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California’s wildfire smoke and climate change: 4 things to know

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California wildfires every year emit as much carbon as almost 2 million cars, posing a threat to efforts to battle climate change.

Wildfires and climate change are locked in a vicious circle: Fires worsen climate change, and climate change worsens fires.

Scientists, including those at the World Resources Institute , have been increasingly sounding the alarm about this feedback loop, warning that fires don’t burn in isolation — they produce greenhouse gases that, in turn, create warmer and drier conditions that ignite more frequent and intense fires. 

Last week, wildfire smoke prompted another round of unhealthy air quality in California. Fires in Oregon and Northern California sent smoke into Sacramento and the San Francisco Bay Area. And it’s a global nightmare: This summer, world temperatures hit an all-time high , the worst U.S. wildfire in more than a century devastated Maui, a deadly fire in Greece was declared Europe’s largest ever, and swaths of the Midwest and Northeast have been blanketed by smoke from Canada’s forest fires. 

As California’s most intense wildfire months approach, the volume of greenhouse gases they emit is expected to grow.

A bill by Assemblymember Bill Essayli , a Republican from Riverside, introduced this year would have required the state to count wildfire emissions in its efforts to reduce statewide greenhouse gases. But the bill didn’t get far: It was defeated in committee.

Here are answers to some of the key questions raised by the symbiotic relationship between wildfires and climate change:

What’s happening to carbon emissions as wildfires worsen? 

Scientists around the world are trying to quantify just how much wildfires contribute to climate change.

Last year, California wildfires sent an estimated 9 million metric tons of carbon dioxide into the atmosphere, according to California Air Resources Board estimates . That’s equivalent to the emissions of about 1.9 million cars in a year.

In 2020, California’s wildfires were its second-largest source of greenhouse gases, after transportation, according to a study published last year . The researchers from UCLA and the University of Chicago concluded that the 2020 wildfires increased overall emissions by about 30%.

When forests burn, carbon dioxide and other greenhouse gases are released into the air. It’s considered part of a natural cycle, with plants absorbing and then releasing the chemicals into the air over time. But experts say the increasing frequency of fires might be throwing this cycle out of balance .

Emissions this year from Canada’s forests have shattered records, according to the European Union’s Copernicus Atmosphere Monitoring Service. Last year, carbon dioxide from boreal forests — the world’s northernmost forests, which span vast swaths of Canada and Alaska — hit a record high, UC Irvine researchers reported in the journal Science .

 “Where does that carbon go? It goes up into the atmosphere, it circles all around the globe, it’s affecting all of us.” Char Miller, Pomona College

Fires in these northern latitudes are of deep concern to researchers, as those forests historically were too cold to experience significant burns. They are incredibly dense, and emit methane from the permafrost that lies beneath them.

“These are forests that haven’t burned, not just in decades but probably centuries,” said Char Miller, an environmental professor at Pomona College in Claremont. “Where does that carbon go? It goes up into the atmosphere, it circles all around the globe, it’s affecting all of us. It’s both symbolic and I think really significant. The coldest part of the planet is also exploding in fire.”

In addition, wildfires emit methane, which is a much more potent greenhouse gas than carbon dioxide, according to a study published earlier this summer .

Will wildfire smoke derail the state’s climate goals?

Researchers are increasingly calling attention to how forest fires might be eroding the state’s climate goals , with UCLA scientists describing the state’s efforts as “up in smoke.”

Michael Jerrett, a professor at the UCLA Fielding School of Public Health, said nearly two decades worth of emission reductions from power plants were threatened by the 2020 fires, which included some of California’s largest and most destructive fires .

“Essentially, the positive impact of all that hard work over almost two decades is at risk of being swept aside by the smoke produced in a single year of record-breaking wildfires,” Jerrett said in a statement.

Some experts say carbon emissions from wildfires are not much of a concern — that the carbon captured by trees, brush and grasses already existed in the atmosphere so its release during fires is part of a natural cycle. As a result, they say, those emissions shouldn’t be considered net contributors to climate change.

“These are distractions from the real issue which is that we need to generate a lot more renewable energy to displace our use of fossil fuels,” Anthony Wexler, director of the Air Quality Research Center at UC Davis, wrote to CalMatters in an email.

On the other hand, some experts say carbon is carbon — and that it all contributes to climate change. Jerrett and the other authors of the UCLA report said wildfire emissions should be a bigger part of California’s climate policy.

For its part, the California Air Resources Board estimates emissions from wildfires, but it doesn’t count them against greenhouse gas targets for 2030. The targets are based only on gases produced by industries, energy, transportation and other human sources . 

Last year, Gov. Gavin Newsom signed into law a requirement that the state achieve net-zero emissions as quickly as possible, no later than 2045. That mandate means the state will have to ultimately consider the roles of natural and working lands, said David Clegern, an air board spokesman. However, some wildfires are “part of the natural cycle and should not count against targets,” Clegern wrote in an email.

Clegern said “it’s difficult to know” how much carbon from wildfires “might reduce the effectiveness of the state’s climate programs.”

“That’s because to a certain extent wildfire smoke is part of a natural carbon cycle…We cannot yet draw a bright line to accurately measure that impact,” he said.

Instead, he said scaling back fossil fuels has to be California’s priority. 

“California is working on reducing wildfire in an all-hands-on-deck manner, but we won’t really fix the problem until we quit pumping more fossil fuel emissions into the atmosphere,” Clegern said.

How does the state plan to deal with carbon from fires? 

State officials say restoring the health of forests and taking steps to make sure they are more resilient to fires will result in fewer wildfires and fewer climate-changing emissions. 

Air board models project that natural and working lands — forests, rangelands, urban green spaces, wetlands and farms — will be a net source of emissions through 2045, while at the same time these lands will experience a decrease in the trees, shrubbery, soil and other natural features that naturally sequester carbon.

That’s why the proper management of these undeveloped lands will be important in the coming two decades. More than half of California’s forestland is managed by the federal government, and the Newsom administration announced in 2021 that it was working with the Biden administration to better manage forests and build fire resilience.

“These lands can be part of the climate solution, but we need to increase our efforts to reduce their emissions and improve their ability to store carbon into the future,” Clegern said. 

Burning forests might be complicating the state’s climate goals in other ways, too. California’s carbon offset market has been threatened by out-of-state wildfires, the online publication Grist reported, because the state awards credits to companies that maintain forests elsewhere to store carbon.

What about the impact on smog and soot?

Wildfire smoke is toxic, containing substances such as carbon monoxide and benzene, a carcinogen. Smoke’s tiny particles of soot are considered its most hazardous ingredient, since they can enter airways, lodge in lungs and trigger asthma or heart attacks. Local air quality districts regularly send out warnings in California when wildfires spread smoke, sometimes hundreds of miles from the fires.

Smoke may be negating some of California’s hard-fought clean-air gains . A report last year by the Energy Policy Institute of Chicago found that some California counties were more polluted than they were in 1970. In 2020, more than half of California counties experienced their worst air pollution since 1998, according to the report.

California’s air quality agencies do not have to consider wildfire smoke when they outline plans to attain health standards for air pollutants, such as fine particles and ozone. That’s because fires are considered “exceptional events” under the federal Clean Air Act.

“Even though the frequency of wildfires is increasing, we have no reason to believe that (U.S.) EPA will change how wildfire emissions are treated under the exceptional events process,” Clegern said.

Meanwhile, concern about the impact of smoke on communities is growing. Nitrogen oxides, which form smog, appear to be increasing in rural areas — largely due to wildfires, according to a recent UC Davis study .

“If you go to these remote forests — which are predominantly in the north and the Sierras in the south — what you find is that there’s this large increase,” said study co-author Ian Faloona , a UC Davis bio-micro-meteorologist.

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Implications of the California Wildfires for Health, Communities, and Preparedness: Proceedings of a Workshop (2020)

Chapter: 1 introduction and overview, 1 introduction and overview.

California and other wildfire-prone western states have experienced a substantial increase in the number and intensity of wildfires in recent years. Eight of the 10 largest wildfires in California have occurred since 2000. In November 2018 the Camp Fire in northern California killed at least 85 people and destroyed more than 18,000 structures, becoming California’s deadliest and most destructive wildfire on record (see Figure 1-1 ). Wildlands and climate experts expect these trends to continue and quite likely to worsen in coming years.

Wildfires and other disasters can be particularly devastating for vulnerable communities ( Fothergill et al., 1999 ). Members of these communities tend to experience worse health outcomes from disasters, have fewer resources for responding and rebuilding, and receive less assistance from state, local, and federal agencies. Because burning wood releases particulate matter and other toxicants, the health effects of wildfires extend well beyond burns. In addition, deposition of toxicants in soil and water can result in chronic as well as acute exposures. Vulnerable communities tend to have fewer resources with which to prepare for and respond to environmental disasters such as a wildfire. Even relatively small expenses, such as tree trimming, brush removal, or other fire prevention services, may be beyond the financial means of community members.

On June 4–5, 2019, four different entities within the National Academies of Sciences, Engineering, and Medicine—the Forum on Medical and Public Health Preparedness for Disasters and Emergencies; the Roundtable on Population Health Improvement; the Roundtable on the Promotion of Health Equity; and the Roundtable on Environmental Health

Services, Research, and Medicine—held a workshop titled Implications of the California Wildfires for Health, Communities, and Preparedness at the Betty Irene Moore School of Nursing at the University of California (UC), Davis. The Statement of Task can be found in Appendix A . For reference, see Figure 1-2 for a map of California counties and major cities. As Kenneth Kizer, distinguished professor in the UC Davis School of Medicine and the Betty Irene Moore School of Nursing and chair of the planning committee for the workshop, said in his welcoming remarks, a major challenge facing the planning committee was the amount of material that could be presented at the workshop. 1 “One of the underlying premises of this workshop is that the nature of the wildfires that we have seen in the last few years is the ‘new normal,’ both in the frequency and number

___________________

1 The planning committee for the workshop was Kenneth Kizer ( Chair ), Julie Baldwin, Michelle Bell, Wayne Cascio, David Eisenman, Richard Jackson, Wayne Jonas, Suzet McKinney, and Winston Wong. Support for the workshop came from The California Endowment, the California Wellness Foundation, the Gordon and Betty Moore Foundation, the National Institute of Environmental Health Sciences, the U.S. Environmental Protection Agency, and the sponsors of the National Academies’ roundtables and forums.

of different locations and in the intensity of fires, and that what we have seen is going to be repeated in the future,” said Kizer, who worked as a firefighter during college. Many communities and populations are at risk and want to know what they can do to prevent and prepare for wildfires, “because what we have seen in the past few years is going to be what we see going forward.”

Wildfires are creating a new model of a public health crisis, added David Lubarsky, vice chancellor of human health sciences at UC Davis and chief executive officer of UC Davis Health. Wildfires are intensive and unplanned long-term events that pose complex and wide-ranging problems. Population growth, climate change, weather extremes, intermittent droughts, record rains, and other factors are interacting in ways that are difficult to dissect, understand, and ameliorate. Earthquakes, mudslides, urban unrest, and other issues are usually here and then gone, said Lubarsky. In contrast, large wildfires can go on for long periods of time and have wide-ranging and long-lasting impacts across large areas.

The issues posed by wildfires have caught the attention of academic health systems around the nation, Lubarsky noted. For example, he had recently written an editorial about air quality in Sacramento following the Camp Fire, which for 5 days was the worst in the world. “I was shocked, because I have been to Shanghai and Beijing on bad days,” he said. “This beat all of them.”

Figuring out how to help people in an acute time frame and then helping to deal with the social devastation, health care interruptions, and health care impacts over the long term are both challenges, Lubarsky said. For example, UC Davis had recently partnered with a hospital in Chico to open a chemotherapy infusion center to give people easier access to chemotherapy following the damage done by the Camp Fire to the Adventist Feather River Hospital in Paradise. “That is one of those things you do not think about. What do you do with people who have chronic illnesses who are dependent on the services that were previously provided in a scarred area?”

