This letter is being presented by EMBER opponents as a scientific justification for their opinions. It was sent on April 26, 2025 by four private individuals, or which two are university professors, Longcore and Ossola, to the Zone Zero Regulatory Advisory Committee of the California Board of Forestry and Fire Protection, as comments for future regulation.
Unfortunately, it suffers from significant deficiencies that do not allow it to represent a justification of attacks on EMBER. Here is why:
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This is not a peer-reviewed article but an opinion letter.
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The authors are not wildfire scientists. but, instead Environmental and Plant scientists. So assuming their feedback is good from the point of view of their field, what do they rely on for wildfire science?
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The keystone of their wildfire science bibliography is the article by Alexandra Syphard that appears, at first sight, to deny advantage of defensible space (something that has been proven many times over in the past 30 years of wildfire science). Unfortunately, Alexandra Syphard disagreed with this interpretation of her article, and is in strong support of EMBER, as per her letter, already quoted by councilmember Brent Blackaby in another email, that says, among other things: "I am sorry to learn that my work is being somewhat misrepresented in a way that could make residents more at risk to wildfire. […] My study found significant benefits of defensible space, particularly the closer you are to the structure. It is my thought that the Zone Zero requirements are one of the most important things residents can do to protect their property from wildfire."
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So, what is the meaning of her article? She (the author herself) says that “The study in which I recommend that excessive defensible space may not be needed is specifically talking about those who want to far exceed the 100’ minimum, or those who want to moonscape their property and thus invite ex[c]essive colonization by un-irrigated invasive annuals (a concern most relevant to southern CA).”
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A second part of the wildfire science section of this opinion paper includes a discussion of the preprint of a Gollner paper focused on wildfire science. Gollner and Syphard, in a recent letter to Calfire, criticized the interpretation by LongCore and Ossola of that paper: “the authors did not appear to understand the coupled approach of reconstructive fire modeling (which incorporates calculated fuel moisture contents) and machine learning approaches applied to understand past destruction data.”
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As a comparison, what does modern wildfire science say? In April, IBHS, the preeminent source of wildfire research funding, came out with recommendations for Southern Cal here: IBHS releases Resilient Rebuilding: A Path Forward for Los Angeles, a blueprint for survivable and insurable homes and communities – Insurance Institute for Business & Home Safety. If you look at their conclusion, the first points are: “Extend Chapter 7A requirements and develop a Zone 0 standard for the entire Eaton Fire footprint. (Zone 0 is the zero-to-five-foot area immediately surrounding a structure that must be free of vegetation and any combustible items.)”
Here is a bit more wildfire science that is quite recent and that may be of help:
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This 2018 research paper shows that zone 0 regulations radically lower the possibility that a house will ignite: The evidence for Zone 0 defensible space requirements
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This 2021 research paper shows that the factors that correlate most with a house ignition are (a) wood-shingled roofs and (b) non-compliant defensible space (i.e. zone 0 and zone 1 non-compliance): What home hardening changes will help your house survive?
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These many articles show that the likeliest cause of ignition, for us, will be ember fires: What causes a home to burn?
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This article shows that, sure enough, the 1923 great Berkeley fire was an ember fire: Berkeley's Great 1923 Fire was an ember fire
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And, last but not least, this list of 10 requirements by the California Department of Insurance, which essentially spells out what you will need to do downstream when on the FAIR plan, includes, among many other things, Zone 0 requirements: Is your home prepared to receive embers to CDI standards?. Even on the FAIR plan we will eventually need to implement zone 0.
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