Research forester Dr. Sarah McCaffrey explores some of the data, and counterarguments, surrounding that narrative. (Photo: Santa Rosa neighborhoods after the 2017 Tubbs Fire. Photo by David Loeffler, United States National Guard shared via Flickr Creative Commons.
How you tell a story influences what conclusions people draw from it (think Aesop’s Fables). Over the past decade, the overarching American wildfire narrative has become fairly focused on three dynamics: fuels buildup due to suppression, climate change, and the expanding wildland-urban interface (WUI). But what are these narratives based on?
There is a fair bit of research and debate as to when and where fuel overloading and climate change will have the most influence, in fact too much to be easily citable here. However, according to research for a paper that I’m developing with Matt Thompson of the Rocky Mountain Research Station and Courtney Schultz of Colorado State University, few data support the WUI story. Specifically, only limited data support the arguments for why and how the WUI is contributing to the wildfire problem.
For instance, a commonly cited concern is that 50–95 percent of wildfire suppression costs can be attributed to the protection of private property in the WUI. However, when our team followed the citations for this statement, we found that they all led back to data from a single 2006 Office of Inspector General (OIG) report (PDF, 1.57 MB). Further, the report reached that particular conclusion using data that most social scientists would find problematic at best. Stay tuned for my team’s paper to learn more about that report’s limitations.* We have found a few studies that examine the breakdown of suppression costs in a more rigorous manner, using meaningful metrics (e.g., the number of homes near the fire perimeter and the percent of private land). But, while they do find a positive association between homes being located in the WUI and suppression costs, none demonstrate causality or conclude that the costs of protecting private property come close to the low end of OIG’s estimates. Nor can we find any study that tracks changes in the WUI with changes in suppression costs over time, even though a key perceived “problem” with the WUI is that its expansion will automatically increase wildfire suppression costs.
Similarly, although it is often stated that wildfire-related housing loss is increasing, it is hard to find any data that support or deny this claim, as wildfire-related housing loss hasn’t been tracked consistently until fairly recently. Further, even the existing data are problematic. For instance, the National Interagency Coordination Center (NICC) claims that 2,638 homes were lost nationally in 2015 (see page 9 of this NICC report, PDF, 830 KB); while CAL FIRE reports that 3,217 homes were destroyed in California alone that same year. Further, while it is too short of a time span to draw any solid conclusions, it is worth noting that both datasets suggest that higher losses are periodic and due to specific wildfire events. For example, the graph below, which I developed using NICC annual summary reports, illustrates that when excluding the state that lost the most residences in a given year — say Tennessee in 2016, the year of the Gatlinburg fires — home loss (shown in green) is relatively flat.
Inaccurate Stories Are Unlikely to Lead to Effective Solutions
Accepting WUI narratives that lack sufficient supporting data can lead to developing solutions that are less likely to have the desired impact, because they may be targeting the wrong problem. Further, these proposed solutions may have unintended consequences because they don’t take existing data, or lack thereof, or the larger context into account. For instance, a common recommendation based on the WUI narrative is to limit development in fire-prone areas. However, while we do have fairly robust science concerning factors that make an individual home more fire resistant, we don’t have much information on what type of larger scale development is associated with improved wildfire outcomes. There are only a few relevant studies, and they offer conflicting “solutions.” For example, some studies suggest clustered housing would help with decreasing suppression costs, but others suggest clustered housing would lead to more losses.
Another common recommendation based on the WUI narrative is to form a national fire-insurance program similar to the National Flood Insurance Program, which appears to be seen as a means of ensuring that WUI residents bear the cost of living there. This recommendation ignores the significant evidence concluding that the National Flood Insurance Program has done little to shift the cost burden from federal taxpayers (and in fact has probably increased it) or to limit housing development in flood-prone areas. This argument also seems to assume that if individuals can’t obtain or afford insurance, then they will choose to not live in the WUI. However, there is no evidence that this is the case. It’s just as likely that individuals will continue to live there for a variety of reasons (e.g., amenities, affordability in other regards) and just take their chances, essentially making those with fewer resources even more vulnerable.
Further, insurance levers can raise an equity consideration: if insurance did have the desired effect, it is likely that only the wealthy would be able to live in the WUI since only they could afford to pay higher insurance premiums or to self-insure. It is worth asking whether that is an acceptable tradeoff.
Shifting Our Language
Through this process, I have begun to question whether the WUI is still a useful construct. While it may have been useful at one point to draw attention to the increasing intermingling of housing and natural vegetation, it now seems to create an artificial distinction that may be misleading. I doubt many of those who lost their homes in the recent California wildfires, particularly in Santa Rosa, thought of themselves as living in the WUI. Further, a preliminary analysis** by the University of Wisconsin shows that regarding the Tubbs Fire, many of the losses were not technically in the WUI. Instead, the largest portions of homes lost were in areas considered either too dense or not dense enough to be classified as the WUI. Forest Schafer’s recent blog post about how Lake Tahoe partners are rethinking their WUI is another example of the limitations of drawing artificial lines when assessing wildfire risk.
And then there is the question of how limiting development in the WUI would work. Beyond equity issues and the fact that we don’t have strong evidence regarding what “better” land-use planning for wildfire looks like, I always wonder, “So, where are people supposed to live then?” As one recent newspaper headline stated: “All Californians Live in Fire Country Now.” Perhaps just thinking about how we can best live in fire-prone landscapes may be a more useful way to frame the discussion, rather than creating artificial distinctions based on housing density and natural vegetation.
*This blog describes initial findings from a paper that Courtney, Matt and I are working on. The articles referenced in this blog post will be identified in that paper, which will be available on Treesearch once it is published.
**Author’s note, updated 2/2/2018: In clarifying the best contacts for the Tubbs Fire information described above, I also got an update on their findings. The proportion of the homes lost “outside of” the WUI (about 30 percent) is consistent with fires nationally, but distinct in that most of the losses from the Tubbs Fire were in areas of high density rather than very low density, which is more common nationally. More specifics and contacts are listed below as a comment from me, made on February 1.
Sarah McCaffrey, Ph.D., is a research forester for the USDA Forest Service, Rocky Mountain Research Station. Her research focuses on the social aspects of fire management. This work has included projects examining wildfire risk perception, social acceptability of prescribed fire and thinning, characteristics of effective communication programs, and incentives for the creation and maintenance of defensible space. She has also initiated work examining social issues that occur during and after wildfires, including evacuation-decision making, agency-community interactions during fires, public perception of wildfire management overall, views on the Cohesive Strategy, and perceptions about what it means to be a fire adapted community. She received her Ph.D. in Wildland Resource Science in 2002 from the University of California at Berkeley.
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