Sawmill Fire: Wildfire a hot topic for UA experts
Mike Trubman, left, works with fellow Black Mesa Type-1 Interagency Hotshot Crew member Steve Daly, right, to mop up hot spots along Cienega Creek east of Empire Ranch while the Sawmill Fire burns on April 27, 2017, burning in Southeastern Arizona between Green Valley and J-6.
A wildfire sparked in the Santa Rita Mountains Sunday and is currently sweeping across the Coronado National Forest. It has already claimed over 40,000 acres of mesquite, oak and riparian woodland, according to reports from the Arizona Department of Forestry and Fire Management.
The Sawmill Fire was caused by humans, though the exact details are currently under investigation, according to Tiffany Davila, public affairs officer for the Department of Forestry and Fire Management.
Some of the factors contributing to the severity of the Sawmill Fire have been the extremely hot temperatures and high winds, direct results of current climate change, said Donald Falk, an associate professor in natural resources, global change and dendrochronology.
“The weather has played the main role in this fire; the wind has been fanning the flames; the fuels on the ground are dry, so those two combinations are hazardous conditions for firefighters,” Davila said.
According to Falk, increasing temperatures due to global climate change have resulted in fire seasons that start sooner and last longer.
“It used to be that fire season was about five months long, usually beginning in April or May, and now in the Southwest, fire season is almost 12 months, almost year-round,” Falk said.
This issue has recently received national attention, even before the Sawmill Fire. This month, Falk traveled to Washington D.C. to present on wildland fire issues at a congressional briefing sponsored by the University Corporation for Atmospheric Research.
Falk testified to members of congressional staff regarding the future of wildland fires and how current trends in climate and suppression tactics may impact the frequency and severity of these fires.
According to Falk, extreme fire behavior results from three main factors: topography, weather and fuel. These three factors make up what is called the fire behavior triangle and can be the cause of an extreme, fast-moving fire with a high heat output.
While topography is relatively fixed and doesn’t necessarily allow for much human modification, climate and fuel are a different story, Falk said.
Over an extended period of time, hot, dry, windy afternoons create the perfect fire weather, he added. Changes in climate have caused the range of weather to shift closer to the spectrum of extreme fire danger.
Recent data published by the USA National Phenology Network shows that spring is occurring three weeks earlier in the southeastern United States than it has in the past three decades.
Falk said this means that fires can now start three weeks earlier.
“Every degree of [temperature increase] means spring is going to come earlier, snowpack will melt sooner, the fuels will dry out and you will have a longer fire season,” Falk said. “When we project that out, it looks like fire season is just getting longer and longer and the peak intensity of temperatures is higher.”
The second factor—fuel—refers to the vegetation available to be consumed by fire.
Fire suppression and preventing natural fires leads to fuel build-up, which in turn results in extreme, out-of-control fire events, Falk said. When forests aren’t able to burn naturally, dead leaves and branches pile up, providing fires with access to the tree canopy.
One major source of fire suppression comes from federal- and state-sponsored fire management, said Jesse Minor, a graduate student studying geography and natural resources.
Where a forest might have normally burned every 12 years, suppression tactics have prevented the forest from burning for extended periods of time, resulting in missed fire cycles, Minor said.
“Eventually, you’ve got 100 years worth of fuel accumulated, where in the past, you would’ve only had five,” Falk said.
This means that when a fire is finally started, it can quickly get out of control, like the fire currently tearing through the Coronado National Forest.
According to Falk, in the case of the Sawmill Fire, dry vegetation build-up could have led to a more extreme blaze, while prior to fire suppression practices, it might have been a more manageable and beneficial fire.
“What we’re seeing now is fires that can’t be suppressed very easily, and they end up really radically changing the vegetation that we have out there in the mountains,” Minor explained.
And while Tucson’s inner-city neighborhoods probably won’t have to worry about wildland fires anytime soon, the surrounding mountains and Sonoran Desert are at risk.
The foothills and surrounding mountains are in greater danger of an extreme wildland fire.
“When you have a mixed fuel complex where you have houses and powerlines and gas lines and dense vegetation, all of that mixed together is a really hazardous condition,” Minor said.
According to Falk, one of the best ways to prevent extreme wildland fires is to simply let the fire run its course.
“You have to start letting fires burn again,” Falk said. “The bottom line is that fire, when it’s in its natural role, can safely reduce fuels over very large areas, entire landscapes, without you having to go out and do anything except protect people’s houses.”
Alternative ways of managing fire include using mechanical methods, such as thinning out trees or repurposing excess fuel into wood chips to allow for a safer, prescribed burn, Falk said.
“Fuel [treatment] is what we can do now and we can do it immediately, and it’s expensive, but a lot of things are expensive that are worth doing,” Falk added.
The Forest Service recently released a report stating they plan to use over two-thirds of their budget to focus on fire management and suppression in the next eight years.
The report stated the majority of the funds would go to “battling ever-increasing fires, while mission-critical programs that can help prevent fires in the first place […] will continue to suffer.”
There are currently over 600 people working to fight the Sawmill Fire, including a mixture of helicopters and airplanes and crews from across the state. Nearly 200 people have either been evacuated or face the possibility of having to evacuate their homes, Davila said.
Despite this, Falk and Minor remain optimistic.
The rise in extreme wildland fires is “absolutely treatable,” as long as prescribed burns are allowed and measures are taken to slow down climate change, Falk said.
To see the latest update on the Sawmill Fire, visit the National Wildfire Coordinating Group page here.
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