Humans sparked 84 percent of US wildfires, increased fire season over two decades

How should we deal with the new math on forest fires?

If this article published in the February Proceedings of the National Academy of Sciences is not a fluke then it would seem to me that our expanding population dictates the need for more forest management not less. The less desireable alternative would be to severely restrict access to our federal forests. The main conclusion of the article is that humans sparked 84 percent of US wildfires and caused nearly half of the acreage lost to wildfire. This number excludes intentionally set controlled burns.

From the above, I would deduce that human initiated fires caused proportionally less acreage loss because they were closer to civilization and to forest access points and therefore closer to and more easily accessed by suppression resources. The fact that nearly half of the wildfire acres lost occur in these areas suggests that we would get more bang for our tax dollars if we increased and focused federal sustainable forest management around high traffic areas easily accessible to humans.

Knowing that humans who cause wildfires are, by definition, either careless or malicious, we might deduce that they are generally not inclined to put great effort into getting to their ignition set points. This would lead us to consider that human caused fires might prove to be in less difficult terrain areas with high human traffic. Fires like the Rim fire being the exception. That, if true, would suggest that forest management for risk reduction on these sites could be done at lower costs per acre than other less accessible forest acreage. Focusing forest management efforts on these high benefit to cost areas would have the biggest bang per tax dollar expended in order to lower the total cost of federal wildfire control. If my thinking is correct, this should play a large part in setting the priorities as to where we should: 1) apply controlled burns to reduce ground and other low fuels, 2) utilize commercial thinnings to reduce ladder and proximity fuels or 3) use commercial regeneration harvests to create greater variation in tree heights between stands in order to provide fire breaks for crown fires when appropriate for the site and species. The net effect would be positive for all species including endangered and threatened species. There would still be plenty of lightning caused wildfire, controlled burn hotspots/breakouts and a significantly reduced acreage of human caused fires to satisfy those who don’t mind national ashtrays. Reducing the number and size of human caused fires would also free resources to attack lightning fires earlier and harder when allowing the fire to burn was not an option.

Pertinent Quotes:

  1. “After analyzing two decades’ worth of U.S. government agency wildfire records spanning 1992-2012, the researchers found that human-ignited wildfires accounted for 84 percent of all wildfires, tripling the length of the average fire season and accounting for nearly half of the total acreage burned.” Italics added
  2. “”These findings do not discount the ongoing role of climate change, but instead suggest we should be most concerned about where it overlaps with human impact,” said Balch. “Climate change is making our fields, forests and grasslands drier and hotter for longer periods, creating a greater window of opportunity for human-related ignitions to start wildfires.”” Italics added
  3. “”Not all fire is bad, but humans are intentionally and unintentionally adding ignitions to the landscape in areas and seasons when natural ignitions are sparse,” … “We can’t easily control how dry fuels get, or lightning, but we do have some control over human started ignitions.””

14 thoughts on “Humans sparked 84 percent of US wildfires, increased fire season over two decades”

  1. Yep, it would be nice if we had forests that survived human-caused wildfires. Sadly, some people do not factor in human impacts and issues into forest management. We can plan for the inevitable droughts, bark beetle blooms and firestorms….. or not.

  2. Quote from Gil’s third bullett point: ”Not all fire is bad, but humans are intentionally and unintentionally adding ignitions to the landscape in areas and seasons when natural ignitions are sparse,” … “We can’t easily control how dry fuels get, or lightning, but we do have some control over human started ignitions.”

    I lived up in the San Jacinto Mountains for almost 20+ years. I lived in the large valley community of Anza. It was common for people to strip their land of native vegetation to bare soil and keep it maintained that way. The problem was that Nature is programmed to cover the land and unfortunately instead of more natives, they get invasive Mediterranean species of various grasses and other weeds. Fires happened all the time on those properties and then proceed to move into the surrounding National Forest areas. Common human stupidity caused fires were people who had horses and would pile massive amounts of manure out away from the house, barn, corrals and other outbuildings and into open dry grassy fields. On a numer of occasions I personally stopped by properties on the valley floor at the foot of my home on Table Mountain and grabbed hoses to put out smoldering and often burning manure piles with six inch to a foot tall small flames which would have been a wildfire had I not seen them. The prevailing wind from the west would have carried a wildfire towards my house. The posh equestrian ranchette homeowners were totally oblivious that such a thing could happen when I brought the fire to their attention.

