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Changing Fire Régimes in California, Changing Geographies of Hazard. What Now?Paul S. Laris and Christine M. Rodrigue
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First, I (Paul Laris) will give a quick review of fire policy in the US and then we will focus in on California with special attention to Southern California [ Slide 1:4 ].
Quick, say the first thing that comes to mind [ Slide 1:5 ]!
Even my undergrad students today think of Bambi when they see this image. The point is that our thinking about fire is deeply tied with ideas about fire being a bad thing and something we need to fear and control [ Slide 1:6 ].
This is actually a famous image by McColgan that went viral in 2000 [ Slide 1:7 ].
He was so unhappy with how his image was used—to incite fear about fire-- that he published a rephoto, to show how nature had recovered a couple of years later—these fires are actually good for the deer population [ Slide 1:8 ].
Bambi and Smokey the Bear teamed up in one of the most successful ad campaigns in history—suppress fire [ Slide 1:9 ].
It took the equipment and personnel from WWII to suppress fire—for about 50 years [ Slide 1:10 ].
As Stephen Pyne explains The policy story actually begins in 1910 with some terrible fires in the mountainous West [ Slide 1:11 ].
What is interesting from our perspective, is that there was quite a debate about fire policy at the time. This article from Sunset Magazine in the same year argues against the federal policy and makes the case that fire should be used as a tool by people to manage our forests [ Slide 1:12 ].
Fire prevention policy worked for a relatively short time and then fires exploded across the landscape primarily as a result of fuel build up, ladder effects, etc. Suppression was not the answer to the fire problem in the American West and this touched off a huge effort to develop preventative burning strategies… [ Slide 1:13 ].
Harold Biswell from Berkeley was a key figure. He worked to show how fire could be reintroduced to reduce hazard in some forests [ Slide 1:14 ].
Unfortunately, even Biswell and Berkeley could not stop the fire crisis… [ Slide 1:15 ].
The number of acres burned in California steadily increased -- it is now well over 1 million acres per year [ Slide 1:16 ].
In addition to fuel build up, climate change plays a role: Increased drought leads to tree deaths and early snow melts increase the length of the fire season in mountainous areas… [ Slide 1:17 ].
What is going on? Is it climate change? Fire policy? Number of ignitions? By some counts there are fewer fires, but they are bigger [ Slide 1:18 ].
If we take Stephen’s Pyne’s broad brush stroke, there are two Californias with too much fire in the SW and too little in the NE [ Slide 1:19 ].
Indeed, too much fire causes “type conversion” of chaparral into annual grasses, the latter are more flammable and perpetuate frequent fire according to one line of thinking.
Note this image is from the Santa Monica Mountains. Three fires in 11 years resulted in a type conversion. Grasses are more flammable and thus this is a positive feedback [ Slide 1:20 ].
Here are results from a very recent study for the entirety of So Cal ranges—areas of bright orange have a history of frequent fire and are thus threatened by type conversion [ Slide 1:21 ].
Finally, no discussion of fire in California is complete without a mention of the great debate [ Slide 1:22 ].
By régime we generally mean the frequency, intensity and type of fire, but a good rule of thumb is that the longer the return interval, the more intense the fires
[ Slide 2:1 ].
Wildfire régimes reflect the interaction of all kinds of physical factors, including the kinds of vegetation in an area, regional climates, terrain ... and human factors, such as ignitions and the policies and practices of landscape management [ Slide 2:2 ].
Going back to Pyne, we have very different biogeography around the State.
There's a N/S divide and an E/W divide.
We have conifer forests to the north and east, oak woodlands to the west and center, deserts to the southeast ... and Mediterranean scrub along the southwest coast [ Slide 2:3 ].
This creates what we call “pyro-geography.”
Here are just a few examples. The sequoia and the Douglas fire have adapted to different regimes.
Remember, Jon Keeley tells us that plants adapt to fire régimes, not to fire itself -- REPEAT [ Slide 2:4 ].
One of the most important physical factors is wind We know very well that that our worst fires occur during Santa Ana and sun-downer winds (and Diablo winds up north).
Any ignition event in this kind of strong, drying wind is almost guaranteed to create a landscape-clearing conflagration.
On a sunnier note, recent research modelling future climates in California suggests that the Great Basin High is going to weaken over the next few decades: less wind [ Slide 2:5 ]!
And now we come to the ignition end of the wildfire régime [ Slide 2:6 ].
Notice how the predominant source of ignitions varies from S to N and from E to W [ Slide 2:7 ].
Fire follows people in So Cal. We do not have a problem with too little fire, we have too much [ Slide 2:8 ]!!!
This image was before the most recent Malibu fires, but it clearly shows how some areas have far too much fire [ Slide 2:9 ].
And here are the new Woolsey and Hill fire perimeters [ Slide 2:10 ].
Most places in the Los Angeles and Ventura counties WUI have burned 1-4 times over the last 85 years, but there are distinct fire corridors where fire has gone through from 5-11 times, just in the last 85 years [ Slide 2:11 ].
(Chrys Rodrigue) Fire follows people, and people are moving into wild vegetation by the droves. Their settlements produce something we call the “Wildfire-Urban Interface,” or WUI [ Slide 3:1 ].
