Is climate change the culprit causing California’s wildfires?

Summary: We’re told that climate change caused or intensified California’s wildfires — and that such fires are getting worse. As usual for such scary stories, these claims are only weakly supported by science — except for the ones that are outright fabrications. See what scientists say and decide for yourself.

“If we keep fighting a war with fire, three things are going to happen. We’re going to spend a lot of money, we’re going to take a lot of casualties, and we’re going to lose.”

— Stephen Pyne, professor at Arizona State University (source: National Geographic).

Wildfire Earth

(1)  Those California Wildfires!

“Gov. Jerry Brown surveyed the devastation Saturday in Ventura …calling it ‘the new normal.’ …“This could be something that happens every year or every few years.’” {Source: LAT.}

Climate change is causing more wildfires! Or so we are told. That is a zombie climate myths — repeatedly said, repeatedly debunked by scientists, but too useful to die. When Brown made this claim in 2015 even the LAT said that “Gov. Brown’s link between climate change and wildfires is unsupported, fire experts say.

“{C}limate scientists’ computer models show only that global warming will bring consistently hotter weather in future decades. Their predictions that warming will bring more forest fires — mostly in the Rockies and at other higher elevations, while fires may actually decrease in Southern California — also are for future decades. Even in a warmer world, they say, land management policies will have the greatest effect on the prevalence and intensity of fire. …

“‘There is insufficient data,’ said U.S. Forest Service ecologist Matt Jolly. His work shows that over the last 30 years, California has had an average of 18 additional days per year that are conducive to fire. …

“Today’s forest fires are indeed larger than those of the past, said National Park Service climate change scientist Patrick Gonzalez. At a symposium sponsored by Brown’s administration, Gonzalez presented research attributing that trend to policies of fighting the fires, which create thick underlayers of growth, rather than allowing them to burn. ‘We are living right now with a legacy of unnatural fire suppression of approximately a century,’ Gonzalez told attendees. …

“Fire behavior specialist Jeff Shelton, who provided daily forecasts for the Rocky fire and, later, the Jerusalem fire, said he could not attribute their behavior to climate change. He cited the summer’s dry weather, an abundance of fuel created by a lack of previous fires, and steep slopes that allowed the fires to spread quickly. Ecologists said their behavior was typical of natural chaparral fires, which burn infrequently but intensely. …

“‘They are more and more common because we have more and more fuels,’ said Joaquin Ramirez of Technosylva, an international fire modeling company based in San Diego. …

Bureau of Land Management fire manager Jeff Tunnell {said} ‘One hundred years of fire suppression is building fuel beds,’ Tunnell said. ‘Almost any year can produce a fire like this one.'”

The LAT has run a similar article about the 2017 fires: “Wind is the culprit in 2017’s horrific wildfire season” by Bettina Boxall.  For a detailed debunking of Governor Brown’s claim, see this typically excellent analysis by Cliff Mass: “Are California Coastal Wildfires Connected With Global Warming: The Evidence Says No.” He is a Professor of Atmospheric Science at U WA.

See the current national wildfire stats compared to those of recent years.

A world on fire

(2)  But US wildfires are getting worse! Unprecedented!

“These fires are unprecedented. We’ve never seen anything like it. ”
Governor Jerry Brown on “60 Minutes”. 10 December 2017.

Forest fires are a natural and inescapable part of our ecology, and in the past (the colder past) have occurred far more frequently than they do today. It’s nice to live in the now, but we cannot understand the world without knowledge of its past.

(a)  See the graph that must not be seen, so journalists never show it.

David B. South, Emeritus Professor, of Forestry at Auburn U, showed the long-term history of US forest fires in his Senate testimony on 3 June 2014 (page 2). Bjorn Lomborg posted an updated version of his graph, using the same sources. Click to enlarge graph. Excerpt…

“Fires in California and elsewhere are devastating. But US fires are nowhere near the record. More likely about one-fifth of the records in 1930 and 1931. Reuters (along with many others), tell us the current US fires are historic …

“Yet, the official historical data of the United States tells a different story. Look at the Historical Statistics of the United StatesColonial Times to 1970 (p537). There we have statistics for area burnt since 1926 and up to 1970. Reassuringly, the data for 1960-1970 *completely overlap* (that from the National Interagency Fire Center}. This is the same data series.