    The other common fire starting scenario were these weekend Joe Six-Pack idiots who thought they could building and innovate anything and would be welding parts of something (tractors, trailers, etc) next to a stand of dry cheatgrass. The idiocy was incredible. Two of the worst historical damaging and forest costly fires ever came from Santa Rosa Indian Reservation where they have an open trash or rubbish slide down the side of this one canyon. Because it’s a Rez, nobody can say or do anything about it. This decades old trash slide continually smolders with smoke. The real problem is when the season of intense Santa Ana Winds kicks up with 60, 70 mile per hour gusts or even full blown hurricane 100+ force winds. You have to understand this is high elevation and winds are worse than along the interior valleys and cost of SoCal. The earliest fire took out major forests back in 1920 and came from the Santa Rosa Rez. The second in 1948 destroyed what grew back from the 1922 natural recovery. It never came back as forest trees ever again. It too came from the Santa Rosa Rez. The forest age didn’t heal back enough from the previous earlier 1920 fire to reproduce to mature cones in many cases. Aside from Chaparral, most trees that came back were some large oaks and mostly scrub oaks which were mainly resprouts from the ground. The natives (Indians) can burn chaparral anytime without a permit, but those on the outside cannot. Even when we would get a permit, it could only be used for “Russian Thistle” (Tumbleweeds). But stupidity has always reigned supreme out there. Mainly it’s always been those tiny weekend landowners who want a slice of weekend of summer holiday vacation.

    Other problems were the land speculation idiots would buy up chunks of large tracts and split them (after zoning changes) into 2 1/2 acres plots. These guys did a rough shod job and created terrible roads to make a quick buck off sales. Many times in developing these large land tracts their own irresponsble and inexperienced crews would start fires with machinery. Very little was ever said about this over the years, but I can tell you this stupidity and carelessness is a real problem.

  3. I wonder how much fire hazard is increased by expanded human access caused by fuel reduction logging and associated roads.

    • 2ndLaw

      I believe that the number of arsonists and recreationists does not decrease or increase depending on new logging sites or access roads. They will set their fires at the most convenient place possible. Consider that a favorite trick of arsonists is to flick a series of lit cigarettes out the car/truck window with a wooden match in the but. Consider the recreationist city slicker who is used to throwing his cigarettes on the ground without fully extinguishing them and without thinking sets a forest fire by flicking a lit cigarette out of the car/truck window or doesn’t put his campfire out cold and wet. They are going to be in the woods one way or the other and yes they might use a new road but new road or not they are going to set a fire. As to fuel reduction projects or commercial logging sites, the arsonists know enough to pick the places where they can make a quick getaway and their fire has the best chance of breaking out fast and carrying far. So they won’t be using sites where preventative practices have been carried out and their chance of success is low. As for the careless camper, better that he use an area where preventative practices have been carried out and there is less chance of him causing a catastrophic fire.

      Loggers can be careless just like any other group but their livelihood depends on not burning up the logs (stumpage) that they have paid for or not burning up the timber for which they have a cut and haul contract to deliver to a mill. In my experience, logging crew members watch out for each other because of all the ways that they will lose money and go out of business from accidentally starting a wildfire. In addition to the losses mentioned above, they will loose very expensive equipment that they probably still owe money on, they will probably get sued and their carelessness will cause landowners to not allow them to work on the landowner’s land. In addition, they will quite probably be in on the very unpleasant task of fighting the fire.