Both Lubarsky and Deborah Ward, Dignity Health Dean’s Chair for Nursing Leadership and clinical professor at the Betty Irene Moore School of Medicine, who also spoke during the opening session, observed that UC Davis was a leader in the response to the Camp Fire. Students at the School of Nursing and elsewhere immediately stepped up to respond to the unfolding disaster occurring in and around Paradise, Ward said. They collected and delivered goods and supplies and worked at shelter clinics, in part to care for frail, elderly evacuees. They spent countless hours providing urgently needed care to victims of the fire. They encountered amazing and disturbing episodes, according to Ward. “One of our nursing students, Brandon, suddenly found himself caring for people whose feet were burned as they had raced from their homes trying to escape the fire.” As one nursing student observed to Ward, “This is a good reminder of why we want to be health care providers. This is about serving our community and meeting its needs.”

Lubarsky pointed out that UC Davis researchers have been investigating the impact of environmental toxins on populations, including the effects of wildfire smoke. “Figuring out how we are going to actually make a dif-

ference in the trajectory of the people and our environment that has been impacted by the fires is incredibly important for northern California,” he said.

A highlight of the workshop was the public debut of a documentary titled Waking Up to Wildfires produced by the UC Davis Environmental Health Sciences Center and funded by the National Institute of Environmental Health Sciences. 2

ORGANIZATION OF THE WORKSHOP

This summary of the workshop largely parallels the workshop agenda (see Appendix B ). Chapter 2 provides an overview of wildfires in California and also looks at a particular wildfire in southwestern Colorado. Climate change is contributing to an intensification of wildfires in the western United States, these speakers said, which is requiring a greater breadth and depth of potential responses. Considerations of health equity are a critical aspect of these responses and can help all communities and populations become more resilient to future wildfires.

Chapter 3 discusses the populations impacted by wildfires, especially the vulnerable populations and communities that experience disproportionate impacts from natural disasters. As speakers in this panel pointed out, these communities also have experiences and traditional knowledge that can reduce not only their own vulnerability but that of other groups.

Chapter 4 examines the wide-ranging health effects of wildfires, including effects on the respiratory system, cardiovascular system, and immune system. Some of these effects are acute and others chronic, pointing to the need to begin research quickly after a wildfire event. Doing such research requires good measures of both exposures and health effects, and each measure has its own challenges. New technologies could help in both areas.

Chapter 5 looks at the recovery process, reversing the usual order of discussing preparedness first, response second, and recovery third. Coordination at all levels of government and among sectors is a theme of long-term recovery processes, given that much of the burden for recovery typically falls on states and local communities. In addition, communities have distinct resources, such as nearby academic institutions, that can help them recover from wildfires in ways that are particularly suited to local situations.

Chapter 6 considers how to enhance operational response to wildfires. The responses to wildfires can be wide ranging and involve a variety of public- and private-sector institutions. Leveraging the expertise of these

2 The trailer for the film, which features several people who spoke at the workshop, is available at https://www.youtube.com/watch?v=v24296K-qVE (accessed November 25, 2019).

organizations and coordinating activities can increase the effectiveness of responses and reduce both the physical and the mental health effects of wildfires.

Chapter 7 turns to the potential for mitigation and preparedness. These activities are also wide ranging and have long time frames and extensive planning requirements. Yet, they shape the response and recovery actions that take place on short- and medium-term time frames. The zoning, design, construction, and maintenance of structures, for instance, can have a critical influence on what happens during and after a wildfire.

Chapter 8 , the final chapter, closes the proceedings with the reflections of panel moderators and members of the roundtables and forum that organized the workshop on the themes that emerged and their implications for the future.

California and other wildfire-prone western states have experienced a substantial increase in the number and intensity of wildfires in recent years. Wildlands and climate experts expect these trends to continue and quite likely to worsen in coming years. Wildfires and other disasters can be particularly devastating for vulnerable communities. Members of these communities tend to experience worse health outcomes from disasters, have fewer resources for responding and rebuilding, and receive less assistance from state, local, and federal agencies. Because burning wood releases particulate matter and other toxicants, the health effects of wildfires extend well beyond burns. In addition, deposition of toxicants in soil and water can result in chronic as well as acute exposures.

On June 4-5, 2019, four different entities within the National Academies of Sciences, Engineering, and Medicine held a workshop titled Implications of the California Wildfires for Health, Communities, and Preparedness at the Betty Irene Moore School of Nursing at the University of California, Davis. The workshop explored the population health, environmental health, emergency preparedness, and health equity consequences of increasingly strong and numerous wildfires, particularly in California. This publication is a summary of the presentations and discussion of the workshop.

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• Original research
• Open access
• Published: 25 August 2021

Large California wildfires: 2020 fires in historical context

• Jon E. Keeley   ORCID: orcid.org/0000-0002-4564-6521 1 , 2 &
• Alexandra D. Syphard 3  

Fire Ecology volume  17 , Article number:  22 ( 2021 ) Cite this article

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California in the year 2020 experienced a record breaking number of large fires. Here, we place this and other recent years in a historical context by examining records of large fire events in the state back to 1860. Since drought is commonly associated with large fire events, we investigated the relationship of large fire events to droughts over this 160 years period.

This study shows that extreme fire events such as seen in 2020 are not unknown historically, and what stands out as distinctly new is the increased number of large fires (defined here as > 10,000 ha) in the last couple years, most prominently in 2020. Nevertheless, there have been other periods with even greater numbers of large fires, e.g., 1929 had the second greatest number of large fires. In fact, the 1920’s decade stands out as one with many large fires.

Conclusions

In the last decade, there have been several years with exceptionally large fires. Earlier records show fires of similar size in the nineteenth and early twentieth century. Lengthy droughts, as measured by the Palmer Drought Severity Index (PDSI), were associated with the peaks in large fires in both the 1920s and the early twenty-first century.

Antecedentes

En el año 2020, California experimentó un récord al quebrar el número de grandes incendios. Aquí situamos a éste y otros años en un contexto histórico mediante el examen de registros de incendios en el estado desde 1860. Dado que la sequía es frecuentemente asociada a grandes eventos de incendios, investigamos la relación entre grandes incendios y sequías en este período de 160 años.

Este estudio mostró que eventos extremos como el visto en 2020 no son históricamente desconocidos, y lo que se muestra como distintivamente nuevo es el incremento en el número de grandes incendios (definidos aquí como > 10.000 ha) en el último par de años, y más prominentemente en 2020. Sin embargo, ha habido otros períodos con aún mayores números de incendios (i.e. en 1929 hubo mayor número de incendios que en cualquier otro año del registro). De hecho, la década de 1920, fue una de las que presentó mayor número de grandes incendios.

Conclusiones

En la última década ha habido muchos años con incendios excepcionalmente grandes. Antiguos registros muestran incendios de tamaño similar tanto en el siglo 19 como en el siglo 20. Sequías prolongadas, medidas mediante el Índice de Sequías Severas de Palmer (PDSI), fueron asociadas con los picos de grandes incendios tanto en el siglo 20 como en el 21.

Introduction

The western US has a long history of large wildfires, and there is evidence that these were not uncommon on pre-EuroAmerican landscapes (Keane et al. 2008 ; Baker 2014 ; Lombardo et al. 2009 ). One of the biggest historical events was the 1910 “Big Blowup,” which reached epic proportions and was an important impetus for fire suppression policy (Diaz and Swetnam 2013 ). California in particular has had a history of massive wildfires such as the 100,000 ha 1889 Santiago Canyon Fire in Orange County or the similarly large 1932 Matilija Fire or 1970 Laguna Fire (Keeley and Zedler 2009 ).

While large fires are known in the historical record, in the first few decades of the twenty-first century, the pace of these events has greatly accelerated (Keeley and Syphard 2019 ). In the last decade, the state has experienced a substantial number of fires ranging from 10,000 ha to more than 100,000 ha, and these have caused massive losses of lives and property. The largest fires on record were recorded in 2018 and then were replaced with even larger fires in 2020, although some of these were the result of multiple fires that coalesced into fire complexes of massive size.

Causes for these fires are multiple, but climate change has been implicated as a critical factor (Williams et al. 2019 ; Abatzoglou et al. 2019 ). Historically, drought has often been invoked as a driver of large fires (Keeley and Zedler 2009 ; Diaz and Swetnam 2013 ), and California has experienced an unprecedented drought in the last decade (Robeson 2015 ). However, factors such as management impacts on forest structure and fuel accumulation, made worse by the recent drought, are critically important in some ecosystems (Stephens et al. 2018 ).

To put these recent fires in a historical context, we have investigated the history of large wildfires in California. “Large” fires is an arbitrary designation, e.g., Nagy et al. ( 2018 ) considered it to be 1000 ha or more. Our focus, however, is on those fires that made 2020 particularly noteworthy; so we define large fires as those in the top 1–2% of all fires, which is approximated by fires > 10,000 ha. In addition, we have examined the relationship of large fires to drought.

The database of fires > 10,000 ha was assembled from diverse sources. From 1950 to the present, the State of California Fire and Resource Assessment Program (FRAP) fire history database was relatively complete, but less so prior to 1950 (Syphard and Keeley 2016 ; Miller et al. 2021 ). In California, US Forest Service (USFS) annual reports provide statistics on fires by ignition source and area burned back to 1910 and Cal Fire back to 1919 (Keeley and Syphard 2017 ), and although these reports focused on annual summaries, they often provided descriptions of very large fires. A rich but under-utilized historical record for early years was the exhaustive compilation of fires in a diversity of documents from 1848 to 1937, assembled by a USFS project and brought to our attention by Cermak’s ( 2005 ) USFS report on Region 5 fire history. This source presents all documents (including agency reports and newspaper reports on fire, vegetation, timber harvesting and Native Americans) for all counties in the state and comprises 69 bound volumes (USDA Forest Service 1939-1941 ). We utilized these documents where they presented data on fire size, either an estimate of acres burned or dimensions of the burned area. We did not include fire reports that lacked a clear indication of area burned; e.g., the 1848 fire described in the region of Eldorado County referred to an immense plain on fire and all the hills blackened for an extensive distance (USDA Forest Service 1939-1941 ), but lacked more precise measures.

Other sources included the following: Barrett ( 1935 ), based on USFS records and personal experiences as well as “early-day diaries, historical works, magazines and newspapers.” Greenlee and Moldenke ( 1982 ) included fire records from state and federal agencies as well as library and museum archives. Morford ( 1984 ) was based on unpublished USFS records accumulated during the author’s 41 years in that agency. Keeley and Zedler ( 2009 ) was based on records retrieved from the California State Archives and State Library. Cal Fire ( 2020 ) data, not part of the FRAP database, included agency records of individual fire reports (not available to the public but searchable by the State Fire Marshall Kate Dobrinsky). In a few cases, the same fire was reported by more than one source, sometimes with different sizes; when this occurred after 1950, we used the FRAP data and before that either Cermak ( 2005 ) or Barrett ( 1935 ) over other sources.

Reliability of these data sources is an important question to address. Stephens ( 2005 ) contended that USFS data before 1940 were unreliable, an assertion based on Mitchell ( 1947 ); but Mitchell ( 1947 ) provided no evidence that early data were inaccurate, only that many states lacked early records. Mitchell ( 1947 ) was considering availability of state and federal data for the entire USA; however, California has far better historical records at both the state and federal archives than much of the USA (Keeley and Syphard 2017 ). USFS records for California were reported annually for all forests beginning in 1910 and for state protected lands by Cal Fire back to 1919. The latter agency had by 1920 several hundred fire wardens strategically placed throughout the state and each warden was held to a strict standard of reporting all fires in their jurisdiction.

