With the fires now fully contained, residents have returned home to find nothing but scorched foundations. Officials are still on the hunt for hundreds of missing people – a process made more difficult by the onslaught of rain.
In the aftermath of the blazes, many are demanding to know how they got started.
Determining the cause of a wildfire can take months of investigation, which includes scouring the charred soil for clues.
In the meantime, conspiracy theorists have taken to YouTube to posit their own explanations.
Crazy wildfire theories
The most widely circulated theory seems to have originated with the far-right conspiracy group QAnon, which often propagates wild assertions about Hollywood actors and high-ranking officials.
The group is now claiming that the California wildfires were caused by lasers or directed energy weapons manipulated by the US government.
Last year's wildfires yielded similarly bogus claims, which spread across YouTube and other platforms.
To set the record straight, we talked to Marko Bourne, a former Federal Emergency Management Agency (FEMA) official who now leads Booz Allen Hamilton's emergency management, disaster assistance, and risk practice.
Like most scientists, Bourne attributed the wildfires to a combination of weather and human activity.
By building on land that is susceptible to wildfires – namely, forested areas – humans have essentially put themselves in harm's way.
"While forest fires have always happened, [people] have impinged into areas that are prone to fire," he said.
"Now we're being impacted by those fires directly, where we wouldn't have [been before]."
Of the few natural causes of wildfires, lighting strikes are the most common. There's also the possibility that fires can be started by power lines.
Bourne said that's an atypical scenario, though it may have been the cause of last year's Camp Fire in California wine country.
The vast majority of wildfires in the US are caused by human activities such as neglecting campfires, flinging cigarette butts, burning debris, or committing arson.
But not every one of these errors can ignite a flame. Dry, windy conditions and low humidity tends to encourage the spread of wildfires and make them harder to control.
Fires also require some sort of ammunition.
"Wildfires have occurred, and continue to occur, in areas where there's fuel," said Bourne. That fuel may be dry leaves, trees, underbrush – or, in some cases, homes.
How to explain the flames
One of the main questions among YouTube conspiracists is why the California fires destroyed certain homes and not others.
"You'll notice here that stores and restaurants are wiped out, while other things are still in perfect shape," one YouTuber, who goes by the name ODD Reality, said in a video clip.
"Other buildings are fine, trees are untouched, but specific structures are just devastated. You gotta ask yourself, what's up with that?"
Wildfire experts have a pretty clear answer.
"Once a wildfire gets going, they create almost their own weather patterns," said Bourne.
When a fire ignites, its embers can be dispersed by the wind. If they blow toward a house with broken or open windows, flammable landscape materials, or gutters littered with debris, they can begin to smolder and start a flame.
"Most everything we use in home construction can burn," said Bourne. "Some materials like steel and concrete and brick don't burn per se, but our homes will always have flammable materials."
Bourne noted that materials used in today's construction, such as plastics and laminates, can become exceptionally hot, while older construction doesn't burn as readily.
But there's another factor to consider – one that the conspiracists have already attempted to shoot down.
A recent climate change report published by the Trump administration finds that extreme temperatures caused by human activity could increase the length and magnitude of wildfire season in the Pacific Northwest.
The report also cites a 2016 study, which found that climate change nearly doubled the area of western forests that were burned between 1984 and 2015.
To top it off, extreme temperatures are expected to increase fire frequency in the southeast.
While weather conditions certainly contribute to wildfires, greenhouse gases are making this weather more extreme.
That means we can expect more blazes in the future – and more conspiracy theories to go along with them.
This article was originally published by Business Insider.
More from Business Insider: