CNN  — 

Ed Nordskog never wanted to work on arson; his heart was set on becoming a homicide detective. But when an arson investigator position came up in the LA County Sheriff’s Department, the money was good and he took it.

He quickly found himself completely sucked in. “It fascinated me, the arsonists were truly really odd criminals,” he told CNN. He spent the next two decades immersed in their world. In retirement he has found his expert insight into the minds of arsonists in high demand due to a string of arson arrests in the wake of the deadly Los Angeles fires.

While the fires’ causes are still being investigated — and experts, including Nordskog, believe arson is highly unlikely to be behind the biggest blazes — the arrests have put a spotlight on the question of why people deliberately set fires.

In pictures: Deadly wildfires in Los Angeles County

It turns out it’s a very tough one to answer.

There is no such thing as a typical arsonist; anybody and everybody commits arson for a slew of different reasons, Nordskog said. “It’s a very odd crime that just a few people understand.”

Psychologists point to some common characteristics: problems communicating, impulsive behaviors, difficulty expressing emotions and an interest in fire paraphernalia. Yet motives are often multiple and can be slippery to pin down.

“We are still learning about the psychology of arson,” said Nichola Tyler, a senior lecturer in forensic psychology at Swinburne University of Technology in Australia.

But there is growing urgency to better understand arson in order to tackle it. People are by far the biggest cause of fires and arson is significant factor. Roughly 20% of human-caused wildland fires in the US are set deliberately.

As humans continue to warm the planet, increasing and worsening dangerous fire weather, it further raises the risk of arsonists setting catastrophic wildland fires.

A complex tangle of motives

Many people are fascinated by fire from a young age.

It’s fairly common for children to play with fire, said Caoilte Ó Ciardha, a senior lecturer in forensic psychology at the University of Kent. Adults often continue to enjoy it — cozy firepits, flickering candles, beach bonfires — but most age out of unsafe fire play.

For a small minority, however, fire offers something different and darker.

For some, it’s a means to an end. These are usually the one-and-done arsonists, Nordskog said. It’s the person who burns their car because they want the insurance money, or the business owner who sets fire to their office to destroy paperwork.

Outdoor fires and serial fire-setters are a different story.

While arson arrests during the LA fires piqued people’s interest, arson happens every single day in every big city, Nordskog said. Think dumpster fires, car fires and people burning garbage in alleys. Nobody cares until there is a wildfire happening at the same time, he said.

Motivations for these urban fires are hugely varied. One woman arrested for allegedly setting fire to piles of trash during the LA fires said “she enjoyed causing chaos and destruction,” according to Jim McDonnell, chief of the Los Angeles Police Department, speaking at a January news conference.

Seeing fire, or the emergency response to it, can stimulate people, said Tyler. But many experts say a desire to cause chaos is a rare motive. Surging homelessness, and the complex tangle of severe mental health problems the population endures, appears to be a much bigger factor.

Many unhoused people accidentally set fires while cooking or trying to keep warm, but there is also a “significant” and growing proportion of serial arsonists among them, Nordskog said. In LA, he pins this in part on a burgeoning use of meth, which can cause serious mental health problems including psychosis.

Across the US “we’re seeing a lot of fires that are caused by folks with mental health issues,” said Scott Fischer, a retired federal arson investigator. He recalled a meth user who was convinced there were people living underground that meant him harm. “So, he started a fire to try and smoke them out,” Fischer told CNN.

For the most part, these kinds of urban fires don’t cause extensive damage, Nordskog said. Many of those who set them have no interest in the fire itself. They often walk away afterward with little thought about what it might become.

‘An atomic bomb at their fingertips’

There’s another much smaller but far more dangerous subset of arsonists: serial wildland arsonists.

They are rare, but are “the worst of the worst,” Nordskog said. “A true wildland serial arsonist has the power of an atomic bomb at their fingertips. No criminal in the world has that kind of power.”

They tend to plan the event and take steps not to get caught, such as turning off their cellphones and using time-delayed incendiary devices, giving them time to get away.

As with all arsonists, their motives vary, Nordskog said. For some it can be about power or anger, for others financial gain or excitement.

In a surprising twist, firefighters make up a significant percentage of this group. Roughly a third of wildland arsonists are connected to the fire service, Nordskog said.

In 2008, Robert Eason, a volunteer firefighter, received a 40-year sentence for setting more than a dozen wildland fires in northern California. He was accused of using a coil-shaped time-delayed incendiary device that allowed him to escape the scene long before the fire took hold. Investigators suspect he may have set more than 100 fires over nearly two decades.

Eason’s motives are unknown, he denied setting the fires, but for some it’s about money. Volunteer firefighters in particular “don’t make money unless things are burning,” said Fischer, the federal investigator, whose career has focused on wildland fires.

Another motive is thrill seeking or the chance to be a hero.

Young, trainee firefighters are often spun a vision of going out every day to “fight the beast,” Nordskog said. But firefighting in relatively fire-safe countries like the US can be much more mundane; it may be months before many see their first fire.

“Boredom causes a lot of problems in the firehouse,” Nordskog said. Although he stressed the roughly 100 firefighters arrested each year make up only a tiny sliver of the more than 1 million firefighters in the US.

Arson in a hotter world

Climate change is adding a new dimension to arson.

Wildfires are fueled by many factors but scientists say the climate crisis is loading the dice in favor of more frequent, intense fires and longer fire seasons.

Awareness of these increasingly dangerous fire conditions doesn’t appear to be inspiring arsonists, said Gianni Muschetto, staff chief at the California Department of Forestry and Fire Protection. “There’s not really any data to say during red flag conditions that we have an uptick in an arson fires,” he told CNN.

But it does affect arsonists’ ability to cause destruction.

As the world warms, “the risk of catastrophic outcomes is arguably heightened,” the forensic psychologist Tyler said. Not everyone sets a fire to cause harm but weather conditions can whip a small fire into a deadly blaze.

A man was arrested last July for arson after allegedly starting California’s Park Fire by pushing a burning car down a 60-foot embankment, a charge he denies. It happened as an extreme heat wave parched the land, and the fire became one of the largest in California’s history, burning through an area bigger than Houston.

This is “the scary part,” Muschetto said. “If they light that fire, regardless of their intent, they have no control of how big it gets.”