Before 1910, data on fires was dependent on unpublished reports available in state and federal archives, observations published in books, data given in newspaper accounts of fire events, and estimates from fire-scar chronology studies. It was suggested by Goforth and Minnich ( 2007 ) that early newspaper reports were exaggerations and represented “yellow journalism,” a pejorative term that connoted unethical journalism. This was based on what they considered sensational headlines, but comparison of nineteenth century with more recent newspaper headlines provides no basis for this conclusion (Keeley and Zedler 2009 ). As a journalist colleague suggested, “a century-old newspaper story is not a precise source …[but] is the first draft of history and a valuable source of first person account from long past events.” Such information qualifies as scientific evidence, which is defined as evidence that serves to either support or counter a scientific theory or hypothesis, is empirical, and interpretable in accordance with scientific method. The data we present falls within these bounds and that includes newspaper reports as we used data on fire size in terms of acres or dimensions of burned landscape reported. Recently Howard et al. ( 2021 ) demonstrated that fire-scar records match newspaper accounts in the eastern US. To address the issue of how close newspaper accounts used in this study come to accurately depicting fire size, we have compared fires reported in published sources with newspapers where available. We of course appreciate that early accounts lacked the precise technology available today for outlining fire perimeters; however, this lack of precision does not necessarily translate into less accurate accounts and applies to both newspapers as well as state and federal agencies.

Data were presented for the state and by NOAA divisions North Coast (1), North Interior (2), Central Coast (4), Sierra Nevada (5), and South Coast (6). These are the five most fire-prone divisions of NOAA’s National Climatic Data Center categories, defined as climatically homogenous areas (Guttman and Quayle 1996 ). There of course are other systems that may be useful for comparisons, dependent on the need. For example, the Bailey Ecoregions (Bailey 1980 ), which separates regions by vegetation type, might be thought preferable, but, for our purposes, there is no necessary advantage as large fires usually burn across a mosaic of different vegetation types. A system that might provide a better presentation would be the recently described Fire Regime Ecoregions (Syphard and Keeley 2020 ). However, despite limitations to the NOAA divisions (e.g., Vose et al. 2014 ), it is preferable due to the availability of historical annual data on the Palmer Drought Severity index calculated by NOAA divisions.

Palmer Drought Severity Index (PDSI) was recorded for each year from two sources. From 1895 to 2020, PDSI was the annual mean from NOAA ( 2020a ), and for years prior to 1895, summer PDSI was reconstructed from tree-ring studies (Cook et al. 1999 ). Statistical analysis and graphical presentation were conducted with Systat software (ver. 13.0, Systat Software, Inc., San Jose, CA, http://www.systat.com/ ).

Since some of the fires came from data reported in newspapers, not a typical scientific data base, we did an initial investigation comparing FRAP reported fire size with size reported in newspaper reports. This was not an exhaustive study since FRAP data before 1950 presents relatively few fires by date or fire name making it difficult to match up fires with newspaper reports; however, we found half a dozen potential comparisons (Table 1 ). As to be expected these different reports are not identical in fire size, however, they were quite similar; sometimes, newspapers over reported area burn but other times under reported, although most importantly, they were of similar magnitude as those in the FRAP database. Data sources varied over time (Table 2 ); from 1950 to the present, large fires were all recorded in the FRAP database. Prior to that year, sources were mostly from USFS ( 1939-1941 ).

Fire size of all fires over 10,000 ha during the last 160 years are shown in Fig. 1 a. Exceptionally large fires followed a bimodal pattern with peaks in the nineteenth century and again in the twenty-first century, separated by a low point in the 1950s. From 1860 to 1950, there was a significant decrease in large fire size followed by a significant increase in the second half of the record. Although the trends were highly significant, the great year to year variation in size of large fires, gave low r 2 values, indicating limited ability to predict fire size for any given year.

a Fire size for large fires from 1860 to 2020. b Frequency of large fires over this same time period

To illustrate the temporal distribution of record-breaking fires, we picked the top 3% ( n = 12) of all fires based on size, and these are shown in (Table 3 ). Not surprisingly, 5 occurred in the year 2020; however, four occurred in the nineteenth century.

The data presented in this paper greatly expands our understanding of the history of large fires in California. To date, our dependence has been on the FRAP database and they clearly acknowledge their records are for fires from 1950 to the present, and this is borne out by our analysis (Table 2 ), but the records presented here extend the fire history back nearly a century. Over the period from 1860 to the present, yearly frequency of fires over 10,000 ha exhibited several prominent peaks (Fig. 1 b). A few peak years occurred in the 1920s, with one of the highest frequencies recorded throughout the entire 160 year record in 1929. There were also peaks in 2007 and 2008 and again in 2018 and 2020.

Through time, the distribution of fire size varied between NOAA divisions (Fig. 2 ). The North Interior (2), Sierra Nevada (5), and South Coast (6) divisions all exhibited a significant decline in fire size from the nineteenth century till 1950. Although all the regions exhibited the largest fires in the last decade, only in the Central Coast (4) was this significant for the years 1950–2020.

Large fires within NOAA Divisions. Statistics are presented for significant trends

Frequency of fires over 10,000 ha are presented by decade for each of the five divisions (Fig. 3 ). Consistent with the statewide pattern (Fig. 1 b), all showed a spike in number of large fires in the 1920s and again after 2000. The 1920s peak was particularly prominent in the Sierra Nevada (5) and South Coast. Also, for the Central Coast and Central Sierra Nevada regions, the number of fires in the 1920s was higher than that for recent years. For the years 1860 to 1949 and for the years 1950 to 2020 separately, there was no significant change in frequency over time.

Decadal frequency of large fires within NOAA Divisions. Note the decade 2020 is represented by a single year.

One aspect of climate over the entire period is captured by the PDSI, a drought index that includes patterns of both precipitation and temperature. There have been several periods of drought over the past 160 years, the most severe being in the decades 1920-1930 and 1990-2020 (Fig. 4 a). These periods also correlate with periods of large amounts of area burned by large fires (Fig. 4 b). Bivariate regression analysis showed that over the period from 1860 to 2020, there was a significant relationship between PDSI and area burned (adj r 2 = 0.429, P = 0.003).

a PDSI for the decades from 1860 to 2020. b Area burned by fires > 10,000 ha for the decades from 1860 to 2020. Note the decade 2020 is represented by a single year

Clearly, 2020 was a phenomenal fire year in California for record breaking large fires. However, this study shows that such extreme fire events are not unknown historically, and what stands out as distinctly new is the increased number of large fires (defined here as > 10,000 ha) in the last couple of years, most prominently in 2020. Given that historically we have seen years with even greater number of large fire events, e.g., 1929, a comprehensive evaluation of the factors leading up to large fire event years is clearly needed.

The largest fire in recorded history for the state is the 2020 August Complex Fire, which comprised 38 separate fires that were considered a single a massive 418,000 ha fire (Cal Fire 2020 ). Thus, the merging of these multiple fires into a larger event is certainly a factor affecting “fire” size. Indeed, some 2020 fire complexes included multiple fires that never actually merged; for example, the LNU Complex Fire, which ranked within the top 12 fires (Table 3 ), actually comprised several distinctly separate fires that apparently did not merge (San Francisco Chronicle 2020 ).

It has been contended that large fires in the past were often very different in nature from contemporary large fires. For example, many southwestern US mixed conifer forest large fire events in the nineteenth century were low-intensity surface fires, unlike contemporary large fires that are dominated by high-intensity crown fire (Keane et al. 2008 ). This contention, however, varies from descriptions of the top 12 fires recorded here (Table 3 ). For example, when describing the 1889 Plumas fire, newspaper reports state “A large amount of timber and fire wood [were] destroyed.” One report describes the 1891 Eldorado fire as “the most terrible forest fire ever experienced in California…fanned by a strong north wind has swept over almost the entire stretch of country between Georgetown and Salmon Falls…Magnificent forests of a few days ago have been burned over and blackened and lofty pines seared and killed. The scene at night baffles all powers of description, there being a moving mass of fire as far as the eye can reach.” The 1909 Santa Cruz fire was described as “this large conflagration spread… [and] the country is entirely burned over; the entire growth on Loma Prieta Peak and its sides down to Los Gatos Creek is a charred area.”

In general, very few of the large fires reported in (USDA Forest Service 1939-1941 ) were described as low-intensity surface fires. This source described forest fires up and down the state as high intensity conflagrations. For instance, in San Diego County, the 19,000 ha fire of 1870 was described as “the fires which have been raging in the mountains …are wholly unprecedented in extent and …destruction of timber”; in the San Luis Obispo 1869 40,000 ha fire “a great deal of timber and grass has been destroyed”; in Calavaras County in 1889, an 81,000 ha fire was described “A large forest fire has been raging…a large scope of timber country has been laid in waste”; a description of the Tehama 1889 30,000 ha fire was “The forest fire that has raged...was very destructive”, etc. In short, there is little in these records to suggest that nineteenth century large fires were normally less destructive of natural resources than twenty-first century fires. This of course is not meant to negate the commonly accepted paradigm that California forests in the past frequently burned with low-intensity surface fires (Skinner and Chang 1996 ), but that once fires reached epic proportions, and consequently burned through a mosaic of vegetation types, fire behavior appears to have been quite different.

However, one thing that is different between historical large fires and recent ones is that contemporary large fire events are often much more destructive in terms of loss of lives and property. For example, the 2018 Butte County Camp Fire driven by extreme foehn winds killed 85 people and destroyed over 18,000 buildings, however, a similar foehn wind driven fire occurred in Eldorado County in 1891 (Table 3 ), and there were no reports of fatalities and relatively few structures were lost (USFS 1939-1941 ). The difference is due to changes in human demography, e.g., California population throughout the nineteenth century was fewer than 2 million people in contrast to 2020 with a population approaching 40 million. Pressure to find affordable housing has resulted in urban sprawl into watersheds of dangerous fuels (Syphard et al. 2007 , 2019 ). In addition, population growth has played a role in increasing ignitions as most fires that result in human losses are of human origin (Keeley and Syphard 2018 ).

Another factor that is very different in recent decades, when compared to the middle of the century, is the frequency of large fires, with 2007, 2008, 2017, 2018, and 2020 all being peak years for number of large fire events. However, the 1920s were comparable to these recent decades, and in fact, 1929 was a peak year for frequency of large fire events (Fig. 1 b). The1920s decade was also a peak in most regions (Fig. 3 ). Although there was less structure loss in the 1920s, demographic changes could have been involved in terms of frequency of large fires, as the 1920s saw a major influx of people. In this decade, there were increased anthropogenic ignitions driven by greater access to wildlands due to rapid road construction and an order of magnitude increase in car licenses (Keeley and Fotheringham 2001 ).

Climate is widely viewed as a determining factor in fire size, and in particular, drought has been a major driver historically (Little et al. 2016 ; Madadgar et al. 2020 ; Huang et al. 2020 ). One of the important factors behind the 2020 fire events was the anomalously long and intense drought the region experienced beginning in 2012. This drought was experienced across the southern US (Rippey 2015 ) and lasted 3–5 years in California; it was considered to be one of the most severe droughts in California history (Robeson 2015 ; Jacobsen and Pratt 2018 ). The greatest number of recent large fires and size of these fires have been concentrated in the years since this drought (Fig. 4 ). Drought has also been implicated as a factor in other large California fires during the first decade of the twenty-first century (Keeley and Zedler 2009 ) as well as with large fire events in the 1920s, as shown in this study.

While a clear climate signal in terms of drought is a likely driver of big fire events in the state, an emerging issue is the role of anthropogenic climate change (Williams et al. 2019 ). While droughts have historically been a natural occurrence in California’s Mediterranean climate ecosystems, it has been postulated that global warming has made these droughts more severe. Estimates are that the 2012–2014 drought in the Sierra Nevada was perhaps 10–15% more severe due to global warming (Williams et al. 2015 ). This has important implications for the impact of drought on tree and shrub dieback that increases hazardous fuels and contributes to increased fire risk (Stephens et al. 2018 ). However, the relationship between drought and tree dieback in the state is complicated and impacted by competition and other factors (Das et al. 2011 ; Young et al. 2017 ).

