By Jim Steele
In their Goss et al (2020) paper Climate Change Is Increasing the Likelihood of Extreme Autumn Wildfire Conditions Across California, those alarmist scientists clearly stated their intention was to make climate change the culprit by presenting an investigation that “only considers changes in climatic contributions to wildfire risk, irrespective of changes in fire ignitions, vegetation, land use or management strategies.” However, all those other factors can completely account for wildfire trends unrelated to climate change. For example, while much research has shown human ignitions have tripled the length of fire season, alarmist scientists dishonestly push a narrative that it is climate warming trends that have extended fire season. Papers not accounting for all confounding factors affecting a narrative, should never pass peer review. It is advocacy, not science! So, lets learn some science.
History shows that despite cooler and moister conditions pre-1800, an estimated ~4.5 million acres burned annually in California during the Little Ice Age (Stephens 2007). This far exceeds a 1979–1988 average of ~337,000 burnt acres/year, which then recently increased to a 21st century average of ~708,000 acres/year. However, California’s August 2020 fires did reach a similar burnt area of 4.4 million acres, when a rare swarm of thousands of dry lightning strikes ignited several small fires. Understanding the importance of vegetation analyses, reveals the great majority of lightning fires begin by igniting “fine fuels” like dead grasses, which then produce the fastest moving fires and burn the greatest area. Despite alarmists’ claims the recent increased burnt area is an indicator of climate change, vegetation changes are far more important. Burnt area is mostly determined by the presence and continuity of “fine fuels” and strong winds. But there were not any unusually strong winds when those 2020 fires began. But there has been an increase in invasive annual grasses creating greater fuel abunadance and continuity. For example, fine fuels (invasive annual grasses) have increased more than eightfold from 1990 to 2020 in the Great Basin which includes most of Nevada, half of Utah, and 10-20% of California, enabling a greater burnt area.
Understand The Critical Role of Fine Fuels
“Fine Fuels” are defined as dead vegetation less than ¼ inch in diameter. This includes cured grasses, weeds, pine needles, fallen leaves, and the small twigs of shrubs. They are also classified by fire experts as 1-hour fuels because they gain and lose moisture extremely quickly, gaining or losing 63% of their moisture in just 1 hour. Fine fuels can become highly flammable in just 60 minutes after a light rain. Climate change is totally irrelevant for fine fuel dryness and flammability.
Accordingly, 90+% of all wildfire ignitions happen in easily ignited fine fuels. Depending on the winds a grass fire, as seen in graphic A, will then rapidly spread the fire by advancing about 1 foot/second. The fire will keep advancing as long as flammable fuels are present near the flame front. However, a road may prevent the extent of grass fires, which partially explains why roadless areas experience the worst fires. Furthermore, statistics suggesting an increase in forest wildfires, obscure the fact that typically ~90–97% of the forest floor area in Sierra Nevada forests/woodlands is covered by 1-hour and 10-hour fine fuels. A grass fire’s flame front does not remain in one position for more than 5 to 15 seconds, so it moves rapidly through the forest floor without killing trees which require much more heat for a much longer time (graphic B).
However, if the fires are carried into the forests where poor land management has allowed shrubs and young trees and fine fuels to increase, the undergrowth provides ground fuels and enough fuels to release ample heat that can ignite ladder fuels and torch trees to create crown fires that emit embers that then spread the fire rapidly through the air. (graphic C & D)
Understand The Critical Role of Heat Source
Fine fuels require a heat flux (minimum rate of energy input) of 8,000–16,000 W/m² for several seconds. Higher fluxes ignite fine fuels more quickly. The flame front of an advancing grass fire releases 20,000–50,000 W/m², and that amount of heat easily dries and ignites 1-hour and 10-hour fuels, but not enough heat to burn live trees or dead logs with diameters greater than 3 inches. Multiple embers released by torched trees often collect on roofs with average heat fluxes of 15,000–80,000 W/m². Those heat sources are enough to ignite your house.
