Thomas +50 Days

What were the ecological impacts of the Thomas Fire?

Monday, January 22 marks 50 days since the December 4, 2017 onset of the Thomas Fire.  The largest fire in modern (i.e. post-1931) California history was completely encircled with containment lines on January 12, 2018 (the 40th day of the burn).  CalFire reports 281,893 acres (440 mi2 or 1,140 km2) burned, 1,063 structures were destroyed and another 280 damaged, and two people burned to death.  The first rains in 10 months on January 9th initiated a new wave of problems across our fire-scarred region.  I was woken up in my Thousand Oaks home at 2:40 a.m. as the torrent really kicked in.  The hills above southern Santa Barbara County would soon catch a tremendous amount of rainfall very quickly with the worst of the rainfall occurring in a 15-minute span starting at 3:30 a.m. Montecito’s fire station received more than 0.5 inches (13 mm) within five minutes and Carpinteria an inch (25 mm) within 15 minutes.  That deluge in turn spurred some of the most destructive flooding and catastrophic mudflows, killing at least 20 (with three more victims still missing and likely dead).

32 of the 63 homes on Ventura’s Via Ondulando were obliterated in the first wave of destruction of the Thomas Fire. Image: Jay L. Clendenin / LA Times.

The focus up to now has understandably been on the immediate danger and impacts to people and property.  As the first responders attacked the flames, evacuated residents, and initiated clean-up, my colleagues, students, and I have been laying the groundwork for a better understanding of the ecological impacts of this massive conflagration.  While we won’t know the true magnitude of impact for some time to come, we have been fielding so many inquiries from the general public and media outlets that it seemed worthwhile to post a quick summary of our first impressions.  The summary below should therefore be read as a first pass.

Thomas Fire Initial Fire Progression (from Green to Red).

Understanding Thomas Fire Impacts

I kicked off the 2018 Ventura Land Trust’s 2018 Speaker Series last Thursday night in Ventura with a presentation on the impacts of the Thomas Fire.

I discussed the drivers of the fire and the environmental setting just prior to the December 4 onset before summarizing how the fire evolved and illustrating the initial impacts to plants and animals across Ventura and Santa Barbara Counties.  I particularly focused on impacts to vertebrates, drawing insight from a variety of sources including our data from the 2013 Camarillo Springs Fire that ravaged our CSU Channel Islands campus and the western Santa Monica Mountains.


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The fire was a fairly complete burn.  We estimate >90% of the vegetation within the fire perimeter burned, translating into a minimum of 3.6 million tons of CO2 emitted over the course of the fire.  This is equivalent to the emissions of all the shipping and boating activity in the State of California in 2015 or roughly 10% of the releases from the all agriculture across the state in 2015.

Recovery of our vegetation will be a very long road indeed thanks to the altered rainfall patterns and amounts global climate change has proffered up to our region (see below for a bit more on this).  While it is true that our southern California ecosystems have evolved with fire and many of our plants require fire to complete their life cycles, this bizarre new world in which we live will see plant communities recover very slowly relative to historic trends.

Thomas Fire burn scar is visible as the brown, denuded landscape in this December 18, 2017 image rendered from NASA’s OLI Landsat data.

Thomas Fire burning landscape. Image: Los Padres National Forest.

Oil Wells

By Christmas the incident command was reporting we had at least 30 oil seep fires across the back country between Ojai and Santa Paula with many more locations likely burning.  Exact numbers have been hard to come by as we have not yet been able to fly our own monitoring drones over the core of the burn region due to FAA restrictions (a so-called Temporary Flight Restriction for UAVs remains in place for foolish, bureaucratic reasons).  It is extremely likely that this estimate of 30 seep fires was overly conservative.  Putting out such oil seep fires is non-trivial due to the fact the burn quickly goes subsurface and cannot be extinguished by traditional water or suppression efforts.  Knocking it down requires specialized containment foam we don’t typically stockpile locally.

Most of our oil and gas wellheads and production facilities were relatively well (no pun intended) protected owing to standard, pre-fire vegetation management requirements.

OIl Seeps Burning on 150 Thomas Fire. Image: Ventura County Fire.


We are augmenting our 13-year, ongoing road kill-based censusing of wildlife across our region with a citizen-science effort to document fire-associated wildlife and more focused observations across the impacted region.  Much of this info is still coming in, but the patterns are clear: smaller-bodied animals have been the most heavily hit.  Rabbits, squirrels, and voles died in massive numbers.  Our larger-bodied animals (deer, coyote, etc.) generally escaped, save for their young.  We’ve documented few larger-bodied animal kills, only finding evidence for mortality of juvenile black bear (cubs), mountain lion (kittens), and coyote (pups).

In general, the natural history of the impacts to wildlife have unfolded as follows: small critters died in huge numbers, larger or flying animals were also killed but at a lower rate.

  1. Animals flee to riparian corridors/river bottoms or into the urban cores of downtown Ventura, Ojai, etc.  This also translates into higher road crossing rates, reflected in elevated road kill levels.
  2. In the wake of the immediate flames, animals hunker down in place and move very little initially.
  3. Scavengers (vultures, coyotes, crows) quickly begin to feast on the fire-killed carcasses of the victims and continue to do so for as long as two to three weeks post-burn.
  4. Surviving smaller-bodied herbivores begin to leave the protection of their initial refuge to forage, moving larger distances than typical.  This again is reflected in higher road kill levels.
  5. Predators quickly learn that remaining vegetation or other such surviving habitat patches harbor large numbers of prey and begin to stake out such sites to try and pick-off survivors.
  6. Larger-bodied herbivores and carnivores are pressed to move farther and farther with feeding forays much larger than their typical, pre-fire behavior.  We see elevated road crossings here, but a proportionally smaller increase than what we observe with our small critters.
  7. Populations of small animals continue to shrink over the coming months with many populations going locally extinct.  Populations of larger bodied animals are generally okay, but take time to recover given restricted prey bases and lowered recruitment of juvenile members.
  8. Over months to years we expect to see the vertebrate community to shift towards more opportunistic, generalist (e.g. American crows, coyotes, skunks) and away from more specialized (e.g. American badgers, long-tailed weasels, Pacific kangaroo rats) species with more narrow prey/feeding requirements.