The severity of the 2020 fire season in California is not the result of any one factor such as climate change but the result of the “perfect storm” of events. Winter and spring precipitation in the northern part of the state was only about 50% of average, August had a stream of dry lightning storms in northern California that ignited over 5000 fires (Cal Fire 2020 ), there was an intense heat wave in early September that elevated temperatures to record breaking levels (NOAA 2020b ), and forests in the northern half of the state had anomalous fuel loads due to a century of fire suppression and greatly exacerbated by the intense drought of 2012–2015 (Stephens et al. 2018 ).

It is a major challenge to parse out the role of anthropogenic climate change in driving 2020 fires. Certainly, the below normal rainfall year in the north fell within the natural range of variation. The extraordinary lighting storm was perhaps more severe than what is seen in most years, but was not at all unprecedented; e.g., in 2008 northern California experienced a similar event with over 6000 lightning strikes and burning over 400,000 ha from these fires alone, and this is a common phenomenon at a decadal scale, e.g., 1999, 1987, 1977, 1955 (Cal Fire 2008 ). Further contributing to the 2020 fires was the intense heat wave that may be linked to climate change (Gershunov and Guirguis 2012 ; Hully et al. 2020 ). The role of anomalous fuel accumulation due to more than a century of fire suppression and made much worse by 2012–2016 drought was also a major contributor to the size of these fires.

Historically, California fires as big as some of the largest fires in 2020 year have occurred as evident from records beginning in 1860. However, without question, 2020 was an extraordinary year for fires in California. This was driven by a multitude of factors but prominently is the extraordinary droughts the state has experienced in the last couple decades. Peaks in the number of large fires have occurred in the 1920s as well as in the twenty-first century and both occurred in decades with extended droughts.

Availability of data and materials

Data from published sources listed in the “Methods” section.

Abbreviations

California Department of Forestry and Fire Protection

Cal Fire’s Fire and Resource Assessment Program

National Oceanic and Atmospheric Administration

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California Burning: Fire, Drought and Climate Change

Stanford Law School’s Professor Buzz Thompson, one of the country’s leading water law experts, discusses California’s wildfires, drought, water, and climate change  with  Stanford Legal  on SiriusXM  co-hosts Professors Joseph Bankman and Richard Thompson Ford. 

California’s wildfire season started early again this year and its destruction already for the record books with the Dixie fire currently the second largest in the state’s history and growing while the Caldor fire has caused the evacuation of residents from the iconic  South Lake Tahoe  communities.  Here, Stanford Law School’s Professor Buzz Thompson, one of the country’s leading water law experts, discusses California’s wildfires, drought, water, and climate change  with  Stanford Legal  on SiriusXM  co-hosts Professors Joseph Bankman and Richard Thompson Ford. 

Bankman : Every year, those of us in the West are seeing smoke in our air from wildfires. And I think that’s true from the Pacific Ocean to east of the Rockies right now, isn’t it?

Thompson : Joe you’re absolutely right. We have in the western United States gone from the situation where droughts occurred once every 10 or 20 years, to a situation where we never seem to leave a drought for very long before we enter into it again. We used to talk about fire seasons, nowadays we talk about fire years because they last all year long.

Ford : And right now, the Dixie fire has burned more than 750,000 acres [as of August 29], taking hundreds of homes and businesses with it, and it’s only 35 percent contained. But the fires are connected to a larger phenomenon aren’t they? I mean, we’ve also had record high temperatures in places like Portland and Seattle, where no one owns an air conditioner. Are these things linked in some way?

Thompson : They’re definitely linked. The first thing I want to emphasize is that the Dixie fire is actually the second largest fire in the history of the state of California. The only fire that was bigger than that was the August Complex fire last year, which was over a million acres burned. And actually, last year in 2020, of the 10  largest wildfires in the history of the state of California, half of them—five—occurred in 2020 alone. And now you’re seeing with the Dixie fire that again it is the second largest fire. It’s, as you point out, already over 750,000 acres burned. It’s 35 percent contained at this point, which means it could easily take over the top spot from last year’s August Complex fire.

So, the first thing to recognize is that not only are things bad right now, but they are just far worse than what we have seen before. Second point is that the wildfires are part of just a much larger problem. And I would say that larger problem—you know, really, the ultimate problem— is climate change. And one of the things that we expect from climate change is that disastrous events—droughts, fires and the like—that may have occurred in the past, will occur more frequently in the future, and they will be even worse than they were. And that’s what we’re seeing with wild fires.

But climate change is also leading to another big problem, which is drought and lack of water. And that lack of water can also impact wildfires. In fact, it is a major cause of our wind fires.

Bankman : And Buzz, when we talk about drought, I mean, most of us think about how much rainfall we’ve had. And the last year we had, I think, only about half of what we usually get, if I’m right, depending on the location. The previous year was very light. We have had a cycle of light year, after light year, after light year, light rainfall that is. Is that climate change-related? How do we understand the cycles?

Thompson : Excellent question Joe. And let me first correct you. That last year was a dry year, so we’re in our second dry year. But if you actually go back to 2019, that was the wettest year in the state of California history. And if we had had an interview like this in 2019 I would have said that California is not in a state of drought, it’s a state of whiplash. And it really is. It’s a state where we can be in drought and then suddenly end up with floods, and then go back to droughts.

In the mid-19th century, there was a period of time when it rained in California and Oregon for about 45 days. And it rained so much that it flooded California. It created a lake in the middle of the central valley of California that was about 200 miles long and about 20 miles wide. It flooded the city of Sacramento. By that summer we were at the very beginning of what was known as the great civil war drought of 1862, which impacted the entire nation and was probably one of the worst droughts ever. So, it’s not just droughts we have, but it’s droughts with floods the following year. But this is absolutely what you would expect in the face of climate change. You’re expecting extremes, more extremes, and then more extreme extremes. The drought situation that we have right now, however, is one that we will continue to face, again broken up occasionally by floods. And those droughts are a major cause of, again, the wildfires that we’re seeing right now, as well as a large number of other problems.

Ford : So, not only has California historically been subject to lots of droughts and lots of flooding, but it’s getting worse because of climate change. In this very dramatic way, I’m wondering Buzz, what’s the relationship between all the fires that we’re seeing and new settlements in parts of the state where people didn’t used to live? Is that one of the factors as well contributing to the fires, or is it mainly climate change?

Thompson : I would separate the fire problem, Rich, into two parts. The first is that we are seeing larger fires today and longer wildfire seasons than we had in the past. That’s the result of probably two or three things. The first is that we have historically been suppressing our fires. The answer to fires in the 20th century, and you know this from the old Smokey the Bear advertisements that you used to see on TV or in comic books, was to suppress the fires and try to prevent the fires. But that led to a huge buildup in the fuels. You know, the old dead trees. Very thick forest areas. So that’s contributed to the fires being worse. In addition to that, we have climate change over the last several decades, and that climate change has also led to higher temperatures, more frequent and extreme droughts, and that’s led to tree die-off. So that also increases the fuels that can readily catch fire and spread the fire once that fire begins. So those are two major causes of larger fires, and then longer wildfire seasons.

In addition to that though, the wildfires that we have tend to be more destructive of human settlements, right? So, a fire by itself obviously can be problematic, but our real concern today is entire towns that burn up and displacing people, and all of the smoke that we have to breathe on a regular basis these days. And a lot of that comes from the fact that we haven’t really been doing our land use planning appropriate for the area that we live in. So, we tend to build our towns right in the forest. People love forests. I think it’s great to spend my vacations in forested areas. But a lot of people want to live in and actually build their houses there. Those houses, by the way, are also fuel. But, more importantly, it leads to those people who get displaced. And because, again, we love to live in the west, where we have grand vistas, that means that, unfortunately, we can end up having to breathe the air when these wildfires begin.

Ford : There just are so many causes it’s a little dispiriting.

Thompson : Well another way of looking at that is that we actually have a variety of ways of trying to deal with the problem. The one thing that’s hard to deal with immediately is the climate change. As the recent report by the Intergovernmental Panel on Climate Change noted, climate change is baked into our future, no matter what we do right now in terms of reducing carbon. And we should reduce carbon. It’s baked into our future. We’re going to have it, so we can’t do anything about that.

But we can eliminate a lot of that fuel that has built up by planning smaller prescribed burns in our forests. That’s what our Indigenous population did before we came along and started suppressing the fires. We can also engage in better land use. We can create the defensible spaces within our forest communities. We can have people move when their homes burn down rather than just building exactly where the first are going to occur again.

Bankman : When people live in these areas, they’ve got to bring electricity in. And it seems like a lot of these fires start because there’s a power line outage and we’ve got tens of thousands of miles of, I take it, exposed power lines around.

Thompson : Above ground energy infrastructure is a cause of a variety of fires. The fires are going to be worse than they otherwise would have been, but they are frequently created by those sparks or shortages that occur on the surface. And, in fact, the fire that we started out the show talking about—the Dixie fire—there’s some evidence that that might have been created by a circuit outage on July 13, which led to a blown fuse, and then a tree toppling, and then things catching fire. And one of the things that PG&E is working on—in fact, all of our major electricity utilities in the state of California are working on—is trying to move more and more things underground, and trying to improve the things that are above ground. We absolutely have to do that, but I also just want to emphasize, that costs money. And one of the reasons we frequently didn’t do it in the past was that groups like PG&E were afraid that if they ask for the money necessary to do all of that on a quick basis, they would have had a consumer revolt on their hands. So, we absolutely have to do that, but people have to be willing to spend the money in order to get that done.

Bankman : You know one thing that occurs to me, as you say this Buzz, is that it’s easy to beat up on a utility like PG&E, but ultimately it’s a question of money. And who’s going to pay for it? One interesting issue it raises is what do we do about someone who lives in a fire zone—the cost of making that electricity safe might be really huge. And do we make that person pay for it?

Thompson : I’m not going to make myself popular with communities in our forested foothills and mountains of California, but Joe, you’re absolutely right. It is ultimately a matter of economics and you need to send people the right signals. You should send them a signal at the very outset though, because that’s the easiest time to send people economic signal. To say ‘If you want to build out here, in the middle of nowhere, where, number one, you’re at greater risk. And second of all you’re going to be demanding electricity, and probably the cheapest easiest way to be building will be an above-ground power line. Okay, you can move out here, but here’s the cost you’re going to be imposing, and you should be paying for.’

The next question becomes, what if they’re out there already? Then what type of economic signals might you be able to send them that would be valuable? The Nature Conservancy has been working on ways of building fire breaks around some of these communities in California. And those fire breaks might also serve as parks that people can go to. What if we have a system where people get a discount on their fire insurance if the town invests in the big fire break recreational areas?  That’s an example of an economic signal that maybe people won’t be as upset about, because it would actually be a way of lowering their fire insurance costs.

Ford : Buzz, can you talk about a hot drought and how it may be different than the kind of droughts I remember as a kid living in the Central Valley, where occasionally we did have droughts and the farmers were upset about it. So, what’s a hot drought? And why is it more problematic for us in California?

Thompson : That’s a really good question, Rich. We’ve had droughts for centuries in the state of California, and if nothing had changed, we would have continued with that particular pattern. But what we are encountering more and more today is what’s known as a hot drought. In the past, droughts were not connected to a particularly warm year. You could have a drought and it could be a cold year. In the future, all of our droughts are going to be in years that are warmer than they’ve historically been. And that poses a wide variety of problems. In particular, it means that even if we have the same level of precipitation as we had before, less of that actually gets to a river or stream.

The first problem in the western United States that we have with a hot droughts, is that we depend upon our snowpack. All the snow, for example, up on the Sierra mountains, is a natural reservoir for us. We need water in summer and the fall when it’s not going to rain. In the past, that snowpack would melt over time, we could capture it, and we could use it during the time when there wasn’t precipitation. Again, that snowpack is a natural reservoir. Now, that snowpack is disappearing. In drought years now, there is virtually no snow up there, so we’ve effectively eliminated that natural reservoir.

