Policy Brief PDF


Executive Summary
Just as Californians must live with earthquake risk, we must live with wildfires. These wildfires, shaped by ignitions, climate, and fuels, are likely to become more frequent and severe with climate change. The 2017 experience of the largest and most damaging wildfires in California history and ongoing destructive fires in 2018 provide a window of opportunity for learning to better coexist with wildfire. But both governments and people tend to adopt only short-term responses that don’t necessarily reduce risk effectively. Instead of focusing on traditional approaches like fighting fires and fuels management, we must make existing housing safer, develop future communities that avoid or accommodate our fire-prone landscapes, and emphasize evacuation planning and education.

Living with Wildfire
Wildfire has been an integral part of California ecosystems for centuries.1 But the area of the wildland-urban interface (WUI) where houses intermingle with wildlands increased by almost 20% between 1990 and 2010, with more than one million homes added in these fire-prone areas.2 Moreover, climate change will likely increase the frequency and severity of wildfire in many regions. As a result of this increased risk, we must consider creative policy solutions that move beyond fighting fires and managing fuels.

We must learn to live with wildfire, like we live with earthquakes. We readily understand that earthquakes are inevitable and we take actions as individuals and as a society to reduce their impacts. For example, we require earthquake-safe construction of homes and public buildings, we emphasize mapping of earthquake faults, and we practice “Duck, cover, and hold” in response to earthquakes. With fire, there remains instead a sense that fires are preventable or something that we can fight. We may be able to reduce the size or severity of many fires and sometimes protect infrastructure, but high intensity fires will continue to happen under the right conditions. And these conditions are more likely to occur in the next decade as temperatures rise.


Photo Credit: Ethan Turpin. http://www.ethanturpin.com

Fires in California
Analysis of historic fire regimes through tree rings and other methods shows that the forests, shrublands, and grasslands of California all experienced regular fire in the past. Nearly a third of homes in California are now in these WUI areas where fire is a natural phenomenon. Fires, like earthquakes, are going to happen; we just don’t know exactly when and where. Scientists do know that how large, severe, and frequent fires are in these landscapes depends on multiple factors, such as ignitions, climate, and fuel.

For many decades, ignitions – and reducing ignitions – were the focus of much public and government attention on reducing fire risks. Smokey Bear chided, “Only you can prevent forest fires”.Indeed, ignitions play a role in determining when fires occur.4 However, whether ignitions translate into fires that spread to larger areas with substantial losses of vegetation and risks to human infrastructure, depends strongly on the weather and fuel conditions at the time of ignition.

Large and more frequent fires can occur when high temperatures and lack of precipitation combine to create fuels that are dry and highly flammable.5,6 And they are exacerbated by winds. Santa Ana and sundowner wind conditions, which occur when warm, dry air from inland regions descends to the coast, are often associated with the largest most catastrophic fires, particularly in southern California.7 Northern California also experiences similar extreme winds, such as those that drove the devastating Tubbs Fire last year.8

Fires depend not only on how dry the fuels are but also on the amount and structure of fuels. For example, in a dense forest where understory plants connect fuels on the ground to the tops of trees, fires may be more intense. In contrast, open areas with less vegetation may impede the spread of fire. Regular low intensity fires in some forests can reduce fuels on the ground and consequently reduce the likelihood of high intensity fires. The last century’s focus on suppressing fires has contributed to more severe forest fires by allowing the buildup of fuels.9

Climate change will make fires worse
Temperatures throughout California are expected to rise in the next decades, leading to drier fuels, longer fire seasons, and more hot days with extreme fire risk. State-of-the-art climate projections, such as those used for the most recent Climate Impact Assessment,10 estimate that annual average daily temperatures are expected to increase by 3-5°C in the next few decades in Southern California. Increasing temperatures increase how fast fuels dry out. In mountainous parts of California, increasing temperatures also cause snow to melt earlier in the year, lengthening the summer fire season.11 The number of days with extreme temperatures, when fire risks are especially high, is also expected to double by 2050.