This map shows areas by the dominant time they experienced urban settlement.
Older urban areas developed mainly in the 1930s-1960s (yellows and oranges); new developments are shown in red.
Red dominates the peripheries of urban areas – and pop up as newer, smaller settlements in the mountains.
This is the “Racial Dot Map” by the University of Virginia. Each dot is a person [ Slide 3:2 ].
Blue dots are non-Hispanic white people (green is black; red is Asian; gold is Latinx).
Note how the newer urban settlement is dominated by blue dots here.
WUI settlement is biased demographically.
The local area shows this same pattern, white folks in the WUI [ Slide 3:3 ].
Statewide, we see that the WUI around urban areas is dominated by richer people [ Slide 3:4 ].
In Northern California, the wealth signal is weaker in the Sierra foothills.
Here, well-to-do urban immigrants are moving into and displacing the “Old West” occupants of mining, forestry, and tourist towns, so their wealth is diluted by the presence of the rural people they're starting to crowd out.
Here in Southern California, we see that the WUI is dominated by the better-off [ Slide 3:5 ].
People moving into the WUI are not representative of the population of California (richer, whiter) [ Slide 3:6 ].
They are taking on an awful risk and may not know what they're getting into, though some are pretty nonchalant. Many are, like most of us, swamped by life and that gets in the way of prioritizing dealing with our risks.
Risk is not the same thing as vulnerability [ Slide 3:7 ].
Risk is the probability that you, your loved ones, or your possessions will be exposed to the forces unleashed by a disaster, basically the probability of mortality, morbidity, or loss. Anyone in the WUI is at risk.
Vulnerability is something else entirely. It refers to your ability to learn about an impending event, evade it, and recover from any impacts it had on you.
If you are poor or otherwise marginalized, you may be at high risk to a hazard AND unable to get the resources you need to recover from it [ Slide 3:8 ].
If you are rich and privileged, you are better able to recover, because you may have personal resources to recoup, you may have adequate insurance and can rebuild, and you may be able to command social resources by knowing your way around a bureaucracy.
In most hazards in most parts of the world, the poor and marginalized who are forced to live in hazardous locations, raising both risk and vulnerability when disaster hits [ Slide 3:9 ].
Rich people can live in safer locations, reducing their risk and reïnforcing their relative invulnerability
With WUI hazard in California, however, we have an unusual situation: It is the rich who are moving into hazardous locations, putting themselves at great risk!
They outsource their vulnerability (firefighting costs and insurance mechanisms), and it takes a large social subsidy to facilitate life in the WUI.
Federal costs are climbing, even when you correct for inflation [ Slide 3:10 ].
Note how CAL FIRE budget allocations rise over the last dozen years in the graph to the right (grey bars).
Every year, though, the budget is blown through and extra allocations have to be provided (red bars)
Nearly half of all Federal firefighting costs are spent in California [ Slide 3:11 ].
Only about a quarter of burned acreage is in California
This is because more of California fires are WUI fires, densely settled and difficult terrain.
This contrast suggests the disproportionate subsidy involved in letting people live in the WUI.
Another major subsidy facilitating development of the WUI is insurance [ Slide 3:12 ].
Insurers, sensibly enough, deny coverage to WUI homes
The FAIR Plan is a State-sponsored assigned risk pool.
Insurers must accept random assignment of homes proportionate to their total market in California
The real kicker is that premia have to be “affordable.”
So, insurers can't cover their asset exposure from WUI
They have to get the missing funds from other homeowners.
This is a well-hidden upward income transfer/subsidy facilitating occupation of the WUI.
Further development should be stopped by zoning, but that's not going to happen: Developer lobbies and speculators are powerful and vested in continuing growth in the WUI [ Slide 4:1 ].
California's population continues to grow, leading to development pressures everywhere.
Firewise regulation of rebuilding is marginally more possible than zoning the WUI off-limits, but it, too, faces powerful resistance from homeowners and from developers.
Look at the decades-long struggle to outlaw shake rooves!
Ironically, there's quite a bit that WUI homeowners (and landlords) can do to make it safer to live there [ Slide 4:2 ].
You can't firePROOF your home, but you can drastically raise the probability that it can withstand the firewall coming through!
Recommendations are available, grounded in decades of fire behavior modeling.
There are things individuals can do but, while people living up there need to take individual responsibility, this is not strictly a job for the rugged individualist: It takes a village to fire-harden a community.
It's kind of like vaccination: You can rely on herd-immunity and shirk your own vaccination – or you can lean in and help everyone avoid unnecessary disease.
How does fire spread [ Slide 4:3 ]? There are two basic mechanisms behind the spread of a fire.
First, the radiant heat of the firewall raises the temperature of your house's sides or porches to their ignition points. This can cause the home to start burning on its own IF the firewall can get close enough for long enough.
The heat from the firewall declines with distance from the firewall, basically, the inverse-square law.
The cooler the temperature, the longer it will take for a given heat flux to ignite your home's walls.
Fire walls generally move on pretty quickly, so it's a matter of keeping the walls cool enough to need more time than the fire has to ignite your home.