Equally importantly, you have drier soil, so that, when it does rain, what little rain you get during a drought gets absorbed by the soil. Because it’s hotter, you also have higher evaporation. So, in a surface reservoir, more of that actually evaporates.

There is a situation that we are now seeing where snow sublimates, a term which, at best five years ago, I had never heard of. With sublimation, snow goes from the solid state to the gaseous state without ever melting. So, we lose water that way. And then, finally, the plants have higher transpiration rates. That means that we also get those plants absorbing more water and now in the central Valley, where we have all the farmers who are trying to grow crops, they need more water than they needed before. So, all of that means that, no matter what level of precipitation we have, we’re in just much worse shape than we were before.

Bankman : Wow. This is all so sobering. And we talked about wildfires as the problem that we tie to drought. But actually Buzz, there are lots of problems that are tied to drought aren’t there?

Thompson : Absolutely true—there are multiple problems. So, first thing is in a drought, none of us are able to get the water that we normally use. Right now, for example, in California, Governor Newsom has asked all of us to voluntarily cut back on water use by 15 percent. We can do that. It’s an inconvenience, but we can do that. In much worse shape are the farms, because it’s very difficult for the farmers to cut back and then continue to grow the crops that we need. And yet the farmers in the central valley right now are getting virtually none of the surface water that they would historically receive.

And then you also have to worry about energy production. Hydro power is a major energy producer and yet, as our reservoirs lose water, those reservoirs get down to a level where it is impossible to continue to produce hydro power. Best example is Oroville. That’s one of our biggest dams in California and it got hit for the first time ever in its 50 years. It has gone down to a level that we had to shut down the power plant. The amount of hydro power we produced in 2020, which Joe you mentioned earlier, was a dry year, it actually was a little more than half of what it would have been the year before. And that’s drought related.

Bankman : One thing that one of our terrific students here,  Leehi Yona , JD/PhD ’23, has been researching is that how fires themselves contribute a lot of pollution back into the air.

Thompson : That’s absolutely right. And you’re right about Lee. She is a truly brilliant student and she’s actually getting both her law degree and her PhD from Stanford at the same time. But, as she has emphasized in her work, we have what’s known as a positive feedback loop. We have a situation as we’ve discussed already, as a result of climate change we’re getting more wildfires. When those wildfires burn the trees, those trees release that carbon dioxide, and that carbon dioxide then contributes further to climate change. So, you have again, a circular positive feedback loop, where, particularly when you realize this isn’t just happening here, it’s happening throughout the world. We are seeing climate change create problems that intensify climate change. The interesting thing that Lee is also doing is trying to determine the level of those emissions from our wildfires. But interestingly, although California tries to account for its greenhouse gases and how we can deal with them, California doesn’t count that. And so, she’s also looking at how we could better account for those greenhouse gas emissions resulting from wildfires.

Ford : Can you offer us some more ways out of this? We talked about doing things to limit wildfires. Do you have any other thoughts about even partial solutions for us?

Thompson : So, we could take each of these individual problems and talk about how to solve them. But let’s just talk about the wildfires. We’ve already talked about prescribed burns. We’ve talked about changing our land use. We’ve talked about how we might be able to use insurance premiums to actually send people the correct information. One thing that I was talking to someone about the other day is, we also have the sort of odd situation where we have a lot of our prisoners in California going out and fighting fires. But unfortunately, under California law, a lot of those prisoners when they get released from prison, cannot be firefighters or cannot have particular firefighting positions because they are felons. And one of the things we need to do is to change our law. We already began changing last year. There was a good piece of legislation that came down last year to actually give those former prisoners who have been trained in prison to be firefighters good jobs out on the fire lines. But that just shows when you get into this, you get into everything. You even get into our prison policy and employment.

Ford : It’s just there’s so many issues here and it’s fascinating. It’s also very sobering. Thank you so much Buzz for coming to talk to us about these issues today, and thank you to our audience for joining us here on Stanford Legal on Sirius XM.

Thompson : Thank you Rich, thank you Joe. It’s always a pleasure.

A global expert on water and natural resources,  Barton “Buzz” Thompson , JD/MBA ’76 (BA ’72) focuses on how to improve resource management through legal, institutional, and technological innovation. He served as Special Master for the United States Supreme Court in Montana v. Wyoming, an interstate water dispute involving the Yellowstone River system.  He also is a former member of the Science Advisory Board of the United States Environmental Protection Agency.   He chairs the boards of the Resources Legacy Fund and the Stanford Habitat Conservation Board, is a California trustee of The Nature Conservancy, and is a board member of the American Farmland Trust, the Sonoran Institute, and the Santa Lucia Conservancy.

The science behind the West Coast fires

A collection of research and insights from Stanford experts on wildfires' links to climate change, the health impacts of smoke, and promising strategies for preventing huge blazes and mitigating risks.

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Barton Thompson Stanford Law School [email protected]

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Articles on California wildfires

Displaying 1 - 20 of 21 articles.

The wildfires that led to mass extinction: a warning from California’s Ice Age history – podcast

Gemma Ware , The Conversation

Western wildfires destroyed 246% more homes and buildings over the past decade – fire scientists explain what’s changing

Philip Higuera , University of Montana ; Jennifer Balch , University of Colorado Boulder ; Maxwell Cook , University of Colorado Boulder , and Natasha Stavros , University of Colorado Boulder

When hotter and drier means more – but eventually less – wildfire

Maureen C Kennedy , University of Washington ; Don McKenzie , University of Washington , and Jeremy Littell , US Geological Survey

Trees are dying of thirst in the Western drought – here’s what’s going on inside their veins

Daniel Johnson , University of Georgia and Raquel Partelli Feltrin , University of British Columbia

Another dangerous fire season is looming in the Western U.S., and the drought-stricken region is headed for a water crisis

Mojtaba Sadegh , Boise State University ; Amir AghaKouchak , University of California, Irvine , and John Abatzoglou , University of California, Merced

2020 was a terrible year for climate disasters, but there are reasons for hope in 2021

Matthew Hoffmann , University of Toronto

Restoring California’s forests to reduce wildfire risks will take time, billions of dollars and a broad commitment

Roger Bales , University of California, Merced and Martha Conklin , University of California, Merced

Birthdays, holidays, Christmas without mum or dad: how to support kids with a parent away fighting fires

Marg Rogers , University of New England

California wildfires: why a gender-reveal party got the blame, but shouldn’t have

Doug Specht , University of Westminster

Coping with Western wildfires: 5 essential reads

Jennifer Weeks , The Conversation

California is on fire. From across the Pacific, Australians watch on and buckle up

David Bowman , University of Tasmania and Ross Bradstock , University of Wollongong

What the battle over control of PG&E means for US utility customers

Theodore J. Kury , University of Florida

Making life-or -death decisions is very hard – here’s how we’ve taught people to do it better

Laurence Alison , University of Liverpool and Neil Shortland , UMass Lowell

California wildfires signal the arrival of a planetary fire age

Stephen Pyne , Arizona State University

What western states can learn from Native American wildfire management strategies

Kari Marie Norgaard , University of Oregon and Sara Worl , University of Oregon

Planned burns can reduce wildfire risks, but expanding use of ‘good fire’ isn’t easy

Courtney Schultz , Colorado State University ; Cassandra Moseley , University of Oregon , and Heidi Huber-Stearns , University of Oregon

Disasters and disagreements: Climate change collides with Trump’s border wall

Korey Pasch , Queen's University, Ontario

Using archaeology to understand the past, present, future of climate change

Andrew Roddick , McMaster University

Better forest management won’t end wildfires, but it can reduce the risks – here’s how

Courtney Schultz , Colorado State University and Cassandra Moseley , University of Oregon

We can’t stop wildfires – we need to relearn how to live with them

Andrew Scott , Royal Holloway University of London

Related Topics

• Climate change
• Forest Management
• Natural disasters

Top contributors

Associate Professor of Forest and Natural Resource Policy, Colorado State University

Sr. Associate Vice President for Research and Research Professor, University of Oregon

Director of the Centre for Critical and Major Incident Psychology, University of Liverpool

Distinguished Professor of Engineering, University of California, Merced

Professor of Political Science and Co-Director of Environmental Governance Lab, University of Toronto

Director of Energy Studies, University of Florida

PhD Candidate in Political Science and International Relations, Queen's University, Ontario

Emeritus Professor of Life Sciences, Arizona State University

Associate Professor of Anthropology, McMaster University

Fellow, Queen's Institute for Energy and Environmental Policy, School of Policy Studies, Queen's University, Ontario

Professor of Pyrogeography and Fire Science, University of Tasmania

Assistant Research Professor and Director, Institute for a Sustainable Environment, University of Oregon

Reader in Cultural Geography and Communications, University of Westminster

Professor of Civil & Environmental Engineering and Earth System Science, University of California, Irvine

Emeritus professor, University of Wollongong

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Yale Climate Connections

The many ways climate change worsens California wildfires

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California has been ravaged by record wildfires in recent years. 2017 was the state’s costliest and most destructive fire season on record . The Mendocino wildfire in July 2018 was California’s largest-ever by a whopping 60 percent.

Even though California’s wildfire season has traditionally ended in October, the Camp Fire raging in November 2018 is the state’s most destructive on record.

The data tell the story: Six of California’s ten most destructive wildfires on record have now struck in just the past three years .

President Trump’s tweets suggesting forest mismanagement is to blame for California’s wildfire woes, and threatening to withhold federal funding , have prompted widespread rebukes for their insensitivity as thousands of citizens flee the fires – some, tragically, unsuccessfully – and as an affront to thousands of weary firefighters.

The reality is that about 57 percent of the state’s forests are owned and managed by the federal government , and another 40 percent by families, companies, and Native American tribes. Forest management does play some role in creating wildfire fuel, but some wildfires aren’t even located in forests. Moreover, scientific evidence clearly shows that climate change is exacerbating California’s wildfires in different ways:

• Higher temperatures dry out vegetation and soil, creating more wildfire fuel.
• Climate change is shortening the California rainy season, thus extending the fire season.
• Climate change is also shifting the Santa Ana winds that fan particularly dangerous wildfires in Southern California.
• The warming atmosphere is slowing the jet stream, leading to more California heat waves and high-pressure ridges in the Pacific. Those ridges deflect from the state some storms that would otherwise bring much-needed moisture to slow the spread of fires.

The Golden State’s hotter, drier conditions

Global warming causes higher temperatures, and 2014 through 2018 have been California’s five hottest years on record. This pattern leads to an increase in evapotranspiration – the combination of evaporation and transpiration transferring more moisture from land and water surfaces and plants to the atmosphere. Essentially, global warming causes plants and soil to dry out as the atmosphere holds more water vapor.

On top of this direct drying effect, climate change is causing a shift in rain patterns. Northern California has received only one inch of rain this season, which is about one-fifth of normal . A 2018 paper published in Nature Climate Change , led by UCLA’s Daniel Swain, found that as a result of global warming, California’s rainy season will become increasingly concentrated in the winter months between December and February. April, May, September, October, and November will become increasingly dry, meaning that the state’s wildfire season will start earlier and end later. As Swain noted in an informative Twitter thread about California’s November 2018 wildfires,

If Northern California had received anywhere near the typical amount of autumn precipitation this year (around 4-5 in. of rain near #CampFire point of origin), explosive fire behavior & stunning tragedy in #Paradise would almost certainly not have occurred.

With these hotter, drier conditions extending late into the year, wildfires have become larger, and they spread faster, cause more damage, and are more difficult to contain.

In Southern California, Santa Ana winds coming later in year

In a 2006 paper published in Geophysical Research letters , Berkeley scientists Norman Miller and Nicole Schlegel predicted that global warming would push the Southern California fire season associated with Santa Ana winds into the winter months. Those Santa Ana fires are especially costly because of the speed at which they spread due to the winds and because of their proximity to urban areas. The November 2018 Woolsey fire around Malibu and Thousand Oaks, California, is a tragic example.