“And when you look at the whole data series, *every year* from 1926-1952 – over a quarter of a century – saw higher, and mostly much higher forest areas burnt than the modern record set in 2015.

“This is not (as some have suggested) an artifact of the US gradually being deforested (and hence having less land to burn). The USDA Forest Service in their Historical Overview (p7) finds that the US “forest area has been relatively stable since 1910” – if anything slightly increasing since 1910 (which would help push up the burnt area slightly).”

US acres burned 1926-2017

The steep decline in the 1930s results from the New Deal boosting the fire suppression programs of the National Parks and Forest Services, providing both money and manpower (from the Civilian Conservation Corps).

(b)  Incidence of wildfires in North America 1600-2000. they peaked in the mid-19th century.

That peak of fires in the early 20th century seems awesome — until you read “Multiscale perspectives of fire, climate and humans in western North America and the Jemez Mountains, USA” by Thomas W. Swetnam et al. in Phil Trans B, 5 June 2016. Fire incidenc peaked in the mid-19th century. Click to enlarge the graph.

“The combined record of fire occurrence from more than 800 sites in western North America shows relatively high fire frequency prior to ca 1900, and a high degree of synchrony in both large and small fire years. The 15 largest and smallest fire years are labelled. A pronounced decrease in fire frequency occurred at the time of Euro-American settlement, coinciding approximately with the arrival of railroads, intensive livestock grazing, removal of many Native American populations, and subsequently organized and mechanized fire fighting by government agencies.”

Wildfires in North America 1600-2000

(c) A smaller and more precise record: fires in Yosemite National Park. Area burned peaked in the early to mid-19th century.

Climatic and human influences on fire regimes in mixed conifer forests in Yosemite National Park, USA” by Alan H. Taylor and Andrew E. Scholl in Forest Ecology and Management, 1 March 2012 (gated). Different data, same pattern — a peak in the mid-19th century, followed by a long decline. Click to enlarge.

Wildfires in Yosemite National Park: 1600-2000.

Wildfires in Yosemite National Park 1600-2000

(3)  What about the rest of the world?

The rest of the world never shared our Smokey the Bear obsession about preventing forest fires.

(a)  For a short term perspective.

See “Global trends in wildfire and its impacts: perceptions versus realities in a changing world” by Stefan H. Doerr and Cristina Santín in Phil Trans B, 5 June 2016. Red emphasis added. This study shows that the total global area burned per year is less today than centuries ago — and the area has declined during the past few decades.

“Wildfire has been an important process affecting the Earth’s surface and atmosphere for over 350 million years and human societies have coexisted with fire since their emergence. Yet many consider wildfire as an accelerating problem, with widely held perceptions both in the media and scientific papers of increasing fire occurrence, severity and resulting losses.

“However, important exceptions aside, the quantitative evidence available does not support these perceived overall trends. Instead, global area burned appears to have overall declined over past decades, and there is increasing evidence that there is less fire in the global landscape today than centuries ago.

“Regarding fire severity, limited data are available. For the western USA, they indicate little change overall, and also that area burned at high severity has overall declined compared to pre-European settlement. Direct fatalities from fire and economic losses also show no clear trends over the past three decades. Trends in indirect impacts, such as health problems from smoke or disruption to social functioning, remain insufficiently quantified to be examined.

“Global predictions for increased fire under a warming climate highlight the already urgent need for a more sustainable coexistence with fire. The data evaluation presented here aims to contribute to this by reducing misconceptions and facilitating a more informed understanding of the realities of global fire.”

Wildfire occurrence (a) & area burnt (b) in the European Mediterranean region during 1980–2010.

Phil TransB - long-term trend in wildfires

Phil TransB - long-term trend in wildfires

(b) For a longer-term perspective.

See “Spatial and temporal patterns of global burned area in response to anthropogenic and environmental factors: Reconstructing global fire history for the 20th and early 21st centuries” by Jia Yang et al. in JGR – Biogeosciences, March 2014.  A similar result to the other studies: fires in the early 20th century burned a larger area of the world than they do today, with a declining trend since the 1940s.

Decadal variation of global burned area. Error bar refers to the standard deviation of annual burned area within that decade.

