California’s longer, riskier fire seasons usher in new era for public safety and environment

Scientists are confirming what many Californians already suspect: The wildfire season is becoming longer and more intense as our climate becomes warmer and more volatile.

Human-driven climate change has doubled the cumulative acreage burned by forest fires since 1984, according to a 2016 report in the journal of the Proceedings of the National Academy of Sciences.

In California, the acreage that burns annually has increased 500% since 1972, according to a study published in July in Earth’s Future, a journal that examines global environmental trends.

The trend has led to a new trope: the year-round wildfire season. Throughout much of the West and particularly in California, the thinking goes, there is no longer a fire season sharply defined by the desiccating fuels of early summer and the first autumn rains. Instead, our wildlands can now burn at any time, expanding the season from six or seven months to 12.

Yet the true situation is more complicated than that. It now seems assured that the North Bay fires of 2017 and this year’s Kincade fire aren’t outliers. They’re more likely harbingers of what then-Gov. Jerry Brown last year called “the new abnormal,” an era marked by more fires, bigger fires and increased threats to human life and property.

But the risk isn’t distributed evenly, and wildfire researchers and firefighters alike say appropriate responses will very depending on the region, land-use practices and other factors.

Further, the public needs to distinguish between different uses of the term “fire season,” said Marshall Turbeville, a Cal Fire battalion chief and the chief of the Geyserville Fire Prevention District. The state defines the wildfire season in legal terms, using weather and fuel conditions as metrics, Turbeville said.

“The start and ending is determined each year by declarations from Cal Fire, and (for the 2019 season) it ended on Dec. 9,” said Turbeville. “But the larger issue is the wildland fire potential season, and that definitely seems to be getting longer. We’re now seeing large fires occurring from late summer through early December. I’ve had 24 years in firefighting, and when I started out as a seasonal employee we’d typically get hired in early June and laid off in the fall. Now Cal Fire is hiring seasonal firefighters as early as March 1, and in some cases they’re not being laid off.”

Several years ago, said Turbeville, “We’d be doing winter preparation tasks such as pile and broadcast burning in late October. But that’s now when we usually have our biggest fires. So the reality is that the wildfire potential season - the time when we can see really destructive wildfires - is about nine months.”

Scott Westrope, the deputy fire chief for the city of Santa Rosa, agrees with Turbeville that the de facto fire season is lengthening, a fact that compounds operational and administrative challenges for firefighters. Not long ago, said Westrope, firefighting agencies could expect a multiple-month break between seasons, allowing for such things as administrative review, gear inspection and repair.

“Preparation typically starts as soon as the heavy rains begin, but that timeline has become compressed,” said Westrope. “For Santa Rosa at least, the fire season is literally yearlong. If we’re not actually fighting fire all year, the following season could literally begin in a matter of weeks, meaning that active training and preparation never stops.”

While both coastal California and the Sierra Nevada are experiencing increased wildfire activity, their seasons aren’t necessarily congruent and fire causes are often different. The Sierra typically sees a shorter season than coastal California because fire danger drops abruptly with the first snowfall, while the threat can linger much longer in coastal regions. Still, the fire danger in the Sierra quickly ramps up once the snow melts and the sun starts beating down.

“It’s clear that the Sierra’s fire season is lengthening,” Carmen Tubbesing, a doctoral candidate in fire science at UC Berkeley’s Department of Environmental Science, Policy and Management. “We’re seeing more days per year of red-flag weather. The prolonged droughts associated with climate change are killing more trees and drying fuels to an increasing degree, generally compounding the threat.”

In the Sierra, lightning usually accounts for most of the ignitions, Tubbesing says, while coastal region wildfires are mainly attributed to human-associated causes - damaged power lines, cars, lawnmowers and arson. The Sierra has a bigger fuel problem - millions of drought-killed conifers - than the coastal regions, but the Bay Area and Southern California have a greater dilemma in the spread of development into wildland: that is, very large numbers of people living close to open space that contains enough trees, grass and brush to burn fiercely.