Researchers of a 2015 study published in Environmental Research Letters , led by Yufang Jin at UC Davis, forecast that the area burned by Southern California wildfires will increase by about 70 percent by mid-century as a result of the drier, hotter, windier conditions caused by global warming. And these Southern California wildfires often occur outside of forests , according to the president of the Pasadena Fire Association.

Connections to the Arctic and jet stream

Rutgers climate scientist Jennifer Francis over the past decade has been researching the connection between changes in the Arctic and extreme weather patterns throughout the Northern Hemisphere. In recent years a growing number of climate scientists have found evidence supporting her groundbreaking research.

The Northern Hemisphere jet stream is a result of the temperature difference between the cold Arctic and warmer lower latitudes in regions like North America and Europe. But the Arctic is the fastest-warming region on Earth, largely because as reflective sea ice disappears , the Arctic surface is increasingly covered by dark oceans that absorb more sunlight. The rapidly-warming Arctic is shrinking the temperature difference between that region and the lower latitudes, which in turn weakens the jet stream. As a result, rather than a fast-moving flow of air, the jet stream increasingly is taking a slow, meandering path across the Northern Hemisphere.

In between these jet stream waves, weather patterns have a tendency to stall in place. These patterns include heat waves, the polar vortex, hurricanes and associated record rainfall, and high-pressure ridges, and the latter has tended to occur off the California coast. During the drought of 2012 to 2016 – California’s worst in over a millennium – a high-pressure ridge in the Pacific was so persistent, that Swain coined it the “ Ridiculously Resilient Ridge .” A similar system has formed off the coast in late 2018:

These high-pressure ridges divert storm systems around California, leading to the lack of rainfall in the state during these dry spells. In a 2017 paper in Nature Communications , researchers led by Ivana Cvijanovic and Ben Santer found still more evidence of a connection between disappearing Arctic sea ice and these high-pressure ridges in the Pacific. And in an October 2018 paper in Science Advances , scientists Michael Mann and Stefan Rahmstorf and colleagues found that depending on how human fossil fuel pollution changes in the coming years, the frequency of wavy jet stream events could triple by the end of the century.

Clear evidence of wildfire-climate connection

Climate scientists have identified numerous ways in which human-caused global warming is exacerbating California wildfires. A 2015 special report in the Bulletin of the American Meteorological Society found that “An increase in fire risk in California is attributable to human-induced climate change.” And a 2016 study in the Proceedings of the National Academy of Sciences found that human-caused global warming doubled the area burned by wildfires in the western U.S. over just the past 30 years.

That’s an inconvenient conclusion for those who want to maintain a “business as usual” approach to the use of fossil fuels. And also to those favoring the President’s suggestion that California’s wildfire troubles can largely be solved just by adjusting forest management, or his recent 60 Minutes TV view that “ it’ll change back again .”

The reality is that the more global warming humanity causes, the worse California’s wildfires will become.

Editor’s note:  We welcome this article as the first of a monthly series of reports by new Yale Climate Connections regular contributor Dana Nuccitelli.

Dana Nuccitelli

Dana Nuccitelli, research coordinator for the nonprofit Citizens' Climate Lobby, is an environmental scientist, writer, and author of 'Climatology versus Pseudoscience,' published in 2015. He has published... More by Dana Nuccitelli

California Wildfires: The Issue of the Proper Communication Essay

• To find inspiration for your paper and overcome writer’s block
• As a source of information (ensure proper referencing)
• As a template for you assignment

Introduction

Executive summary, key stake holders and supporting figures or organizations, recommendations.

Between 2017 and 2019, the state of California witnessed a sequence of ravaging wildfires that cumulatively resulted in residents’ compelled evacuation. Albeit California state and local fire departments, as well as other stakeholders, tried to contain this incident, their resources were substantially limited. Various analytical studies point to several areas where inadequacies such as infrastructure and communication were noticeable. The paper presents an in-depth case study analysis related to the incident mentioned above.

In 2017 October, an assortment of massive and rapidly-spreading wildfires began in Northern California, particularly in Solano, Napa, and Sonoma Counties, resulting in one of the most life-threatening wildfire catastrophes the state has ever witnessed. Cumulatively, the three major fires destroyed over 140,000 acres, demanded emergency relocation of an estimated 100,000 persons, and triggered losses of approximately 15 billion dollars, and 44 deaths (Serna, 2018). The fires broke out in rapid succession, thereby overwhelming the emergency response teams and the available fire response equipment. The 2018 Camp Fire, which severely damaged Butte County and Paradise Town, burnt a cumulative 153,336 acres, demanded a rapid evacuation of 52,000 people, and resulted in 85 fatalities (Serna, 2018). Other wildfires like the 2018 Woolsey, Hill, and Saddle Ridge fires are just other pointers of the wildfire threats in California that resulted in considerable losses and fatalities.

Given the rapid acceleration of the wildfires, many residents found themselves in emergently- precarious situations, particularly at night, with a minimal window of time for evacuation. The phenomenon mentioned above yielded two primary identifiable issues: stress on public resources and infrastructure, transport and shelter, and considerably low levels of preparedness by emergency management agencies throughout the state. Cumulative estimates reveal that the catastrophic fires during the period between 2017 and 2019 forced over one million citizens to depart their residences (Wong et al., 2020). For holistic and effective interventions during such life-threatening disasters like wildfire, it is compelling that response models be reconstructed with informative retrospect to avoid future recurrences of the poor evacuations witnessed before.

The main identifiable primary stakeholders in the California wildfires and any other wildfire emergencies for that matter:

• The Fire Department
• The Transport Department; Public and private
• The Police department
• The Telecommunication department
• The Community
• Volunteer groups; individuals and organizations

Cross-state wildfire analyses and comparisons of California wildfires point to one crucial issue at the cause level, which seems viably potential to recur in the future. Comprehensive evidence revealed that wildfires are primarily started either directly or indirectly by human activities, for instance, car ignition sparks and human-electrical faults, among others (Wong et al., 2020). At the evacuation level, broader findings pointed at three critical items—first, inadequate resources, especially within the emergency response departments. Nearly every unit did not have sufficient public resources for the effective and swift transfer of the whole threatened population during these catastrophes (Wong et al., 2020). There were also indications that several agencies- within California and at the national level – are not adequately equipped to evacuate vulnerable persons lacking the means and ability to safeguard themselves during disasters.

Second, areas with difficult-accessible roads significantly impaired the smooth and swift evacuation processes. According to Wong et al. (2020), neighborhoods with solitary exits and highly-debrided streets significantly impacted the clearance procedures by triggering congestion. Clogging was also exacerbated by people’s preference to evacuate with their vehicles instead of a public means (Wong et al., 2020). Third, with regards to communication, the department had a myriad of alternatives to adopt, albeit not all options were exhausted. The impact was that inadequate communication was substantially witnessed in several Californian wildfires (Wong et al., 2020). A combination of these inefficiencies resulted in substandard evacuation approaches and considerable losses that arguably would have been averted.

Each of the identified stakeholders had an instrumental role in facilitating the swift and effective emergency evacuation during the wildfires to mitigate the total realizable risks from the disaster. However, these responsibilities were not manipulated exhaustively to ensure people’s overall safety. To improve future emergency responses during such calamities, several new models are recommendable. First, the state and local jurisdictions should assess or evaluate the longitudinal impact of historical fires and establish patterns; this will help distinguish the vulnerability of localities, in effect, mark them as vulnerable and deploy significantly adequate emergency resources within convenient vicinities. Cross-state longitudinal evaluations can aid in identifying gaps in infrastructure and other critical items necessary for emergency evacuations.

Second, there is a need to explore the most comprehensive communication media available to the residents. During this era of technological robustness, a myriad of avenues should be available for communication with citizens, especially during emergency disasters. Third, the community should be widely educated on the adverse impacts of wildfires and taught fundamental response measures. During this period of sharing economies, there are many options to address issues like shelter and transport through applications such as Uber and Lyft, or Airbnb. Such items could significantly address the issue of transportation and settlement of evacuated persons.

Wildfires pose a significant threat to the economic welfare and lives of many communities. In particular, California has witnessed severe damages and incurred substantial losses from wildfires, especially between 2017 and 2019. Nonetheless, evidence points to the state’s continued lack of adequate preparedness to combat such recurrent emergencies. In this era of technological advancements, several strategies that aim to facilitate aspects such as proper communication and timely emergency response should be implemented to prevent the adverse impacts of these disasters.

Wong, S. D., Broader, J. C., & Shaheen, S. A. (2020 ). Review of California wildfire evacuations from 2017 to 2019 [PDF document]. UC Office of the President: University of California Institute of Transportation Studies.

Serna, J. (2018). Without warning: Redding fire moved faster than evacuation orders, leaving a deadly toll . Los Angeles Times.

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IvyPanda. (2022, June 17). California Wildfires: The Issue of the Proper Communication. https://ivypanda.com/essays/california-wildfires-the-issue-of-the-proper-communication/

"California Wildfires: The Issue of the Proper Communication." IvyPanda , 17 June 2022, ivypanda.com/essays/california-wildfires-the-issue-of-the-proper-communication/.

IvyPanda . (2022) 'California Wildfires: The Issue of the Proper Communication'. 17 June.

IvyPanda . 2022. "California Wildfires: The Issue of the Proper Communication." June 17, 2022. https://ivypanda.com/essays/california-wildfires-the-issue-of-the-proper-communication/.

1. IvyPanda . "California Wildfires: The Issue of the Proper Communication." June 17, 2022. https://ivypanda.com/essays/california-wildfires-the-issue-of-the-proper-communication/.

Bibliography

IvyPanda . "California Wildfires: The Issue of the Proper Communication." June 17, 2022. https://ivypanda.com/essays/california-wildfires-the-issue-of-the-proper-communication/.

October 29, 2020

Climate Change Is Central to California’s Wildfires

Conservative pundits who tout land management as the main issue fail to see the big picture

By Rebecca Miller , Katharine Mach & Chris Field

Kyle Grillot Getty Images

As the toll from California’s wildfires grows higher year after year, the state’s future appears fiery and hazy with smoke. For conservative columnists like Ben Shapiro , Niall Ferguson and Tyler O’Neil , it’s clear who is responsible: California Democrats. In recent opinion pieces, they acknowledge that climate change might play a role in these fires, but they blame Democratic leadership for exacerbating fuel buildups through poor land management. As proof, they reference a study from early this year in Nature Sustainability .

We wrote that study. These columnists are wrong.

Their opinion pieces represent a dangerous form of climate denialism, one that recognizes the value of climate adaptation—adapting to life under a changing climate—but purposefully misdirects by refusing to acknowledge the critical importance of limiting the amount of future climate change.

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The science is clear. Climate change plays an undeniable role in the unprecedented wildfires of recent years. More than half of the acres burned each year in the western United States can be attributed to climate change. The number of dry, warm, and windy autumn days—perfect wildfire weather—in California has more than doubled since the 1980s.

Without aggressive reduction of greenhouse gasses, forests in Northern California, Oregon and Washington could experience an increase of more than 78 percent in area burned by 2050. Governor Gavin Newsom correctly characterized recent wildfires as a “climate damn emergency.” It’s almost unfathomable to imagine a situation in which the 2020 wildfire season becomes a regular occurrence or even a mild year, but that’s exactly what could happen in our future.

We must dramatically reduce our greenhouse gas emissions. Otherwise, in a few decades, we might recall the more than four million acres of California burned so far this year—that have already shattered the prior record, set in 2018—as a relatively light wildfire season. That prospect, rooted in science and devastating to life and property, is unacceptable.

But we must also prepare for reality with strong measures to reduce our already heightened and increasing risk. Resilience will require a broad portfolio of actions, from the household to the federal level, from emergency preparedness to disaster-resistant building codes. For wildfires, fuel treatments like prescribed burns have become a salient example.

