Overwhelming Cause of California Wildfires: Humans


As blazes continue around San Diego, can humans do more to prevent future fires?

Investigators around San Diego continue searching for the causes of ten fires that burned thousands of acres of land in the area this week, after determining that one of the blazes was set by sparks from construction equipment.

Whether the other blazes were set intentionally or by accident, experts say it's highly likely that humans are to blame. Two people were arrested north of San Diego on Thursday on suspicion of arson, though it's not clear if they are thought to be connected to this week's big fires.

Unlike remote parts of the world where natural events like lightning strikes are prime sources of wildfires, in southern California, such fires are almost always started by people. Ninety-five percent have a human cause, according to Cal Fire, the state's firefighting agency.

The situation may worsen in the face of expected population growth. Metropolitan San Diego's population is expected to reach nearly 4.5 million by 2050, over a million more than today. (Pictures: San Diego Wildfires)

"The probability of fires is increasing because people are increasing," said the U.S. Geological Survey's Jon Keeley, who has spent years studying the history of California wildfires.

The Wildest Things

Most of the big Southern California wildfires of recent years were found to have human causes.

In 2007 a fallen power line near San Diego set off a fire that scorched nearly 200,000 acres and killed two people.

In 2009, sparks from a weed cutter are thought to have led to an 8,700 acre fire in Santa Barbara County that torched 80 homes.

And earlier this month, an illegal campfire started in Rancho Cucamonga grew to 2,700 acres.

Other area fires have been blamed on chains dragging behind cars and throwing off sparks, smoldering cigarette butts, welding tools, errant gunfire, and arsonists.

"It's anything you could possibly think of," said Alexandra Syphard, a San Diego scientist at the non-profit Conservation Biology Institute who has combed through thousands of California wildfire reports to understand what's causing the fires. "You see the wildest things. One of them was a satanic ritual."

A more common culprit: outdoor equipment, from power saws to lawnmowers. Power tools accounted for more than 20 percent of fires in San Diego County between 2000 and 2010. That was followed by fires caused by campfires (nearly 10 percent), arson (roughly 5 percent), trash burning (around 4 percent), vehicles doing things like sending out sparks or igniting vegetation with overheated tailpipes, downed or malfunctioning power lines, kids playing with fire, and cigarettes.

Blackouts and Leapfrog Housing

Some fire experts see a silver lining to these dreary statistics: If people are mostly to blame for wildfires, they can do something about it.

"Weather doesn't cause fires–weather just causes a fire to burn," said Cal Fire spokesman Daniel Berlant. "It's the people that have the role of actually preventing that fire."

His agency, along with the U.S. Forest Service, the National Park Service and other land managers that deal with wildfires, is leading a public relations campaign urging Californians to reform outdoor habits.

Written By: Warren Cornwall
continue to source article at news.nationalgeographic.com


  1. Its just going to get worse. The insurance companies will catch on and the rates will skyrocket. Of course there is no global warming so don’t be alarmed…………

  2. Perhaps they are missing the point that wild fires are natural in dry areas, and that preventing them in the short-term, means that dry inflammable material builds up on the ground, to provide fuel for a bigger fire later.

    Fire ecology is concerned with the processes linking the natural incidence of fire in an ecosystem and the ecological effects of this fire. Many ecosystems, particularly prairie, savanna, chaparral and conifer forests, have evolved with fire as a necessary contributor to habitat vitality and renewal. Many plant species in naturally fire-affected environments require fire to germinate, establish, or to reproduce. Fire suppression not only eliminates these species, but also the animals that depend upon them. Finally, fire suppression can lead to the build-up of flammable debris and the creation of less frequent but much larger and more destructive wildfires.

    Campaigns in the United States have historically molded public opinion to believe that wildfires are always harmful to nature. This view is based on the outdated belief that ecosystems progress toward an equilibrium and that any disturbance, such as fire, disrupts the harmony of nature.

    So.. ….. Humans are not only sparking off the fires, but are probably causing the build-up of inflammable debris, as dry dead material builds up, year on year in areas naturally prone to cyclical fires in the vegetation.

    Fire suppression, in combination with other human-caused environmental changes, has resulted in unforeseen consequences for natural ecosystems. Some uncharacteristically large wildfires in the United States have been caused as a consequence of years of fire suppression and the continuing expansion of people into fire-adapted ecosystems.

  3. Even up here in less densely populated Washington state, most of the recent huge wildfires (in the arid eastern part of the state) have been set by humans. One a couple of years ago was started by a spark from a welder’s torch as workers repaired a bridge. That fire burned dozens of homes and cabins, miles of wilderness, and closed two major highways for weeks. Others have been started by assholes who throw cigarettes out of their cars – I’ve seen them do it. Or morons that decide to barbecue half a cow over a raging bonfire on a hot, windy day in August. Or people who drive a car down an overgrown road and the hot undercarriage starts the grass on fire. You name it, people do it – and few things are scarier and harder to escape than a raging wildfire. In 1988 I was almost trapped near West Yellowstone as the huge fire that ravaged Yellowstone park suddenly surged toward the town and cut off the road. It took driving nearly 70 mph on a narrow mountain road, surrounded by flaming trees, black smoke, and blowing cinders, to get away (barely). Since then I have a healthy respect for (or maybe more like a morbid fear of) fire.

Leave a Reply