increases the risk of wildfires moving into dense, urban areas. That is compounded by dynamic climate change, which fuels extreme heat and The landscape is parched In areas like Southern California that are already susceptible to wildfires
Combined, these factors mean that wildfires may become more frequent in urban areas – and while cities have few safeguards against these natural disasters, they also contain dangerous sources of fuel.
“[Urban fires] became more common and more severe,” said fire historian and Arizona State professor emeritus Steve Pine. “A problem we thought we fixed has come back.”
What is the risk of wildfires in urban areas?
For areas located near vegetation, as in many parts of Los Angeles, the risk of fire can be high
“In the urban areas of Southern California … we see a very dense, large urban area sitting on top of a highly flammable shrub ecosystem,” said Mark Schwartz, a conservation scientist at the University of California, Davis.
Does this city have existing departments of researchers? Call it the Wildland-Urban Interface, or WUIWhere human development meets “undeveloped wilderness” and vegetation. That means these populated areas are near or intersect natural areas like forests and grasslands.
Such proximity to vegetation—especially in regions like the arid western United States, which are prone to fires—directly increases a city’s risk because fires that typically start in brush and shrubbery can move quickly through abundant fuel sources.
The danger is particularly acute for Los Angeles, because of the stormy winds of Santa Ana About 100 miles per hour — Potential fire carries rapidly from where it starts.
In general, more people are moving into the wilderness-urban interface space, increasing population and activity in these areas, says Noah Dieffenbaugh, a climate scientist at Stanford University. This means more risk to people living there, and a greater chance of a fire starting. Although wildfires are often caused by lightning, most wildfires are caused by humans; Fires in the past have been caused by campfires, irresponsibly discarded cigarettes, or downed power lines.
“Where there are people, there are a lot of ignition sources, and where ignition sources are near vegetation that can burn, that increases the risk,” Diffenbaugh said.
Climate change only amplifies such dangers: The clearest signal that climate change is affecting fire severity is rising temperatures, which lead to more fuel, such as dry vegetation, primed to burn.
Cities that are more “hardscaped” (composed of materials such as concrete and metal) and farther from vegetation sources are less prone to fire. Those with greenery can also make themselves more fire resistant by practices such as prescribed burns (controlled fires simultaneously reduce fire risk and promote healthy vegetation), more native plants, and mitigation of less vegetation near structures.
What fuel sources exist in cities that can fuel large fires?
Houses, as well as plants, can serve as fuel for fires. Other structures, such as natural gas tanks and fuel depots, could be fueled by fires, said Stephanie Pinsetl, a professor of environment and sustainability at the University of California, Los Angeles.
According to Schwartz, “Once a fire moves into an urban area, house-to-house ignition becomes the biggest concern.” Houses made of wood can be flammable, and embers can also be blown into the structure through vents and windows, so a house can catch fire and burn from the inside, even if the exterior is fireproof. Free-standing single-family homes — compared to row homes, which often share walls with neighboring buildings — can be especially vulnerable to fire because of how many exterior-facing walls they have and the different points at which a fire can catch fire, Pinsettle notes.
In cities like Los Angeles, even dry vegetation like palm trees can fuel wildfires.
What’s the worst urban fire damage we’ve seen in recent memory?
The 2018 wildfires in North Central California are the deadliest in the state’s history. It caused 85 deaths, destroyed more than 18,000 structures – including almost completely burning the city of Paradise, California – and burned more than 153,000 acres.
It was so destructive because of similar conditions we’re witnessing in Los Angeles County this week: “There was a high wind pile on top of the dry fuel,” Schwartz said, adding that wind played a particularly important role in spreading the fire. Wired’s Matt Simon explained, Wind helps carry “billions” of embers during campfires, which start smaller fires far from the front line of the main fire. These embers ignited homes and other structures across the sky — making the fire more difficult to contain.
Many homes within Paradise were also more vulnerable to fire. In almost every house in the city Built before 2008, when California imposed a new fire-safe building code that required the use of specific materials for exterior and roof construction, The Los Angeles Times reported.
The leveling of Paradise was destructive: before the fire, About 27,000 people Lived in community. As of 2023, its population was Less than 10,000 (Although it has been resisting since the fire). Wildfires burning in Los Angeles County threaten much more densely populated urban areas: today, about 10 million people live in Los Angeles County.
Both wind and sufficiently dry vegetation have contributed to the growth of recent Los Angeles wildfires, which the area has experienced both. Moderate drought conditions And a huge storm.
Experts say it is “unlikely” that the current wildfires could damage all of Los Angeles, both because of the diversity of the city’s landscape and the precautions it — and other cities — have taken to beef up firefighters and use more fire-resistant construction materials. such as plaster and concrete. “Cities were very, very burning,” Pinsettle said. “Over the decades, we’ve learned to build cities that are much less vulnerable to fire.”
“It used to be back in the late 1800s, for example, that whole cities would be lost because everything was made of the same wood material,” Tim Brown, a researcher at the Desert Research Institute, told Vox. “In today’s built environment, there are a variety of construction materials, especially in urban and commercial centers, that will allow much easier fire control.”