This black bear (Ursus americanus) cub was enthanized due to the extensive injuries he received during the Thomas Fire. He was within the Los Padres National Forest.

This adult mountain lion (Puma concolor) is recovering from paw burns received in Santa Paula. Image: Donovan Varela.

This slightly burned and concussed adult barn owl (Tyto alba) has recovered well thanks to our friends at the Ojai Raptor Center. Image: Ojai Raptor Center.

This burned juvenile mountain lion (Puma concolor) was discovered on December 9, 2017 in the hills behind Ventura.

Thousand of cottontail rabbits (Sylvilagus sp.) were killed in the Thomas Fire, victims of both their inability to move large distances quickly and their susceptibility to heat. This individual was in the Ventura Botanical Garden above Ventura’s City Hall.

Wood rat (Neotoma sp.) killed by the Thomas Fire in the Ventura foothills.

Debris Impacts

Crowd sourcing impacts turns out to be quicker than waiting for the slow, prodding incident command updates.  Anyone can clearly see from the above screenshot (with the primary channels/immediate floodplains of Montecito highlighted blue) that impact from the flooding and debris flows were concentrated adjacent to our streams.

The 101 Freeway at the Olive Mill Road overpass is flooded with runoff water from Montecito Creek, on Tuesday, Jan. 9, 2018. Image: Mike Eliason / LATimes.

In the wake of any disaster, handling debris removal is a non-trivial matter fraught with problems and few easy answers.  Typically, we see waivers rapidly granted (usually kept on the down low and not widely advertised) to forestall existing environmental rules and procedures owing to the magnitude of the crisis and the time-critical situation unfolding on managers’ plates.  In the case of the post-Thomas Fire debris flows, Santa Barbara County secured emergency dumping/discharge permits from a host of agencies ranging from the Army Corps of Engineers to the California Coastal Commission that allows them to discharge up to 300,000 yards3 onto local beaches/coastal waters.  With those in hand, crews have been working non-stop to clear impacted landscapes and river channels/debris basins.  Large debris is going to the Ventura Fairgrounds for sorting with mud/slurry getting dumped directly onto sediment-starved Goleta Beach, on it-is-close-so-lets-use-it Carpinteria Beach, and across the Via Chaparral area (off of Cathedral Oaks).  Mud dumped onto these beaches is then bulldozed directly into the ocean.  This dumping has caused a major degradation of water quality (and possibly a large molluscan die off…but more on that in a future post) with closures of waters for swimming extending across a 48-mile swath of the Santa Barbara County shoreline.  Fecal coliform levels are 60 times higher than what we see in healthy nearshore waters from Gaviota Beach to the Santa Barbara-Ventura county line.  Downtown Santa Barbara-adjacent Leadbetter and Arroyo Burro beach waters have reported Enterococcus levels >24,192 MPN (Most Probable Number of bacteria per 100 ml sample; California state guidelines trigger concern at Enterococcus levels above 104 MPN).  Fecal indicator bacteria (FIB) levels at our East Beach monitoring site were also about >24,192 MPN (relative to the state standard of concern of 400 MPN).

Fire Weather

This disaster has all the fingerprints of climate change and is exactly the situation predicted by our climate change modeling over the past 20 years.  First and foremost we are seeing extreme variation in weather conditions.  From super wet to super dry.  The two-day storm that peaked on January 9, 2018 ended the 10-month dry spell for the Southern California Bight.  March 1 through December 31 of 2017 was the driest such period since we started keeping official precipitation records (in 1878), with only 0.69 inches (17.5 mm) of rain (explore this rainfall data yourself region-wide, or for Santa Barbara County, Ventura County, or Los Angeles County).  The cycling between dry spell and downpour makes plant and animals recovery difficult and distinct from historic trajectories often quoted in the media and agency information flyers.  The wind-fueled conflagration that was the Thomas Fire would not have been as big nor spread as quickly had we not experienced the nearly two week-long extended Santa Ana condition manifest in early to mid-December 2017.

In short, we have set the stage for destructive disasters such as this and simultaneously reduced our coastal ecosystem’s capacity to recover quickly from such assaults.  The Thomas Fire will likely add to our growing body of research confirming that climate change has contributed to California’s drier and hotter reality and our ever-longer fire season (we might even need to jettison the term “fire season”), aggregate number of large fire eventscost of  combatting such fires, and the spatial extent of individual wildfires.

California drought conditions on the week of January 10, 2017 (left) and November 10, 2017 (right). The warmer the color, the more intense the drought stress.


After some requests, I’m posting this interactive graphic of pre- and -post Montecito Flooding some have been asking about.

There have been many awesome satellite comparisons in the wake of the fire, but this below was one of the more popular ones that I’ve been seeing in media reports and using myself over the past week.  You can grab all the original imagery and see the full credits at this NASA site.

You are also welcome to post this code into your own post or website (if using WordPress, make sure to embed this via the “Text” tab and not via the “Visual” tab in your editor). The iframe code for the slider below is here:  <iframe frameborder=”0″ class=”juxtapose” width=”100%” height=”947.3537604456824″ src=”″></iframe>



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