Second, embers or firebrands are lofted by the convection above the fire or by the winds driving the fire [ Slide 4:4 ].
They can travel for miles and land on susceptible material, and then conduction brings a small part of that material to its ignition temperature.
Here is a map of burned and unburned homes in Scripps Ranch during the Cedar Fire of 2003. The red arrow shows the fire's approach; the red parcels burned. The three lots to the south were not near the firewall.
Embers hit home 1 and it started burning and then that caused home 2 to go up, too.
How can a WUI resident block fire spread? First, deal with the radiant heat from the fire wall. This house has flammable native shrub vegetation close enough to ignite the home through radiation [ Slide 4:5 ].
Here is a post-mitigation diagram [ Slide 4:6 ].
Zone 1 is the well-manicured and well-watered zone, with hardscape near the house to reduce contact between litter and the house itself. Aim for ~50 feet. There should be no trees close to the house and any trees within 50 feet should have all lower branches removed up to ~10 feet to reduce the danger of laddering (when a surface fire climbs up and creates a hot crown fire).
Zone 2 includes native vegetation, but with progressively more aggressive clearing of all dead matter and thinning and pruning of living plants on the Zone 1 side (maybe 50%) and less aggressive on the other side (maybe 30%). This would go out to meet the unmodified wild vegetation around 100 feet from the house.
These distances would be in keeping with fire science research on heat flux and ignition temperatures.
It is not necessary to denude the landscape 100 feet out like this well-intentioned soul did [ Slide 4:7 ].
Clearing all the native vegetation like this will create nothing but exotic annual grassland.
This is terrible as animal habitat, and it also creates a flashy fine fuel that will eventually endanger this house with the fast fires such fuels produce.
Second, deal with the blizzard of firebrands [ Slide 4:8 ]!
Hunt for and eliminate ALL dead litter or needles from your roof, rain gutters (what ARE those good for, anyway?), porches, decks, and steps.
Put fine mesh (like mosquito screen) on the inside of all gable and soffit vents – embers commonly enter the attic through the vents.
Fire-resistant outdoor furniture only and remove brooms and hemp/sisal “welcome” mats.
The idea is to remove small, fine things in contact with your house, so they can't carry fire to your house
Be especially vigilant if you have a complex roof, with lots of nooks and crannies to trap litter and snag firebrands [ Slide 4:9 ].
Do you really need rain gutters? Those things get a lot of houses burned down. If you are really attached to them for whatever reason, keep them CLEAN constantly (and, while you're up there, case the flashing and roof irregularities for litter and sweep it off).
Keep litter swept away from the foundation of the house, and that's not a good place to use mulch.
With WUI fires, it is less about the vegetation than it is about the ignitability of the house and of all outbuildings [ Slide 4:10 ].
Hold the vegetation back, but really focus on the little things that trap embers, because most homes burn from flying embers rather than the heat of the firewall.
It is possible to keep the house from igniting, even if all the vegetation surrounding it goes up [ Slide 4:11 ].
A few structural fine points [ Slide 4:12 ].:
- Fireproof all outbuildings!
- NO SHAKE ROOVES!!!
- Beware of eaves (and/or mesh up all vents up there)!
- Keep vegetation and litter off your roof and your rain gutters (get rid of the rain gutters?)!
This is Paradise.
Every home in this cul-de-sac is gone, other than what looks like a chicken-coop in the lower right.
Virtually every tree is just fine, nice and green. This was not a crown fire: It was a surface fire. It never laddered up into the canopy!
Instead of jumping from grass or shrubs or trees to houses, it jumped from one house to the next.
Fire mitigation in the WUI has to be a community endeavor, not just an individual household's responsibility [ Slide 4:14 ].
Project Firewise is a community-based project to assess the specific fire hazard in a specific location and engage community leaders, homeowners, planners, firefighting professionals, and even developers to coming up with locally-tailored assessments and mitigation and preparation projects.
Communities can try for recognized Firewise Community status and qualify for funding to make the process of community-based fire hazard mitigation easier.
You can get to their web site at http://www.firewise.org.
Takeaways [ Slide 4:15 ]: Why the increase in major firestorms?
- Fire régimes reacting to climate change and to changes in vegetation?
- Suburbanization of the WUI?
- We will have longer fire seasons, more droughts, and more intense rains that stimulate growth of vegetation.
- Vegetation is changing as fire régimes change and as people bring in and facilitate exotic species that themselves affect fire régimes.
- We may, however, experience less wind, which is a massive driver of major firestorms
That said, understanding the balance between vegetation and structure ignitability opens a path, where WUI residents can take greater personal responsibility to modify their homes' ignitibility and rely less on unfair social subsidies [ Slide 4:16 ].
While individual action is necessary to reduce loss of life and loss of homes in the WUI, it is not sufficient. We need a community-based approach, such as that supported by Project Firewise.
It is possible to develop a more sustainable resilience to wildfire hazards. This will let us cope better with today's fires and help us better face the changes in wildfire coming at us with climate change.
Document maintained by Dr.
Rodrigue
First placed on web: 03/15/19
Last revision: 03/15/19