How precipitation in the form of rain or snow will change is less clear. Projections show relatively modest changes in average precipitation (including both increases and decreases depending on the region of California). Extreme rainfall events, which contribute to post-fire flooding, erosion, and even debris flows, are expected to increase in frequency and intensity.12 Taken together, these changes in climate are likely to increase the length of the fire season, fire size and fire severity, and the impacts of fire for much of the state.13,14

Right after fires is the time to make changes
The year 2017 had both the largest wildfire in recorded California history, the Thomas Fire, and the most damaging California fire, the Tubbs fire, which burned more than 5,000 structures. Moreover, five of the twenty most destructive fires occurred in 2017. In response, the California state legislature is considering at least 57 bills related to wildfire.15 Our research shows that this is typical; governments respond to wildfire quickly and decisively.16

But people and governments don’t always respond in ways that reduce the risk most effectively. Instead of long-term changes, they tend to take actions that reduce risks in the short term and they don’t allocate resources to places that need them most.17 For example, they place fuels management projects close to places that have had recent wildfires because public interest is high. These are often places at reduced risk of wildfire in the short term compared to places that haven’t just had a wildfire. And most responses to fire are focused on suppression and fuels management, rather than also emphasizing other policy responses. More than 94% of the FY2017 CAL FIRE budget was allocated to suppression.18

Suppression and fuels management alone can’t solve the wildfire problem
There is evidence that fuels treatments such as controlled burns, vegetation clearing, thinning, and fire breaks can sometimes reduce fire severity and limit the size of fires.19,20 It is important to recognize, however, that fuel treatments will not eliminate fires. If fuels are dry enough and temperatures and winds are high, fires will spread.21,22,23

Fuels treatments are like taking vitamin C and exercising to strengthen your immune system; these actions can reduce the effects of a virus and sometimes even prevent sickness, but they will not guarantee health. A virulent virus or just too much exposure means that you will still sometimes get sick, and sometimes very sick. And fuels treatments, like exercise, need to be maintained over time. Vegetation regrows following fuels treatments, so the effectiveness of treatments diminishes – often within five to ten years. Fuels treatments are also expensive, with estimated costs of more than $2,500 per acre in the 2007 Forest Management Plan for Tahoe National Forests. These costs can certainly be worthwhile for strategically placed fuels treatments because they can help to reduce risks. Ongoing advances in fire hazard mapping will help inform where and how often to perform fuels treatments on different landscapes. But fuels treatments will not eliminate fires, nor the potential for severe fires and the substantial losses associated with them.

Strategies for Living with Wildfire
Addressing the wildfire problem will require policy solutions that reflect a shift in perspective from fighting to coexisting with wildfire.24 Homes and people are the primary reason we care about burning landscapes. Protecting them requires strategic thinking about how to reduce the risks of loss to human life and infrastructure when fires occur. Reducing these losses will require reconsidering how and where we build and how we manage the WUI, including retrofitting structures to make them less flammable, encouraging fire-resistant development, and improving evacuations.

Reducing incentives to locate in the WUI: We need to motivate local decision makers to support safer and more sustainable development – recognizing that fire is inevitable in their community. The relative lack of disincentives to develop in risky areas that comes from state and federal payments for suppression and losses ensures that local decisions will continue to promote the disasters for which we all pay. And we need to make sure that people begin to pay the costs for living in fire-prone landscapes. Rather than encouraging development by guaranteed fire insurance25 and publicly funded fire suppression, we need to ensure that prospective homeowners can make informed decisions about the risks they face in the WUI.

Retrofitting existing housing stock: While local Fire Safe Councils and Community Wildfire Protection Plans (CWPPs) emphasize fuels reduction, this ignores the substantial potential to reduce vulnerabilities of homes to ignition during a wildfire. Homes often ignite and burn due to flying embers from a burning landscape relatively far from the structure itself. There is a crucial need for retrofits of existing structures, such as replacing wood roofing and screening attic vents, which are cost-effective ways to reduce home losses.

Creating more sustainable future development: Building new homes on fire-prone landscapes increases our exposure and the risk of losses. Expansion into the WUI also alters future fire probabilities themselves, and greatly limits use of fire as a land management tool. Because nearly all fire-related decisions hinge on where and how we build our communities, future development must be done in a more deliberate and sustainable way. California has begun to link fire-related building codes to the state’s Fire Hazard Severity Zone maps.26 This may not be enough. Future development also needs to be guided by what we have learned from other natural hazards, like earthquakes and landslides. A first principle is to concentrate structures in the lower hazard portions of the landscape and avoid the highest hazard areas. Further, when we do develop in the fire prone areas, we need to consider how neighborhood design will impact what happens when a fire does occur. We can achieve safer spatial layouts for neighborhoods (e.g., buffering with non-flammable features like orchards) and ease defense by fire fighters (e.g., clustering homes). Currently, land use planning does not recognize these concerns, and we all pay the price for it.