For heat flux comparisons, the sun provides at most about 1,000 W/m² of energy onto the earth’s surface on a clear day at noon. CO2’s current concentration adds less than 2.5 W/m² of energy since the Little Ice Age. However, a standard match provides about 25,000 W/m², but only for about 15 seconds. So, an arson’s match easily ignites any fine fuels and starts a wildfire. Depending on the electric current strength and other factors, a downed power line can produce 10,000 to 600,000 W/m² for several seconds to minutes. Thus, many major fires have been ignited when sparking electrical lines ignited the surrounding fine fuels. Although lightning can deliver up to a billion W/m², it only does so for less than a second. Such a short heat pulse rarely ignites a tree so primarily limits lightning’s wildfire ignitions to fine fuels.
Understand The Critical Role of Dryness
Flammability is high for most woody fuels when moisture content falls below 30%. Firewood is generally considered ready to burn efficiently below ~20–25% moisture content. Under 60% relative humidity, fine fuels commonly reach 10–20% flammable moisture content at air temperatures ranging from 30–100°F (–1 to 38°C). In contrast to claims by alarmist scientists, 1.5°C of global warming adds meaningless drying relative to the range of natural temperature fluctuations.
For example, during the rainless summer in California’s Mediterranean climate, relative humidity naturally falls and dries fine fuel’s moisture content to below 10% every day. Consider in California’s inland valleys and foothills during August, high relative humidity of 60% to 75% typically happens in the morning with temperatures in the 50s to mid-60s°F (10–19°C). Despite those cool temperatures, fine fuel moisture content reaches a very flammable 12% to 15%. As temperatures warm in the afternoon, commonly to the 80s and 90s°F (27–37°C), relative humidity falls to 30%-40%, drying fine fuels to a highly flammable 6-8% moisture content. More amazing, during the colder fall and winter temperatures when Santa Ana and Diablo wind events occur, the dry air descending from the deserts often lowers relative humidity to just 2%. Below ~10% moisture content, ignition probability from a single spark or discarded burning cigarette becomes extremely high. This evidence partially explains why despite 1.5°C cooler average temperatures during the Little Ice Age, 4.5 million acres had still burned annually in California.
To prevent rotting from fungi, exterior wood and building materials for houses range from 9% to 14% moisture content causing your house to burn more efficiently than dry firewood. Thus, we often observe neighborhoods burnt to the ground in a wildfire despite being surrounded by living trees with unaffected leaves and needles (graphic E in Paradise Camp fire and graphic F in the Dixie fire).
How to Protect Your Home from Wildfire
While so-called climate experts obfuscate wildfire science and claim you can reduce the threat of wildfire by reducing fossil fuel use, NOTHING could be further from the truth. Sadly, too many people have been lulled into wrongly thinking they are protecting their homes by buying electric vehicles or not eating meat. These obfuscating climate alarmists encourage people to stop critical thinking about how to honestly deal with wildfire threats, while useful idiots in social media advocate meaningless actions like eating bugs instead of beef.
To protect your home, simply prevent fine fuels and embers from carrying the fire into your flammable home. Create a defensible perimeter at least 5 meters away from your home by removing any fine fuels and any flammable vegetation. Don’t store flammable materials next to your home. Remove any tree branches overhanging your home and remove all low hanging branches that would provide der fuels that produce canopy fires and wind carried embers. Install fire resistant roofing and screens over all vents where embers could enter. If you understand the science of how wildfires spread, these precautions are just common sense. Alarmist climate experts be damned. Once you install these precautions, you can then guiltlessly enjoy a hamburger and fossil fuel powered heating and cooling systems.
“Climate Change Is Increasing the Likelihood of Extreme Autumn Wildfire Conditions Across California”
Wow. One of the first things taught in both my freshman Physics and Chemistry Lab courses a few decades ago was the principles behind constructing an experiment. It was emphasized that an ideal experiment was designed so that there was only one variable. It was also pointed out that there were very few ‘ideal’ experiments, so we were told to do the best we could to minimize, and ALWAYS try to characterize the variables in which we were NOT interested so their effect could be accounted for in the analysis.
I have to admit that I never thought of designing experiments to AVOID letting ‘extraneous,’ even primary, variables affect the outcome or data in order to make sure I got the result I expected.
The authors of this study not only did that, they proclaimed it. In the title. It was published in a journal that seems to be run by “Purpose-Led Publishing.” And apparently, peers reviewed and approved it for release. I sure hope this outfit’s products are filed under “Propaganda.”
Wow. Just…wow…
I think everyone has noticed that there are several journals that will publish any sort of scientific garbage, so long as it supports the “catastrophic global warming” narrative.