Global Area Burnt from Yang 2014

(4)  Essential reading to understand the origins of these fires

How Fire, Once a Friend of Forests, Became a Destroyer” by Michelle Nijhuis in National Geographic — “The roots of today’s massive wildfires, says historian and former firefighter Stephen Pyne, lie in the old misconception that all fire is bad.” Pyne is a professor at Arizona State University (see his website), studying the history of wildfire and wildland firefighting in the U.S. and the world. Here are two key points, looking at the results of a century of fire suppression in the US — and looking forward.

“There’s a huge cost to removing all fires from landscapes that have grown up accustomed to them. Fuels — dry wood, leaves, other materials — build up in the forest, and the whole ecological integrity of the system unravels. Simply trying to eliminate fire helps to promote conditions in most places that make for more severe fires with larger consequences and damages, making them more uncontrollable. It costs more and more money to try to keep a lid on the situation, so there’s an economic cost. There’s also a cost in lives — civilian lives, and firefighter lives. …

“Sustainability is an overused and sloppy term, but this is not a sustainable project. We cannot continue to do this. …

“We’re not helpless. We can keep these fires from burning prized assets if we wish. But I think managed wildfire is an acknowledgement that despite our bold talk, we’re not going to get ahead of the problem, and that we have to manage it. The climate, the fuels, the invasive species, the insect outbreaks, and whatever else is coming at us — there’s no way we’re going to get ahead of most of this stuff. We’re only going to do that very selectively.”

The LAT discusses how we got here and how to better cope in the future: “California’s deadliest wildfires were decades in the making. ‘We have forgotten what we need to do to prevent it’.

The same debate is taking place in Canada, with fires blamed on climate change, while most scientists disagree. Such as Blair King’s “We Can’t Blame Climate Change For The Fort McMurray Fires” at the HuffPost (he’s an environmental scientist) and “Science not there: global warming not fueling Alberta’s wildfire” by Thomas Richard at the Examiner.

Update: the NYT reviews two new books about wildfires, pointing to the obvious causes.

“As detailed in Michael Kodas’s bracing Megafire: The Race to Extinguish a Deadly Epidemic of Flame and Edward Struzik’s drier Firestorm: How Wildfire Will Shape Our Future, today’s forests are often clogged with desiccated vegetation because — unlike in countless millenniums past — they are seldom cleansed by naturally occurring blazes. With such an abundance of fuel to feast on, wildfires like those currently raging in California have become increasingly ruinous and intense.

“The bureaucrats and scientists who have tried to warn against the folly of treating every wildfire like a mortal foe have discovered their message is a nonstarter. That’s partly because so many businesses are keen to preserve the status quo: About 40% of America’s wildfire-fighting resources, from helicopters that can cost as much as $7,000 an hour to catering services that charge $100,000 a day, are now provided by private companies. ‘Most don’t get paid if they’re not actively fighting a fire,’ Kodas points out, ‘so they lobby to fight as many fires as they can.’ …

“But the most powerful constituency in favor of perpetuating the futile war on wildfires is the people who’ve chosen to inhabit risky terrain. According to a 2015 study, America’s 13 Western states contain 1.1 million homes deemed ‘highly vulnerable to wildfires’ because of their proximity to forests full of tinder. There is no easy way to convince the owners of those homes that a fire they can glimpse from their bedrooms should be allowed to burn for long-term strategic purposes. Nor have denizens of the so-called “wildland-urban interface” been receptive to the idea that controlled burns, set and supervised by government employees, are necessary to thin out cluttered woodlands. In fact, when the Forest Service attempted to burn off some high-risk brush near Prescott, Ariz., a few years ago, angry locals threatened to kill anyone involved in the operation.”

(5)  A look at some of the peer-reviewed literature about fires

Red emphasis added.

(a)  Always start with the IPCC:  from Working Group 1 report of AR5, section 6.8.1. This does not support claims of increased fires today, or that we will see large increases in the near future.

“Models predict spatially variable responses in fire activity, including strong increases and decreases, due to regional variations in the climate–fire relationship, and anthropogenic interference. Wetter conditions can reduce fire activity, but increased biomass availability can increase fire emissions. Using a land surface model and future climate projections from two GCMs, Kloster et al. (2012) projected fire carbon emissions in 2075–2099 that exceed present-day emissions by 17 to 62% depending on scenario. Future fire activity will also depend on anthropogenic factors especially related to land use change.”

