Les Joslin’s story last Saturday about Smokey Bear signage reminded me of Nagy et al. ‘s paper, which I wrote about on TSW here on Monday. There must be something in the atmosphere, because today Nick Smith had a link to an article on this Higuera et al. paper in his newsletter today.
Here’s the story in the Bozeman Chronicle. A few interesting points..
A new study shows that structure loss from wildfires rose nearly 250% across the Western United States over the last decade and 76% of wildfires that burned homes and other structures were human caused.
Just under 80% of the structures that burned in wildfires between 2010 and 2020 were located in California. While that state dominated the trend, the number of structures lost to wildfires increased overall in every Western state, apart from New Mexico.
When it comes to policy solutions, Higuera sees several. First, people can re-emphasize the “Smokey the Bear” message, particularly later in the fire season. Second, they can consider large-scale changes in how, where and whether they build. (my bold)
While solutions may differ from region to region, they could involve rethinking “how power gets transmitted across the landscape” and the affordable housing crisis, which is part of what’s leading to development in flammable vegetation, according to Higuera.
Here are the conclusions from the paper (open access, hurray!). I tried to remove all the page numbers but may not have been entirely successful.
Our study reveals key drivers of the wildfire crisis in the West, and therefore when, where, and which “levers” can be pulled to reduce the chances of future fire disasters. We focused on structure loss as an acute negative impact of wildfires, highlighting a significant increase in structures destroyed by wildfires, by over 3x between 1999-2009 and 2010-2020 (Fig. 2B). Critically, we also show that wildfires have become more destructive, with the number of 19 structures destroyed per 1000 ha burned increasing, by 160% between the last two decades (Fig. 20 2C). This West-wide pattern was dominated by California and from events in just three recent years (2017, 2018, 2020), but nearly every Western state exhibited higher structure loss rates over the second decade of the 21st century (Fig. 4I, S4).
Increased loss rates indicate that wildfire-related structure loss did not increase simply due to more area burning. Likewise, although our analysis did not resolve structure exposure to individual wildfires, we estimate that the proportion of structures destroyed by wildfire outpaced higher structure abundance in flammable vegetation alone (Table S1). The causes of increased structure loss thus reflect complex human-environment interactions, not “either” more area burning “or” increased development, but both, and more. When and where human-related ignitions occur, how many structures are built among flammable vegetation, and how climate 30 and land use affect fuel abundance and fuel aridity over timescales of days to decades are all interacting to drive trends in structure loss.
Recognizing the complex drivers of fire disasters has important implications for mitigation and adaptation. For example, efforts to reduce structure loss must look beyond simply limiting area burned generically. In fact, across the West 88% of wildfires, accounting for 45% of the total area burned, had no associated structure loss (Fig. 1A). While not explicitly assessed here, much of this burning is not a crisis per se and can provide resource benefits (41–44). The wildfire crisis generally and structure loss specifically are largely driven by extreme events, highlighted clearly in recent years (Fig. 1B). The overwhelming majority of wildfires that result in structure loss are started by human-related ignitions, and they are occurring in regions with increasingly high structure density within flammable vegetation (21; Fig. 4J). Consequently, the number of structures destroyed by wildfire in the West in any single year was well explained by the total area burned from human-related ignitions; and, total structure loss in a state over the past two decades was well explained by the number of structures in flammable vegetation (Fig. 5). Both elements have increased between the past two decades – area burned from human-related ignitions by 51%, and structure density by 39% (Fig. 4) – and are leading contributors to increased structure loss rates.
While numerous studies highlight increased fuel aridity from anthropogenic climate change as a key enabler of rising wildfire activity in the West (6, 14–17), in parallel to these changes we have shown that human factors operating over shorter time scales are increasingly contributing to wildfire disasters. The consequences of human-related ignitions, specifically when and where fuel aridity is high and lightning ignitions are rare, are becoming magnified in the context of climate change. Therefore, efforts to reduce human-related ignitions will be increasingly important beyond historical lightning-caused fire seasons, for example in spring, fall, and even winter months (Fig. 3F, S5).
(my bold, and I would add based on experience in my part of the country “the ability of fire departments to jump on them quickly when they do occur.”)
The patterns highlighted here varied widely across the West, emphasizing the importance of understanding spatial and temporal characteristics of wildfires – fire regimes – as integrated social-ecological phenomena (29, 30, 45). Mitigating anthropogenic climate change, given its impacts on fuel aridity (14, 6, 19), is a clear overarching necessity for addressing the wildfire crisis. At smaller scales of individual states, policymakers and managers may benefit from emphasizing other aspects driving increased structure loss, including structure expansion into flammable vegetation, increased ignition from human-related sources, or in states with below- average structure loss, reducing the chances of lighting-ignited fires spreading into developed areas (32, 43). Mitigation and adaptation approaches in predominantly rural states, like Wyoming, Montana, and Idaho, may look different than in more densely populated states, like California, Colorado, and Washington. Additionally, states with low structure loss rates may look to those with high structures loss as harbingers of future change, and ideally glean ways to avoid similar outcomes as structure expansion and densification trends continue. Two clear implications emerge from this and other recent work (20, 21, 32, 33) to help prevent wildfires from becoming disasters: reduce unintentional human-related ignitions, particularly near homes and during periods of extreme fire danger; and carefully consider if and how structures are built, including building with fire-resistant materials, minimizing flammable vegetation near structures, and providing mechanisms to do so equitably across socioeconomic conditions.
I think most of us would agree , as the authors say, that the entire wildfire problem or issue is partially social (as is pretty much everything) in nature. So my questions are:
1. Where is the social science around these human factors and what interventions work to change them?
Unplanned ignitions from human sources – ereafter “human-related ignitions” – include backyard burning, downed power lines, escaped campfires, etc., and are a well-recognized component of contemporary fire activity across the
United States (22, 23)
After all, there is a great deal of good literature on attitudes toward prescribed burning and fuel treatments. But maybe I’m not aware of the literature on strategies to reduce human-caused ignitions.
2. If there is none, why not?
Is it because it’s unstudiable for various reasons (under the litigation cone of silence?), or because there aren’t enough social scientists around, or because it’s not popular with granting agencies, or ???