Researchers attempt to quantify how climate change will affect wildfire seasons

Future Very Large Fires wildfires

The projected percentage increase in the number of “very large fire weeks”—weeks in which conditions are favorable to the occurrence of very large fires—by mid-century (2041-2070) compared to the recent past (1971-2000). (NOAA)

Researchers are predicting that beginning 26 years from now the number of weeks in which very large fires could occur will increase by 400 to 600 percent in portions of the northern great plains and the Northwest. Many other areas in the West will see a 50 to 400 percent increase.

If they are correct, the effects of climate change are not generations away. Firefighters starting out today will be dealing with this on a large scale during their careers.

Warming due to increasing greenhouse gas emissions will likely increase the potential for ‘very large fires’—the top 10 percent of fires, which account for a majority of burned areas in many regions of the United States. Climate change is expected to both intensify fire-friendly weather conditions, as well as lengthen the season during which very large fires tend to spread.

The potential for very large fire events is also expected to increase along the southern coastline and in the forests around the Great Lakes, although the number of events along the northern tier of the country should only increase moderately given the historically low potential for these events.

For this study, researchers considered the average results of 17 climate model simulations to examine how the potential for very large fires is expected to change. Future projections* were based on a higher-emissions scenario called RCP 8.5, which assumes continued increases in carbon dioxide emissions.

Along with the elevated potential for very large fires across the western US in future decades, other climate modeling studies have projected increases in fire danger and temperature, and decreased precipitation and relative humidity during the fire season. The increased potential for these extreme events is also consistent with an observed increase in the number of very large fires in recent decades.

In addition, scientists have detected trends toward overall warming, more frequent heat waves, and diminished soil moisture during the dry season. The combination of these climate conditions and historic fire suppression practices that have led to the build-up of flammable debris have likely led to more frequent large fire events.

At this very moment, more than 56 large wildfires are burning uncontained throughout the West, putting homes, lives, and livelihoods at risk. The smoke created by these fires exacerbates chronic heart and lung diseases while also degrading visibility and altering snowmelt, precipitation patterns, water quality, and soil properties. In addition to public health impacts, projected trends in extreme fire events have important implications for terrestrial carbon emissions and ecosystems.

The authors of the study also note that these findings could place a burden on national and regional resources for fighting fires. Fire suppression costs in the U.S. have more than doubled in recent decades, exceeding $1 billion per year since the year 2000, the National Interagency Fire Center reports. The vast majority of that money is spent on large incidents.

climate change predicted fire seasons

The research was conducted by government employees at taxpayer expense, funded by NOAA, the U.S. Forest Service, and two universities. The authors were: Barbero, R.; Abatzoglou, J.T.; Larkin, N.K.; Kolden, C.A.; and Stocks, B. The title: “Climate change presents increased potential for very large fires in the contiguous United States”. It was published in Australia in the International Journal of Wildland Fire (copies available for $25).

We checked with which posts copies of government-funded research, and were told by Michael Tjoelker, “Unfortunately, due to copyright issues we are not able to distribute full text versions of Journal articles.” However, Renaud Barbero, one of the authors, sent us a copy.

Thanks and a tip of the hat go out to Bill.

Short film, “Unacceptable Risk: Firefighters on the Front Lines of Climate Change”

In February we showed you a trailer for a short film made by The Story Group that premiered later that month, titled Unacceptable Risk: Firefighters on the Front Lines of Climate Change. Now the entire 12-minute film is available — above.

Here is the description of the film on Vimeo:

…The Story Group [based in Boulder, Colorado] recorded the experiences of firefighters who are repeatedly responding to record-breaking wildfires. Human-caused climate changes are transforming Colorado’s fire environment, bringing higher temperatures, drier fuels, and diseases to forests. These climate impacts mix with other human pressures to create a volatile situation for firefighters and communities. If current trends continue, we can expect more frequent, larger, and more devastating wildfires in Colorado and across the country.

It is really an excellent film. A great deal of information is packed into 12 minutes. What makes it special are the interviews with experienced firefighters who all testify to seeing fire behavior in the last decade or so that to their knowledge is unprecedented, at least in the front range of Colorado. The firefighters interviewed are all very well spoken and have something worthwhile to say.

They include Don Whittemore, an Incident Commander and a firefighter for 22 years; Chris O’Brien, Deputy Chief of the Lefthand Fire Protection District; Rod Moraga, Fire Behavior Analyst, firefighter for 28 years; and James Schanel, Battalion Chief, Colorado Springs Fire Department, firefighter for 30 years.

At the end they make a pitch about climate change, emphasizing how important it is to mitigate it NOW. And they are absolutely right. But there is a strong message for firefighters who are being forced to deal with a new normal. Mr. Whittemore said:

On a day to day basis we’re being surprised. And in this business, surprise is what kills people.

The visuals of wildfire are impressive — the videos, photographs, and time-lapse images.

The film can also be seen on Rocky Mountain PBS television. We can’t embed it here, but that version also includes interviews (beginning at 13:00) with Mr. Moraga and filmmaker Daniel Glick.

We received the following from Ted Wood of The Story Group, an Executive Producer and Camera Operator on the film:

The Story Group is funded entirely through grants and donations, and we’re trying to recoup some of our distribution costs by pointing people to our pay-per-download Vimeo site, where people who want to use the film for fire presentations, workshops, etc can pay $9.95 and download it. We’ve had a real interest from Colorado fire managers to use the film in training, and we’d like to offer it to a larger national audience.