Improving evacuation planning, education, and warning systems: Regardless of where people end up living, we will eventually be faced with evacuation due to inevitable wildfires. Better evacuation planning is therefore needed, as is communicating these plans to the general public. Evacuation planning can begin with spatial land use planning that accounts for multiple exit routes and careful municipal plans. But it must extend to early education about evacuation. At present, most people simply assume that they will be informed when an evacuation is necessary, along with where exactly to go. Instead, they must know in advance how to respond to wildfire. Even when evacuation planning is extensive and the public is well educated about their options, there must be evacuation-warning systems that are robust (e.g., redundant technologies) and that the public understands (e.g., clear categories and consequences, and multimedia modes that are accessible to the diversity of cultural, educational and socio-economic backgrounds that make up local communities). Education and warning must also address the many consequences of fire beyond home and infrastructure loss, including health impacts of exposure to smoke, and post-fire flooding and landslide risk.

We have a great deal to learn from other inevitable natural hazards. From seismic planning to earthquake retrofitting to education campaigns, following the roadmap we use for earthquakes can move our response to wildfire from reactive fighting to comprehensive preparedness. With policy changes to facilitate less risky decisions about where and how we build our communities, we can better coexist with wildfire. We need to shift our perspective so that local governments and individuals share responsibility in meaningful and constructive ways. Increasing wildfires – in number, size, and severity – may be inevitable. However, increasing home losses, fatalities, and costs are not.

We thank Janet Choate for her assistance. This work was supported by Southern California Edison, NSF Hazards SEES (EAR-1520847), the National Socio-Environmental Synthesis Center, and the Strategic Environmental Research Initiative at the Bren School, University of California, Santa Barbara. For more information about our research, visit: https://serifire.com.


  1. van Wagtendonk, J.W., Sugihara, N.G. , Stephens, S.L., Thode, A.E., Shaffer, K.E., & Fites-Kaufmann, J.A. (2018) Fire in California’s Ecosystems. Second edition. Berkeley: Univ of California Press
  2. https://www.nrs.fs.fed.us/data/wui/state_summary/#wui-areaUnited States Department of Agriculture. Available at
  3. Smokey Bear. Available at https://www.smokeybear.com/en
  4. Syphard, A.D., Radeloff, V.C., Keeley, J.E., Hawbaker, T.J., Clayton, M.K., Stewart, S.I. & Hammer, R.B. (2007) Human influence on California fire regimes, Ecological Applications 17, 1388-1402. doi:10.1890/06-1128.1
  5. Krawchuk, M., & Moritz, M.A. (2011) Constraints on global fire activity vary across a resource gradient, Ecology 92, 121–132. pmid:21560682 ;
  6. Abatzoglou, J.T., & Kolden, C.A. (2013) Relationships between climate and macroscale area burned in the western United States, Int J Wildl Fire 22(7), 1003–1020. doi:10.1071/WF13019
  7. Moritz, M.A., Moody, T.J., Krawchuk, M.A., Hughes, M., & Hall, A. (2010) Spatial variation in extreme winds predicts large wildfire locations in chaparral ecosystems, Geophysical Research Letters 37(4), L04801. doi:10.1029/2009GL041735
  8. Moritz, Max. (2017) California needs to rethink urban fire risk after wine country tragedy, The Conversation. Available at https://theconversation.com/california-needs-to-rethink-urban-fire-risk-after-wine-country-tragedy-85966
  9. Steel, Z.L., Safford, H.D., & Viers, J.H. (2015) The fire frequency-severity relationship and the legacy of fire suppression in California forests, Ecosphere 6(1), 8. doi:10.1890/ES14-00224.1
  10. Livneh, et al., (2015) Climate change research plan for California, http://climatechange.ca.gov/climate_action_team/reports/climate_assessments.html
  11. Westerling, A.L., Hidalgo, H.G., Cayan, D.R., & Swetnam, T.W. (2006) Warming and Earlier Spring Increase Western U.S. Forest Wildfire Activity, Science, 313(5789), 940–943. doi:10.1126/science.1128834
  12. Swain, D.L., Langenbrunner, B., Neelin, J.D., & Hall, A. (2018) Increasing precipitation volatility in twenty-first century California, Nature Climate Change 8, 427–433.
  13. Dennison, P. E., Brewer, S.C. , Arnold, J.D., & Moritz, M.A. (2014) Large wildfire trends in the western United States, 1984–2011, Geophys. Res. Lett. 41, 2928–2933. doi:10.1002/2014GL059576 ;
  14. Ayres, A., Degolia, A., Fienup, M., Kim, Y., Sainz, J., Urbisci, L., Viana, D., Wesolowski, G., Plantinga, A.J., & Tague, C. (2016) Social Science/Natural Science Perspectives on Wildfire and Climate Change, Geography Compass 10, 67–86. doi: 10.1111/gec3.12259
  15. California Legistative Information. Available at  https://leginfo.legislature.ca.gov/faces/billSearchClient.xhtml?author=All&lawCode=All&session_year=20172018&keyword=wildfire&house=Both
  16. Wibbenmeyer, Matthew and Anderson, Sarah and Plantinga, Andrew, Salience and the Government Provision of Public Goods (May 4, 2018). Available at SSRN: https://ssrn.com/abstract=3173855or http://dx.doi.org/10.2139/ssrn.3173855
  17. Anderson, S.E., Bart, R.R., Kenned, M.C., MacDonald, A.J., Moritz, M.A., Plantinga, A.J., Tague, C.L., & Wibbenmeyer, M. (2018) The dangers of disaster-driven responses to climate change, Nature Climate Change 8, 651-653. Available at https://www.nature.com/articles/s41558-018-0208-8
  18. California 2017-2018 State Budget. Available at http://www.ebudget.ca.gov/budget/publication/ – /e/2017-18/Department/3540
  19. Stephens, S.L., McIver, J.D., Boerner, R.E.J., Fettig, C.J. , Fontaine, J.B., Hartsough, B.R., Kennedy, P.L., & Schwilk, D.W. (2012) The effects of forest fuel reduction treatments in the United States, BioScience 62(6), 549-560. ;
  20. Agee, J.K., & Skinner ,C.N. (2005) Basic principles of forest fuel reduction treatments, Forest Ecology and Management 211, 83–96.
  21. Pyne, S.J., Andrews, P.L., & Laven, R.D. (1996) Introduction to wildland fire. 2nd edition. New York, NY: John Wiley and Sons, Inc. 769 p.;
  22. Moritz, M.A., Keeley, J.E., Johnson, E.A., & Schaffner, A.A. (2004) Testing a basic assumption of shrubland fire management: how important is fuel age?, Frontiers in Ecology and the Environment 2(2), 67-72.;
  23. Syphard, A.D. , Keeley, J.E , & Brennan, T.J. (2011) Comparing the role of fuel breaks across southern California national forests, Forest Ecology and Management 261(11), 2038-2048. doi:10.1016/j.foreco.2011.02.030.
  24. Moritz, M.A. & Knowles, S.G. (2016) Coexisting with Wildfire, American Scientist 104(4), 220. doi: 10.1511/2016.121.220
  25. California Fair Plan Property Insurance. Available at https://www.cfpnet.com/
  26. Cal Fire. Available at http://www.fire.ca.gov/fire_prevention/fire_prevention_wildland_zones