(b)  “Using Fire Return Interval Departure (FRID) Analysis to Map Spatial and Temporal Changes in Fire Frequency on National Forest Lands in California” by Hugh D. Safford and Kip M. Van de Water, US Forest Service research paper, January 2014. A detailed look at the fire history of Northern and Southern California.

(c) Examining Historical and Current Mixed-Severity Fire Regimes in Ponderosa Pine and Mixed-Conifer Forests of Western North America” by Dennis C. Odion et al. at PLoS ONE, 14 February 2014 — Abstract.

“There is widespread concern that fire exclusion has led to an unprecedented threat of uncharacteristically severe fires in ponderosa pine (Pinus ponderosa Dougl. ex. Laws) and mixed-conifer forests of western North America. These extensive montane forests are considered to be adapted to a low/moderate-severity fire regime that maintained stands of relatively old trees.

“However, there is increasing recognition from landscape-scale assessments that, prior to any significant effects of fire exclusion, fires and forest structure were more variable in these forests. Biota in these forests are also dependent on the resources made available by higher-severity fire. A better understanding of historical fire regimes in the ponderosa pine and mixed-conifer forests of western North America is therefore needed to define reference conditions and help maintain characteristic ecological diversity of these systems.

“We compiled landscape-scale evidence of historical fire severity patterns in the ponderosa pine and mixed-conifer forests from published literature sources and stand ages available from the Forest Inventory and Analysis program in the USA. The consensus from this evidence is that the traditional reference conditions of low-severity fire regimes are inaccurate for most forests of western North America. Instead, most forests appear to have been characterized by mixed-severity fire that included ecologically significant amounts of weather-driven, high-severity fire.

“Diverse forests in different stages of succession, with a high proportion in relatively young stages, occurred prior to fire exclusion. Over the past century, successional diversity created by fire decreased. Our findings suggest that ecological management goals that incorporate successional diversity created by fire may support characteristic biodiversity, whereas current attempts to “restore” forests to open, low-severity fire conditions may not align with historical reference conditions in most ponderosa pine and mixed-conifer forests of western North America.”

(d)  Looking at current fires and future fires: “Extreme Fire Season in California: A Glimpse Into the Future?” by Jin-Ho Yoon et al. in Bulletin of the American Meteorological Society, December 2015 — Conclusion:

“Our result, based on the CESM1 outputs, indicates that man-made global warming is likely one of the causes that will exacerbate the areal extent and frequency of extreme fire risk, though the influence of internal climate variability on the 2014 and the future fire season is difficult to ascertain.”

(e)  “Impact of anthropogenic climate change on wildfire across western US forests” by John T. Abatzogloua and A. Park Williams in PNAS, 18 October 2016.

“Increased forest fire activity across the western United States in recent decades has contributed to widespread forest mortality, carbon emissions, periods of degraded air quality, and substantial fire suppression expenditures.

“Although numerous factors aided the recent rise in fire activity, observed warming and drying have significantly increased fire-season fuel aridity, fostering a more favorable fire environment across forested systems. We demonstrate that human-caused climate change caused over half of the documented increases in fuel aridity since the 1970s and doubled the cumulative forest fire area since 1984. This analysis suggests that anthropogenic climate change will continue to chronically enhance the potential for western US forest fire activity while fuels are not limiting.”

Although this is an outlier in the literature, it is endlessly cited. This study ignores the effect of “suppression and wildland fire use policies, ignitions, land cover (e.g., exurban development), and vegetation changes”, although they “have likely added to the area burned across the western US forests.”

(f)  “Human-started wildfires expand the fire niche across the United States” by Jennifer K. Balcha et al. in PNAS, 14 March 2017.  See an interview with the lead author in “Who is starting all those wildfires? We are” by Warren Cornwall in Science, 12 September 2017. Abstract.

“The economic and ecological costs of wildfire in the United States have risen substantially in recent decades. Although climate change has likely enabled a portion of the increase in wildfire activity, the direct role of people in increasing wildfire activity has been largely overlooked. We evaluate over 1.5 million government records of wildfires that had to be extinguished or managed by state or federal agencies from 1992 to 2012, and examined geographic and seasonal extents of human-ignited wildfires relative to lightning-ignited wildfires.