      So my money is on the arsonists who sticks to the roads for quick getaway and careless recreational users and the road and trail network that they use. So, like my opening comments at the top of this discussion thread suggest, that makes it all the more important that sound forest management which also lowers risk of catastrophic loss should be prioritized to focus on high traffic areas close to access. The actions of arsonists and careless recreational users always result in a net loss of forest acres to fire. On the other hand, the small loss of acreage due to forest management practices that went awry are more than offset by the acreage that wasn’t lost because of sound forest management preventative practices focused on risk reduction. Using marketable thinning and regeneration harvests rather than non-saleable fuel reduction projects (which is not logging but piling and burning) would also significantly reduce the risk of loss in my humble opinion. I also believe that the occasional control burn that gets out of hand poses a more serious threat than logging but they still do more good than harm. Letting existing fires run instead of suppressing them concerns me more than any other preventative practice because they are opportunistic rather than planned and decisions have to be made quickly without any of the preparation and controls that are ready in a control burn (equipment and people in place at key points to suppress if necessary) especially helpful is controlling the ignition points and time of ignition in accordance with weather forecasts and fuel moisture levels.

    • With fewer loggers in the woods, just WHO do you think goes out in the woods more, causing more wildfires? We’re tired of the “humans are a cancer upon the Earth” belief, pervasive within the ranks of the preservationists. Do you have a link to how many new USFS roads have been created, through fuels reduction projects, in the last 15 years? (I didn’t think so!) How many of those new roads have had new ignitions on them?

  4. What I see absent in the study summary & in the comments is any distinction of location of wildfires. Before we start recommending prescriptions, road access, etc. on Federal forest lands, perhaps we need to segregate the statistics of Federal forest land wildfires from all wildfires. Is that data buried in the report or is it ignored?

    • Thanks – This is a Great Opportunity for a Grad Student! Lat/lons are all there – just overlay transportation and trails network and get proximity of each ignition point to network by cause of ignition and then calculate distribution of acres burned by proximity class.

      My deductions/theories throughout this post are drawn from my experience – But, whether I am right or wrong, this database has the opportunity to give the feds sound information which can be used to prioritize forest management efforts to significantly reduce wildfire spread from malicious and careless human ignitions. It also has the opportunity to confirm or reject my long held belief that acreage lost to wildfires is proportionally greater on public lands than on well managed private lands thereby making an even stronger case for increased use of sound, sustainable forest management practices in accordance with the law and best management practices on federal lands. Unlike some people, I want the facts whether they support my beliefs or not. Unlike some, I am willing to be proven wrong because I want what is best for our forests not for my sense of power, ego, pride or for personal gain from lawsuits that exploit laws based on politics rather than established science or large salaries from increased member dues income by appealing to emotions rather than sticking to science.

      • The argument that private timber lands burn less because they are managed is a hard one to make. For profit timber companies aren’t buying marginal dry lands that are at the highest risk of fire because they aren’t great at growing trees. High site class productive ground that has 100+ year fire return intervals is much better at growing 2x4s. I think if you normalized for environmental factors burn probabilities would be the same.

        Anyhow, the database is a great resource. I remember an old forester once told me how he thought human ignitions in the North East dropped off significantly when folks started smoking coverages instead of pipes. Pipe tobacco when emptied provides a concentrated heat source more likely to start a fire than a moving cigarette flame.

  5. I think you would fine that the U.S. Forest Service burns up more forests than anyone. Loggers are required to have all kinds of fire fighting equipment on hand. The last thing they want is a fire. Maybe if you had more loggers working in the forests you could have a faster first response to these fires.

    • Re: “Maybe if you had more loggers working in the forests you could have a faster first response to these fires.”

      Anecdotal evidence from the past supports your theory especially when the greater abundance of logging roads in those days served as firebreaks and provided better access for fire suppression. Back in those days, when the woods caught fire, everyone nearby shut down their logging jobs and went directly to fight the fire in order stop the fire before it took off so as to preserve the woods that they loved, recreated in, and earned their livelihood from.

  6. Without even looking at the final results and costs, some people welcome ‘natural’ ignitions while blasting human-caused wildfires. Resilience through active management is something that those same people discount as undesirable, while, at the same time, embracing intense wildfires and their extreme effects and impacts.


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