Recommended Reading

Fire Regimes – and what influences them
Hessburg, P.F., Salter, R.B., & James, K.M. (2007) Re-examining fire severity relations in pre-management era mixed conifer forests: inferences from landscape patterns of forest structure, Landscape Ecol 22, 5-24.

Moritz, M.A., Batllori, E., Bradstock, R.A., Gill, A.M., Handmer, J., Hessburg, P.F., Leonard, J., McCaffrey, S., Odion, D.C., Schoennagel, T., & others (2014) Learning to coexist with wildfire, Nature 515, 58–66.

Pyne, S.J. (1982) Fire in America. A cultural history of wildland and rural fire. Princeton, NJ: Princeton University Press. 654 p.

Climate Projections
Pierce, D.W., Cayan, D.R., & Thrasher, B.L. (2014) Statistical downscaling using Localized

Constructed Analogs (LOCA), J of Hydrometeorology 15, 2558-2585.

Climate Change Impacts on Fire
Abatzoglou, J.T., & Williams, A.P. (2016) Impact of anthropogenic climate change on wildfire across western US forests, Proceedings of the National Academy of Sciences 113(42), 11770-11775.

Mann, M.L., Batllori, E., Moritz, M.A., Waller, E.K., Berck, P., Flint, A,L. , Flint, L.E., & Dolfi, E. (2016) Incorporating anthropogenic influences into fire probability models: effects of human activity and climate change on fire activity in California, PLoS One 11(4), e0153589.

Potter, C. (2014) Understanding Climate Change on the California Coast: Accounting for Extreme Daily Events among Long-Term Trends, Climate 2(1), 18-27; doi:10.3390/cli2010018

Effectiveness of fuel treatments
North, M., Brough, A, Long, J., Collins, B., Bowden, P., Yasuda, D., Miller, J., & Sugihara, N. (2015) Constraints on Mechanized Treatment Significantly Limit Mechanical Fuels Reduction Extent in the Sierra Nevada, Journal of Forestry 113(1), 40-48.