Why are trees still standing next to burned-out buildings in Los Angeles? The answer is simple

When people think of wildfires, burning trees are likely the first image that comes to mind.

So when a city burns and trees are left standing, it may seem unusual at first glance.

Several massive wildfires have torn through Los Angeles since Tuesday, killing a least 10 people and burning down more than 10,000 homes and other structures in a 40-kilometre expanse north of the city's downtown.

As images of the fires dominate the media this week, some are questioning why trees, including the state's iconic palms, have survived next to burned-out homes and cars.

This is fuelling conspiracy theories on social media about homes and structures being targeted — with some people saying there is no way a fire would naturally leave trees standing and suggesting structures were instead directly attacked by secret weapons.

A downed power line is shown on a street following the Palisades Fire on Friday. (David Ryder/Reuters)

Internet personality The Patriot Voice posted to his 141,000 followers on social media platform X that photos showing standing trees provide proof that the U.S. government "is PURPOSELY setting fires using Military grade DEWs [direct energy weapons] in these areas to initiate a MASSIVE LAND GRAB."

Others have claimed it is evidence of HAARP (High-frequency Active Auroral Research Program) microwaves, with one X user saying they are "incendiary towards metal" in homes, but, "Trees have no metal inside, so much harder for trees to burn from microwaves."

Mads Palsvig, the head of Denmark's right-wing Prosperity Party, wrote on X, "Forrest [sic] fires where trees don't burn. It is called DEW. Always nice spots prime real estate."

It all comes down to moisture

The claim that trees aren't burning is simply not true, as evidenced by numerous videos and photographs showing that many have gone up in flames, in some cases wreaking havoc on nearby buildings.

But scientists say there is a simple explanation for why some have been spared that fate.

A palm tree burns as winds fuel the Eaton Fire in Altadena, Calif., on Wednesday. (David Swanson/Reuters)

"I mean, it's pretty obvious to me. Trees are filled with thousands and thousands of litres of water," said biology and biotechnology professor Miranda Hart, with the Okanagan Institute for Biodiversity, Resilience and Ecosystems Services at the University of British Columbia.

"Of course trees burn when fires are big and hot enough. But if there's a tree filled with water and something really dry beside it, the thing that was dry is going to burn first. So in that way, you can imagine the fire could just kind of go around if there's enough fuel on either side of it."

Similar questions arose after the town of Paradise, Calif., burned down in a 2018 wildfire. At the time, a retired U.S. Forest Service scientist told CBC News that while some people might imagine a wildfire as a wall of flames, burning embers ignite many spot fires over a wide area — which helps explain why in some photos, it looked almost as though there were hundreds of individual house fires rather than one large fire.

After a 2007 wildfire, the fire department in Escondido, Calif., recommended restrictions for planting palm trees specifically after determining that certain species, due to their form or lack of maintenance, were especially hazardous.

Palm trees frame a house as it goes up in flames from the Woolsey wildfire in 2018, above Pacific Coast Highway in Malibu, Calif. (Reed Saxon/The Associated Press)

Palms that are not well maintained "can explode into a giant torch," the document says, a phenomenon that can be seen in videos from the current L.A. wildfires. It says flying embers can also embed themselves into the fibrous tissue or leaf bases along the trunk of a palm tree.

Another major hazard is leaf bases and dried fronds on trees that are not maintained can detach from the trunk and be carried on the wind, acting like a fireball.

Kevin Hanna, director of the Centre for Environmental Assessment Research at UBC, said certain trees are more fire-prone than others — deciduous trees and shrubs, for example, are less flammable because of their moist leaves and lower resin content, while conifers like decorative cedars or junipers are highly flammable.

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As for why some trees and buildings survive when others don't, he said it often comes down to momentary conditions, and "what some might call chance or serendipity," like a quick shift in wind that can redirect embers.

Maintaining a wet lawn, or having a wet or fire-resistant roof can make a difference, Hanna said, although in extreme enough conditions, nearly everything will burn.

"There's no conspiracy — just some politicians resorting to tawdry opportunism, denying the reality of climate change and shifting blame onto others in the hope of gaining a fleeting advantage," he said.

Climate change, development adding to risk

Hanna said housing development has expanded further into fire-prone areas in recent years, increasing the risk of houses burning, while wildfires become larger and more frequent, owing in part to droughts and warmer weather exacerbated by climate change.

While some have blamed a lack of fireproofing and brush removal, UBC's Hart said the truth is that conditions were perfect for the fires to spread and little can be done to prevent similar destruction in the future aside from trying to reverse climate change.

"Fire is not that mysterious. It just needs the right conditions and appropriate fuel," Hart said.

"We can rearrange deck chairs on the Titanic for a few more years, but we can't build a society resilient to climate change. It's too powerful and it's too multifaceted."