Fuel treatments reduce the buildup of vegetation that has resulted from nearly a century of fire suppression and from the criminalization of traditional Indigenous controlled burning . Twenty million acres of forests across California could now benefit from fuel treatments like prescribed burns, purposely-set fires intended to safely reduce fuel overgrowth. However, inadequate funding, limited prescribed burn crews, and dangerous weather conditions remain barriers to conducting prescribed burns.

As the owner of 57 percent of forests in California, the federal government has an enormous role to play. The U.S. Forest Service aspires to treat 500,000 acres per year, but is unlikely to reach that target given limited funding from Congress. However, new legislation could help: a new bill from Ron Wyden (D–Ore.) could guarantee $600 million each year for prescribed burns across federal, state and private lands.

Meanwhile, legislators in Sacramento have passed dozens of bills to address wildfire risk in the last few years, including six new laws on prescribed burns. These laws and recent executive actions address several of the barriers we found in our study, including the need for liability protection and programs for training and public education. Last year, Governor Newsom also declared a state of emergency to fast-track 35 fuel-reduction projects that would protect 200 at-risk communities.

But fuel treatments alone are not the solution; we cannot disregard that our contributions to climate change continue to aggravate our risk. Reducing greenhouse gas emissions is an essential part of protecting our communities and ecosystems in the future. By exclusively focusing on fuel treatments, these conservative columnists ignore the ongoing influence of climate change and politicize critical action for fuel treatments that protect our communities and ecosystems.

In the September 29 debate, two years after recommending that Californians rake the forest , President Trump deflected on commenting on the role of climate change in recent wildfires. Instead, he told us, “Every year I get the call: ‘California is burning! California is burning!” If that was cleaned, if you had good forest management, you wouldn’t be getting those calls.”

Ignoring climate change won’t prevent climate disasters. From California wildfires to Gulf Coast floods, we already experience their effects. Arguments that purposefully misconstrue the impacts of climate change on our ecosystems and communities increase our peril.

Home — Essay Samples — Environment — Wildfires — Worsening California’s Wildfires: Climate Change

Worsening California's Wildfires: Climate Change

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Post fire becomes California’s largest wildfire of the year

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A major wildfire in northern Los Angeles County continued burning Monday evening southeast toward Pyramid Lake, scorching more than 15,000 acres to become the state’s largest blaze of the year.

The Post fire was 15,611 acres as of 7:34 p.m. Monday and 20% contained. It was burning in steep, hard-to-reach areas and threatening homes as well as infrastructure, including power lines, dams and oil pipelines, officials said in a status update on the California Department of Forestry and Fire Protection’s website.

Officials cautioned Monday evening that heavy smoke from the Post fire might make it difficult for drivers to see on the 5 Freeway south of Gorman and north of Santa Clarita. Residents in communities including Castaic, Piru and Santa Clarita will likely notice the smoke as well.

Firefighters will focus much of their attention on building and reinforcing fire lines around the perimeter while helicopters and air tankers try to slow down the fire’s advance and douse hot spots as conditions allow, officials said in their update.

L.A. County officials said high temperatures and low humidity were expected Tuesday, a bad combination for firefighters attempting to snuff out flames as the fire chews through vegetation dried out by the heat and lack of moisture in the air. Wind gusts may reach up to 55 mph, further complicating firefighting efforts.

If northeast winds intensify, the Post fire might be pushed deeper into the forest and wilderness areas. This could cause the fire to spot up to three-quarters of a mile away — meaning small pieces of burning leaves and grass could travel that distance and start small fires farther away from the fire line, fire officials said .

“Conditions have continued to support the rapid spread of the wildfire,” said Ariel Cohen, a National Weather Service meteorologist in Oxnard.

Red flag warnings, which are alerts for dangerous fire conditions, were in effect for the area through at least Tuesday evening as the air was expected to dry out during the day and temperatures were expected to rise.

Such severe warnings have also been issued across large swaths of inland California, with the alerts forecasting winds that carry “the potential for rapid fire spread,” from the northern Sacramento Valley through the Antelope Valley.

Since Saturday, more than 20 fires sparked across California, burning over 20,000 acres, the majority of which were still not fully contained Monday, according to the Cal Fire website . Several triggered evacuations and damaged buildings, including the Post fire.

There had been predictions for a subdued start for the state’s wildfire season this year, given a series of late-season, moisture-heavy storms, but this new spate of fires heightened concerns.

“It’s pretty early and this is [a] pretty large fire,” Los Angeles County Fire Department spokesperson Craig Little said of the Post fire. “We can always hope, but I’m thinking there’s going to be more of this in the future for the summer. ... It’s very early for a fire of this magnitude.”

Such early-season fires are fueled by heat-dried grasses, and Southern California’s hillsides and mountains are dense with vegetation after two back-to-back wet winters. Because of that, more dangerous fires that engulf larger trees and plants are likely in store for later this year, according to Daniel Swain, a climate scientist with UCLA.

“We could, in fact, see a very active finish to fire season 2024, but we aren’t there yet, despite the current activity level,” Swain said during a briefing Monday . “This is not yet indicative of really active conditions.”

In particular, the forested, high-elevation areas that have endured some of the state’s worst wildfires in recent memory are still moist following two strong wet seasons and haven’t yet started to display much wildfire activity.

That could change as conditions get hotter and drier for longer stretches of time, Swain said. Those areas will likely start drying out in July at lower elevations and August at higher elevations, with fire activity possibly lasting longer than usual due to two years of vegetation build-up.

“Expect September — and maybe even October and parts of November in some areas — to feature very active fire conditions this season,” Swain said, adding that blazes that ignite later in the season could become increasingly intense.

The fires that ignited over the past weekend are likely a foreshadowing of what’s to come.

The Post fire on Saturday forced about 1,200 people to evacuate from the Hungry Valley Park and Pyramid Lake areas, not far from the 5 Freeway, according to firefighters.

On Monday, officials also ordered areas south of Pyramid Lake to be evacuated, including the Oak Flats Campground. An evacuation warning was also issued for Paradise Ranch Estates.

The fire has destroyed an auto shop and threatened dozens of other buildings. One person has been injured, Little said.

The mountainous terrain has forced the firefighting effort to rely more heavily on air crews — 24 helicopters and multiple air tankers, as of Monday evening — but high winds have made water drops less effective, Little said.

Almost 1,700 firefighters and other personnel continued to battle the flames Monday. The Ventura County Fire Department and U.S. Forest Service were aiding in the effort. The Post fire’s cause remains under investigation.

Also in Southern California, about 1,100 acres had been burned by the Hesperia fire in San Bernardino County, prompting road closures and an evacuation warning . The fire was 72% contained as of Monday evening, according to Cal Fire and the San Bernardino County Fire Department .

The Tuscany fire ignited Monday and burned 350 acres in Palm Springs, according to local officials. As of Monday evening, it was 50% contained, according to Cal Fire.

Multiple fires also burned across Northern California.

In Sonoma County, the Point fire burned more than 1,200 acres and several structures south of Lake Sonoma. It was 20% contained Monday evening, according to Cal Fire, after starting Sunday afternoon.

The Sites fire, burning northwest of Sacramento in Colusa County, started Monday afternoon and erupted to almost 4,500 acres by the evening. Firefighters had been unable to contain it, hampered by hot dry conditions, officials said.

And southeast of Sacramento, the Aero fire started Monday afternoon in Calaveras County and had already burned more than 5,000 acres by about 10 p.m. and had no containment, according to Cal Fire.

As Swain took stock of the current fires, he noted that the rest of the season could be affected by a number of other factors, including the current transition from the El Niño weather pattern to La Niña .

La Niña is associated with drier conditions along the West Coast and in Southern California in particular. La Niña was last in place during the state’s three driest years on record, 2020 through 2022, which also saw the state’s biggest wildfire seasons on record .

Climate change is also driving warmer global temperatures and a thirstier atmosphere, both of which can extract more water from the landscape and pave the way for hotter and faster fires in the West and other arid areas, Swain said.

What’s more, the upcoming Fourth of July holiday is often linked to wildfire ignitions, and there is potential for that pattern to repeat this year, he added.

“The good news is increasingly in the rearview mirror,” Swain said. “As these conditions continue to rapidly warm up, dry out and get windier, the bad news is that I think that the back half of this season is going to be much more active — with a lot more concerning level of wildfire activity in a lot of areas — than the first half.”

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June 17, 2024

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Grace Toohey is a reporter at the Los Angeles Times covering breaking news for the Fast Break Desk. Before joining the newsroom in 2022, she covered criminal justice issues at the Orlando Sentinel and the Advocate in Baton Rouge. Toohey is a Maryland native and proud Terp.

Hayley Smith is an environment reporter for the Los Angeles Times, where she covers the many ways climate change is reshaping life in California, including drought, floods, wildfires and deadly heat.

Joseph Serna is a deputy editor on the Fast Break team at the Los Angeles Times and helps oversee daily breaking news coverage.

Jaclyn Cosgrove covers the (great!) outdoors at the Los Angeles Times. They started at The Times in 2017 and have written about wildfires, culture, protests, crime and county government. In 2022, they managed For Your Mind, a yearlong mental health project. Cosgrove is originally from rural Oklahoma and is a proud Oklahoma State University graduate. They fell in love with the Southern California landscape when they moved here in 2017. They are always looking for the next adventure and welcome your ideas. If their phone goes straight to voicemail when you call, it probably means they’re in the mountains with their beloved dog, Maggie May.

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Firefighters gaining ground in Southern California wildfire but strong, dry winds coming

LOS ANGELES (AP) — Firefighters have increased their containment of a large wildfire that is burning in steep, hard-to-reach areas and threatening critical infrastructure in mountains north of Los Angeles, officials said. But hot, dry, windy weather could challenge their efforts Tuesday.

The Post Fire was 20% contained Monday night after wind caused explosive growth over the weekend along Interstate 5, the main north-south route on the West Coast.

“Fire weather conditions are making it difficult to control the fire,” the Los Angeles County Fire Department said in a Monday night update. “Important structures like power lines, dams, and oil pipelines are at risk.”

READ MORE: This year’s summer of climate extremes hits wealthier places

Strong winds from the north mean the fire is expected to keep moving south, the department said. High temperatures and low humidity were forecast for Tuesday. Wind gusts could reach 55 mph (88 kph).

Officials had earlier warned residents of Castaic, home to about 19,000 people, that they should prepare to leave if the fire pushed south.

The fire scorched more than 24 square miles (61 square kilometers) and forced the evacuation Saturday of at least 1,200 campers, off-roaders and hikers from the Hungry Valley recreation area.

The fire erupted Saturday afternoon near I-5 in Gorman. Two structures burned within the evacuated recreation area.

The majority of the more than 1,000 firefighters assigned to the blaze were focused on its southern edge, near popular Pyramid Lake, which was closed as a precaution on Sunday and Monday.

The fire broke out as weather turned hot and windy in a region where grasses brought by a rainy winter have now dried out and become fuel.

Smoke has drifted eastward, causing a slight haze in the Las Vegas area. Officials there advised children, older adults, and people with respiratory and heart disease to stay indoors.

About 75 miles (120 kilometers) to the east, the nearly 2-square-mile (5-square-kilometer) Hesperia Fire was more than 70% contained by Monday night. The fire erupted Saturday and forced road closures and evacuation warnings in San Bernardino County.

In Northern California’s Calaveras County, a new fire, the Aero Fire, burned nearly 8 square miles (20 square kilometers) and led to evacuation orders for some residents, officials said.

And about 150 miles to the northwest, a wildfire in a sparsely populated area near Lake Sonoma was 20% surrounded Monday after charring nearly 2 square miles (5 square kilometers).

After back-to-back wet winters, fire season has gotten off to a slow to near-average start, said Daniel Swain, a climate scientist with the University of California, Los Angeles.