“Humans have vastly expanded the spatial and seasonal “fire niche” in the coterminous United States, accounting for 84% of all wildfires and 44% of total area burned. During the 21-y time period, the human-caused fire season was three times longer than the lightning-caused fire season and added an average of 40,000 wildfires per year across the United States. Human-started wildfires disproportionally occurred where fuel moisture was higher than lightning-started fires, thereby helping expand the geographic and seasonal niche of wildfire. Human-started wildfires were dominant (>80% of ignitions) in over 5.1 million km2 , the vast majority of the United States, whereas lightning-started fires were dominant in only 0.7 million km2 , primarily in sparsely populated areas of the mountainous western United States.

Ignitions caused by human activities are a substantial driver of overall fire risk to ecosystems and economies. Actions to raise awareness and increase management in regions prone to human-started wildfires should be a focus of United States policy to reduce fire risk and associated hazards.”

(6) For more research about North American wildfires

See this slideshow by Scott St. George, Associate Professor of Geography at the University of Minnesota (University page, his website).

(7)  For More Information

If you liked this post, like us on Facebook and follow us on Twitter. For more information see posts about the keys to understanding climate change, about droughts, and especially these…

  1. Key facts about the drought that’s reshaping California.
  2. The Texas drought ends; climate alarmists wrong again!
  3. Are 30 thousand species going extinct every year?
  4. Lessons learned from the end of California’s “permanent drought”.
  5. What you need to know about hurricanes and their trends.
  6. Good news about CO2 emissions. Progress to a better world.
  7. A story showing why America’s forests are burning.

New books about these massive wildfires.

Megafire: The Race to Extinguish a Deadly Epidemic of Flame by Michael Kodas.

Firestorm: How Wildfire Will Shape Our Future by Edward Struzik.

Megafire: The Race to Extinguish a Deadly Epidemic of Flame
Available at Amazon.
Firestorm: How Wildfire Will Shape Our Future
Available at Amazon.


8 thoughts on “Is climate change the culprit causing California’s wildfires?”

  1. The Man Who Laughs

    Thank you in particular for the graph of burned forest in the US. Hard data is becoming like panning for gold in these times. You have to sift through a lot of mud.

    1. Larry Kummer, Editor

      The Man,

      I know what you mean, but would express it differently. The media, including the news media, flood us with carefully selected data that supports the approved narrative. In this case, there are countless graphs of US acreage burned since ~1990. Some back to 1980. But not long-term graphs or graphs of areas outside the US (those ruin the narrative, so are doubleplusungood).

  2. Australia is another area regularly plagued by fires, often with disastrous results. One of the earliest records is in Captain James Cook’s journals where he described the eastern coastline covered in a pall of smoke. Most Australian fires are attributed to lightning strikes, but humans are known to start them. Geoffrey Blainey, sometime Professor of Australian History at the University of Melbourne said at an after dinner address, more years ago than I wish to remember, the Aborigines were known to have fire and to start fires, for hunting purposes. But, he said, they were never known to put them out. He even speculated about the possibility that such practises might have caused the extinction of the giant marsupials.

    Our closest experience while living in Australia was a fire in December 1972 which came within 100m of our home. Curiously, for an Australian fire, there was little wind that day. As Californians know, eucaplypts cause very hot crown fires and the depletion of oxygen causes air to rush in to replace it, generating strong winds. 80 properties were destroyed in our immediate vicinity that day with several hundred being the toll in the wider area. Fortunately no one was killed. I used to ride a blue-painted motor bike in those days and I was stopped by a traffic patrol the next morning, riding into Melbourne. The reason? Aerial spotters (fixed wing) had observed someone on a blue motor bike riding away from several hotspots over the course of the afternoon and early evening. It took a couple of years to find and prosecute the perpetrator.

    Over the last 40 years there have been more devastating fires in South Eastern Australia causing property loss and deaths. Ecological management, forced by green policies seem to have created the conditions for the devastation caused by these fires, the greatest attribution being lack of management of forest litter.

    That fires have been part of the Australian scene for eons is indicated by nature. Several species of Australian trees require the heat of a forest fire to crack open the seed cases so that the seeds can germinate. I assume that the carbon rich ash left by the fire assists in the germination.

    1. Larry Kummer, Editor


      Thank you for the report on wildfires from Down Under. That reminds me of half-remembered readings from college (long ago) about Native America’s use of fire that created much of the North America’s Great Plains.

      It is easy to forget the powerful transformative effect of people even without metal tools other than iron from meteors (i.e., before the first industrial age).

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