Vegetation fires affect snow melt

Wildfire, climate change and declining snowpacks are intricately connected. As temperatures rise, moisture-stressed forests can lead to bigger, hotter, longer and more frequent wildfires. In turn, wildfires can impact the amount and timing of snowmelt runoff according to a study by Anne Nolin and her Ph.D. student Kelly Gleason. The two researchers have presented new evidence showing that particles and burned woody debris from charred forests increase snowmelt and impact the hydrologic cycle — illustrated in this animation.

A film: “The Fire Next Time”

The producer describes this film:


“In this 13-minute film, filmmakers Stephen Most and Kevin White examine how problematic policies, fuel build-up, and climate change have endangered America’s forests. When the Rim Fire burned 256,000 acres of the Stanislaus National Forest and Yosemite National Park in 2013, it exposed the impacts that high intensity wildfires are having on watersheds, wildlife, and carbon storage. It also forged a coalition of environmentalists, loggers, scientists, officials, and land managers who are responding to this megafire and recognize the need to forestall the next one. “The Fire Next Time” is a precursor to Filmmakers Collaborative’s feaure-length work-in-progress, “MEGAFIRE at the Rim of the World.” For more information, visit”

More science indicates pine beetle outbreaks do not lead to catastrophic fire

mountain pine beetle

Mountain pine beetle

Scientists continue to develop evidence showing that pine beetle outbreaks do not lead to catastrophic wildfires. This should not be a shocking development to those who have been keeping abreast of the studies on the subject, including one that Wildfire Today first covered in 2010 (Firefighters should calm down about beetle-killed forests).

In a soon to be published paper, University of Colorado Boulder researcher Sarah Hart determined, “The bottom line is that forests infested by the mountain pine beetle are not more likely to burn at a regional scale. We found that alterations in the forest infested by the mountain pine beetle are not as important in fires as overriding drivers like climate and topography.”

The CU-Boulder study authors looked at the three peak years of Western wildfires since 2002, using maps produced by federal land management agencies. The researchers superimposed maps of areas burned in the West in 2006, 2007 and 2012 on maps of areas identified as infested by mountain pine beetles.

Western U.S. forests killed by the mountain pine beetle epidemic are no more at risk to burn than healthy Western forests, she found. Results that fly in the face of both public perception and policy.

The area of forests burned during those three years combined were responsible for 46 percent of the total area burned in the West from 2002 to 2013.

Co-authors on the new study include CU-Boulder Research Scientist Tania Schoennagel of the Institute of Arctic and Alpine Research, CU-Boulder geography Professor Thomas Veblen and CU-Boulder doctoral student Teresa Chapman.

Sarah Hart CU Boulder

Sarah Hart

The impetus for the study was in part the severe and extensive native bark beetle outbreaks in response to warming temperatures and drought over the past 15 years that have caused dramatic tree mortality from Alaska to the American Southwest, said Hart. Mountain pine beetles killed more than 24,700 square miles of forest across the Western U.S. in that time period, an area nearly as large as Lake Superior.

“The question was still out there about whether bark beetle outbreaks really have affected subsequent fires,” Hart said. “We wanted to take a broad-scale, top-down approach and look at all of the fires across the Western U.S. and see the emergent effects of bark beetle kill on fires.”

Previous studies examining the effect of bark beetles on wildfire activity have been much smaller in scale, assessing the impact of the insects on one or only a few fires, said Hart. This is the first study to look at trends from multiple years across the entire Western U.S. While several of the small studies indicated bark beetle activity was not a significant factor, some computer modeling studies conclude the opposite.

The CU-Boulder team used ground, airplane and satellite data from the U.S. Forest Service and the U.S. Geological Survey to produce maps of both beetle infestation and the extent of wildfire burns across the West.

The two factors that appear to play the most important roles in larger Western forest fires include climate change — temperatures in the West have risen by about 2 degrees Fahrenheit since 1970 as a result of increasing greenhouse gases — and a prolonged Western drought, which has been ongoing since 2002.

“What we are seeing in this study is that at broad scales, fire does not necessarily follow mountain pine beetles,” said Schoennagel. “It’s well known, however, that fire does follow drought.”

The 2014 Farm Bill allocated $200 million to reduce the risk of insect outbreak, disease and subsequent wildfire across roughly 70,000 square miles of National Forest land in the West, said Hart. “We believe the government needs to be smart about how these funds are spent based on what the science is telling us,” she said. “If the money is spent on increasing the safety of firefighters, for example, or protecting homes at risk of burning from forest fires, we think that makes sense.”

Firefighting in forests that have been killed by mountain pine beetles will continue to be a big challenge, said Schoennagel. But thinning such forests in an attempt to mitigate the chance of burning is probably not an effective strategy.

“I think what is really powerful about our study is its broad scale,” said Hart. “It is pretty conclusive that we are not seeing an increase in areas burned even as we see an increase in the mountain pine beetle outbreaks,” she said.

“These results refute the assumption that increased bark beetle activity has increased area burned,” wrote the researchers in PNAS. “Therefore, policy discussions should focus on societal adaptation to the effect of the underlying drivers: warmer temperatures and increased drought.”

The entire paper can be downloaded (1MB).
Reports about other pine beetle studies, and general articles on the insects, are tagged beetles.