“These are not peak season fires either in scope or behavior, or in terms of where they’re burning,” Swain said in an online briefing. “In many ways, they’re classic, early-season fires since they’re primarily burning in grass and brush.”

Swain said he expects more fire activity to begin in July at lower elevations and August at higher elevations.

“And the bad news is that I think that the back half of this season is going to be much more active, with a lot more concerning level of wildfire activity in a lot of areas than the first half,” he said.

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Large wildfires create weather that favors more fire

Smoke traps sunlight, makes days warmer, drier

A new UC Riverside study shows soot from large wildfires in California traps sunlight, making days warmer and drier than they ought to be.

 Many studies look at the effect of climate change on wildfires. However, this study sought to understand the reverse — whether large fires are also changing the climate. 

“I wanted to learn how the weather is affected by aerosols emitted by wildfires as they’re burning,” said lead study author and UCR doctoral candidate James Gomez.

To find his answers, Gomez analyzed peak fire days and emissions from every fire season over the past 20 years. Of these fire days, he examined a subset that occurred when temperatures were lower, and humidity was higher. “I looked at abnormally cool or wet days during fire season, both with and without fires. This mostly takes out the fire weather effects,” Gomez said. 

Published in the journal Atmospheric Chemistry and Physics, the study found that large fires did have an effect. They made it hotter and drier than usual on the days the fires burned. The extra heat and aridity may then make conditions favorable for more fire. 

“It appears these fires are creating their own fire weather,” Gomez said. 

The most intense fires occurred in Northern California, where fire-fueling vegetation is denser than elsewhere in the state. On average, temperatures were about 1 degree Celsius warmer per day during the fires. 

There are likely two reasons for this. One — soot traps heat, and two —the extra heat reduces humidity in the atmosphere, making it more difficult for clouds to form.

“Fires emit smoke with black carbon, or soot. Since it is very dark, the soot absorbs sunlight more readily than bright or reflective things,” Gomez said.

There are two types of aerosols: reflective and absorptive. Sulfate aerosols, which are byproducts of fossil fuel burning, are reflective and can cool the environment. These particles reflect the sun’s energy back into space, keeping it out of the atmosphere. 

Recent UCR research points to an unfortunate byproduct of improving air quality by reducing sulfate aerosols. Since these particles have a cooling effect, removing them makes climate change more severe and leads to an increase in wildfires, especially in northern hemisphere forests. 

Sulfate aerosols can also help make clouds brighter, more reflective, and more effective at cooling the planet. 

The researchers note that the only way to prevent additional wildfires when cleaning up reflective sulfate air pollution is to simultaneously reduce emissions of greenhouse gases like carbon dioxide and methane. 

Absorptive aerosols have the opposite effect. They trap light and heat in the atmosphere, which can raise temperatures. Black carbon, the most common aerosol emission from wildfires, is an absorbing aerosol. They not only directly make temperatures hotter, but indirectly as well by discouraging cloud formation and precipitation. 

“What I found is that the black carbon emitted from these California wildfires is not increasing the number of clouds,” Gomez said. “It’s hydrophobic.”  Fewer clouds mean less precipitation, which is problematic for drought-prone states.

While some studies have shown an association between fires and brighter, more numerous clouds, this one did not. 

Notably, the study found that days with fewer fire emissions had a more muted effect on the weather. “If the aerosols are coming out in smaller amounts and more slowly, the heating effect is not as pronounced,” Gomez said. 

Gomez is hopeful that mitigating CO2 emissions, alongside better land management practices, can help reduce the number of large wildfires. 

“There is a buildup of vegetation here in California. We need to allow more frequent small fires to reduce the amount of fuel available to burn,” Gomez said. “With more forest management and more prescribed burns, we could have fewer giant fires. That is in our control.”

(Cover image: ankarb/iStock/Getty)

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Southern California crews hampered by strong winds in first major wildfire of the year

Thousands told to be ready to evacuate in southern california's post fire.

Wildfires burn in Southern California

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Firefighters increased their containment of a large wildfire in mountains north of Los Angeles on Monday after a weekend of explosive, wind-driven growth.

The blaze, dubbed the Post fire, was eight per cent after scorching nearly 60 square kilometres and forcing the evacuation of at least 1,200 campers, off-roaders and hikers from the Hungry Valley recreation area.

"That eight per cent is good because it means we are increasing and bolstering our containment lines," said Kenichi Haskett, a Los Angeles County Fire Department section chief.

Firefighters hoped to hold the fire at its current size, but further growth was possible, Haskett said.

The Southern California fire erupted Saturday afternoon near I-5 in Gorman, about 100 kilometres northwest of Los Angeles. Two structures burned within the evacuated recreation area.

'Have your car fuelled up'

Flames were moving toward Pyramid Lake, a popular destination for boaters that was closed as a precaution on Father's Day. No houses were threatened Sunday, but officials warned residents of Castaic, home to about 19,000 people, that they should prepare to leave if the fire pushes further south.

"If you're in a warning area, be prepared with a 'go bag,' with overnight clothes and your cellphone, your medicines, your glasses. Have your car fuelled up," said Haskett. "Be ready to evacuate."

Low humidity and gusts around 80 km/h were expected throughout the day, and winds could pick up speed after sundown, warned the National Weather Service office for Los Angeles.

About 120 kilometres to the east, the nearly five-square-kilometre Hesperia fire forced road closures and prompted evacuation warnings after it broke out Saturday near mountain communities in San Bernardino County. The blaze was 30 per cent contained after no overnight growth.

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Meanwhile in Northern California, a small wildfire sparked Sunday prompted evacuation orders and warnings for a sparsely populated area near Lake Sonoma. The so-called Point fire sent up a huge plume of dark smoke as it churned through brush and timber about 130 kilometres north of San Francisco. It was 20 per cent surrounded after charring nearly five square kilometres of land.

Ben Nicholls, division chief of the Cal Fire district in the area covering the Point fire, said Monday morning that fire activity subsided overnight.

"Forecasted winds are supposed to be less than we experienced yesterday, which should allow the resources assigned for this operational period to build and strengthen the control lines that were put in place yesterday," Nicholls said in a video briefing.

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California firefighters gain ground against big wildfires after hot and windy weekend

Firefighters increased their containment of a large wildfire in mountains north of Los Angeles on Monday after a weekend of explosive, wind-driven growth along Interstate 5.

The Post Fire was 8% surrounded after scorching nearly 23 square miles and forcing the evacuation of at least 1,200 campers, off-roaders and hikers from the Hungry Valley recreation area on Saturday.

“That 8% is good because it means we are increasing and bolstering our containment lines,” said Kenichi Haskett, a Los Angeles County Fire Department section chief.

Firefighters hoped to hold the fire at its current size, but further growth was possible, Haskett said.

The fire broke out as  weather turned hot and windy  in a region where grasses spawned by a rainy winter have long since dried out and easily burn.

The  massive columns of smoke  that marked the fire’s initial rampage were gone by Monday morning. But Sunday’s smoke drifted some 225 miles northwest across the Mojave Desert to cast a slight haze in the Las Vegas area. Nevada air quality officials issued an alert advising children, older adults, and people with respiratory and heart disease to stay indoors.

In Northern California, a wildfire sparked Sunday prompted evacuation orders and warnings for a sparsely populated area near Lake Sonoma. Known as the Point Fire, it was 20% surrounded Monday after charring nearly 2 square miles about 80 miles north of San Francisco, and destroyed at least one structure.

Ben Nicholls, division chief of the Cal Fire district in area covering the Point fire, said Monday morning that fire activity subsided overnight.

“Forecasted winds are supposed to be less than we experienced yesterday, which should allow the resources assigned for this operational period to build and strengthen the control lines that were put in place yesterday,” Nicholls said in a video briefing.

The Southern California fire erupted Saturday afternoon near I-5 in Gorman, about 60 miles northwest of Los Angeles. Two structures burned within the evacuated recreation area.

To the south, popular Pyramid Lake was closed as a precaution on Father’s Day. Officials also warned residents of Castaic, home to about 19,000 people, that they should prepare to leave if the fire pushed farther south.

“If you’re in a warning area, be prepared with a ‘go bag,’ with overnight clothes and your cellphone, your medicines, your glasses. Have your car fueled up,” said Haskett. “Be ready to evacuate.”

About 75 miles to the east, the nearly 2-square-mile Hesperia Fire was 30% contained after no overnight growth. The fire erupted Saturday and forced road closures and evacuation warnings in San Bernardino County.

The Associated Press

Wildfire north of Los Angeles scorches 15k acres as dry, windy conditions persist

Thousands of people across California remained under evacuation advisories Monday as authorities battled wildfires that erupted over the weekend and torched thousands of acres while weather officials warned of more strong winds and dry conditions.

The so-called Post Fire broke out Saturday afternoon along Interstate 5 in Gorman, a community about 60 miles northwest of Los Angeles, according to the California Department of Forestry and Fire Protection . Fueled by powerful wind gusts, the blaze had burned 15,610 acres of dry, mountainous land by Monday afternoon. Eight percent of the fire has been contained, CalFire said.

More than 1,200 people fled from Hungry Valley Park, a popular destination for off-roaders and bikers known for its scenic motorcycle trails. To the south, authorities closed Pyramid Lake, a reservoir popular for weekend boating about 25 miles northwest of the city of Santa Clarita. A several-mile stretch south of Pyramid Lake was placed under an evacuation warning.

Firefighters battled the blaze as it approached Lake Pyramid overnight but were hampered by limited visibility as they tried to establish a perimeter on the fire's east side, CalFire said. One commercial structure has been destroyed by the flames. The cause of the fire was unknown.

The National Weather Service issued a red flag warning for the I-5 corridor in northwest Los Angeles County, warning of high temperatures, low humidity and wind gusts of 30 to 50 mph through Monday afternoon. Tuesday also could see strong northerly winds.

"These conditions will be favorable for the rapid growth and spread of wildfires, including the ongoing Post Fire complex," the weather service said.

Mika Olesen, 20, who lives in Castaic, a suburban outpost northwest of Santa Clarita, said smoke and embers have been blown into town since Saturday evening.

"It's hazy over the the mountains," said Olesen, who has never before had to evacuate because of a wildfire and hoped the blaze would be extinguished before it reaches more populated areas, like Castaic.

Blaze near Lake Sonoma prompts evacuation orders

In Northern California, firefighters battled another fire that has engulfed more than 1,100 acres across Sonoma County.

The fire began on Sunday just east of Lake Sonoma, about 25 miles northwest of Santa Rosa, at approximately 12:30 p.m. Within hours, authorities ordered hundreds of residents to leave their homes and businesses – including several wineries – between the lake and the small city of Healdsburg. Thousands of others were placed under evacuation warnings.

At least one firefighter has been injured in the blaze, which has been dubbed the Point Fire, according to CalFire. About 400 first responders have been sent to the scene, and authorities used helicopters, bulldozers, water tenders and 50 fire engines to battle the blaze.

Multiple structures were damaged and destroyed, officials said without providing exact figures. Through the night, firefighters used three helicopters in their latest attempt to quell the flames amid strong winds and low humidity, CalFire said. As of Monday afternoon, the blaze was 20% contained. The cause of the fire was under investigation.

Nearby areas, including North Bay and Contra Costa counties, issued Spare the Air advisories , warning that the air may be unhealthy for sensitive groups. Authorities temporarily banned wood burning and urged residents to avoid smoke exposure.

"Protect your health, stay indoors," the advisory says.

While Sonoma County is not under a red flag alert, a vast swath of the Sacramento Valley faces strong winds and dry conditions that will persist into Tuesday, the weather service said , urging residents to gather plans in case a fire breaks out in their area. The most active time for wildfires in California is generally between June and November.

"The threat of catastrophic wildfires isn't going to diminish until we actually start getting wetting rain and cooler conditions in the late fall, early winter," said Issac Sanchez, a spokesperson for CalFire.