In both regions, Foehn winds - extremely powerful, hot, dry winds that blow from east to west - are major drivers of wildfire, particularly in autumn. In Northern California, they are known as Diablo winds; in Southern California they’re called Santa Ana winds.

The wind-fueled catastrophic blazes of the past years, meanwhile, have left a profoundly altered landscape throughout vast swaths of the state. In the Sierra, says Tubbesing, large expanses of coniferous forest and mixed woodlands are at risk of shifting to brush lands.

“When that happens, a lot of ecological complexity is lost,” Tubbesing said. “The diversity of plant and animal species is greatly reduced.”

Likewise, the Tubbs and Kincade fires have left deep marks on eastern Sonoma County, including Pepperwood Preserve, the region’s largest wildland research center. The Tubbs fire burned through most of the preserve in 2017, immolating stands of highly flammable Douglas fir. That blaze alone seemed likely to shift much of the property from conifers toward oak woodlands and grasslands - not necessarily an undesirable change, given that the rigorous suppression of wildfires over the past century has led to an “unnatural” preponderance of Douglas fir over oaks in many areas.

But the Kincade fire followed hot on the heels of the Tubbs fire. It scorched about 60% of Pepperwood - including some areas that haven’t burned in decades, such as heavily forested Garrison Canyon. Further, Pepperwood served as a staging area for firefighters battling the Kincade blaze.

“We had 1,500 firefighters, seven bulldozers and a lot of fire engines and other vehicles up here,” said Tosha Comendant, the conservation science manager for Pepperwood. “They ensured our safety - we didn’t lose a single building - and it was a privilege to have them here. But the preserve now has 25 miles of dozer lines that were cut as part of the suppression efforts, and we have to re-grade and seed them to prevent erosion. Our roads were also chewed up by the heavy equipment, and we have to repair them. It’s an extremely expensive and challenging process, and it points to a larger question: How can communities meet the dual role of fire mitigation and suppression on one hand and ecosystem preservation on the other?”

In terms of response, much already is being done locally, said Spencer Andreis, the operations battalion chief for the Sonoma Valley Fire & Rescue Authority. The Tubbs fire was a wake-up call for both residents and emergency response agencies, Andreis said, and lessons learned during that blaze were applied when the Kincade fire broke out.

“The Kincade fire was essentially a predicted event and we were ready for it,” said Andreis. “We knew that strong winds were coming, and we prepositioned equipment and firefighters in preparation. That ensured we had what we needed not just at the start of the fire, but through the entire extreme-weather period. We had a comprehensive, large-scale notification and evacuation process, and we were able to get people out so firefighters could concentrate on their work. And as a general strategy, it all made a huge difference. No one died during the Kincade fire and we prevented it from crossing to the west side of Highway 101.”

Long-term wildfire planning also requires landscape-scale fuel management, say experts. Wherever possible, that means re-introducing fire into wildlands. In Yosemite National Park, a “let it burn” policy has returned large areas to a more natural, fire-resistant landscape, one characterized by larger, well-spaced trees, diverse niche ecosystems and a resurgence in native plants and animals. But such a policy is difficult to implement in locales such as Sonoma County, where open space and expansive developed areas adjoin each other. Here, small controlled burns, mechanical thinning and rigorous enforcement of residential defensible space requirements are the primary options.

“If there’s one thing that’s missing in wildfire news coverage, I think it’s acknowledgment of the nuances of fuels management,” said Zack Steel, a postdoctoral researcher at UC Berkeley’s Stephens Lab, an investigatory center for wildland fire science. “Different parts of the state - and the different habitats within those areas - are likely to require varying approaches. There’s no single ‘best’ approach.”

In any case, it’s clear that the “new abnormal” will require expanded funding for fire response and fuels management - and securing money for all that extra work is proving a challenge.

“We’re using more equipment, we’re working people harder, and we’re currently understaffed,” said Westrope, the Santa Rosa fire deputy chief. “It’s pretty explicit that we need to hire more people in operations, prevention and administration. Our call volume is going up at 3% a year - we’ve topped 30,000 calls this year alone. For the size of this city, for the inherent risks, we’re not near where we need to be in terms of staffing.”