Actual “science” is the very last thing that matters to them.
I’d substitute many for “some” in your first sentence.
Hayman fire, Waldo Canyon, Black Forest, Marshall, Aspen acres.
Are we slow learners or what??
Drove into Springs from Denver an hour after Waldo began.
Apocalyptic!
Watched Waldo Canyon from neighbor’s deck just east of I-25, pre-evac status.
Weeks later had chance to drive through Flying W area.
One block every house but one burned to the foundation.
Block across the street w only one house gone.
Fire responders said the first thing they would do protect houses was rip the redwood decks off the structure and tear down wooden fences.
Blaming climate change for the results of bad wildlands management.
In a way, that is is correct.
It is the “climate change™” / “green” agenda that has led to many of these bad management practices.
I’m so tired of the term “wildlands”. It’s meaningless and obfuscating. To some people it means every place that isn’t urban, which is 99.9% of the Earth. In fact “wilderness” is a myth. People have resided and altered landscapes for hundreds of thousands of years.
Pre-1800 California was not a “wilderness”. It has been occupied by humans for 18+ millennia. Those humans torched the land with frequent regularity, which is why as much as 1/3 of pre-Euro California burned every year.
Of course, it’s exciting to think all the land is a mysterious wild place with wild animals and wild people doing wild stuff, and that pathetic and powerless urbanite humanity can’t do anything about it except goggle and gape in fear and amazement. But that’s not the case.
Bad language reflects bad thinking and leads to bad policies, such as the Wilderness Act that calls for “untrammeled” landscapes with no “sign of man”. Now the Feds have adopted No Touch, Let It Burn, Watch It Rot for all their lands, not just designated “wilderness”. And we also get hammered by regulations about the WUI, the Wildland Urban Interface, which is all land outside city limits. The WUI must be untouched too say the eco-Snobs.
To heck with the word “wildlands”. Use “rural” or “non-urban”. Enough with Cartoon World and dangerously ignorant language.
I appreciated the WUWT author’s description of heat fluxes to initiate ignition.
This is also easily observable when managing the “backing burn” when performing prescribed burns.
We generally start our burns at the control line or fire break that is the downwind edge of the target area. You drip torch to ignite that entire edge all at once, and then battle any flames that move downwind into or across the fire break.
As you are doing that, the backing fire slowly progresses INTO the prevailing wind by the radiant heat flux produced by the fuels. This is highly desirable for controlling a burn, because your fire break is essentially “self-widening” by that process.
It is fascinating to watch the fine fuels start steaming as the moisture is driven out of the plant material. It then begins smoking, and eventually spontaneously bursts into flame.
I have performed spring burns with frost on the ground, and the radiant heat in “clean” backing burn conditions was NOT sufficient to maintain the burn front. I have even seen this same failure (under atmospheric conditions more favorable to the fire) when burning bunch grasses that did not generate sufficient radiant heat to reliably ignite the neighboring bunches.
Conversely, I have then ignited the head fire (where the prevailing wind is driving the burn line into the fresh fuel) under the same conditions and the fire took off. This is due to two factors. First, the prevailing wind is now pushing the heated air into the fresh fuel in addition to the purely radiant heating. Secondly, any embers created by the fire line are now floating or rolling into fresh fuel and assisting in the propagation of the flame front.
I have observed very miniscule factors that will dictate whether a fire will propagate or die after initial ignition. To publish a study that deliberately excludes such factors just tells me that the “fire expert” author has almost certainly NEVER managed a fire in his entire life.
Excellent Jim as usual. You have made it so clear I don’t understand how people can still swallow the crap from the other side.
Climate Realists should never use the phrase “climate change for discussing catastrophic anthropogenic global overheating. The leftist catcall of “climate change” hides the hard to excuse lack of catastrophes, extreme temperatures, and unnatural causes that would justify the extreme measures demanded. Catastrophic anthropogenic global warming would be acceptable, but that still uses the mild term “warming” which gives no justification for the extreme measures demanded.
Note that the phrase “climate change” shows up more than 2 dozen times in the article.
Globally, fires are reducing this century. Is that because of Climate Change ??
It was a GUARANTEE THAT THE CLIMATE ALARMISTS WOULD EQUATE WILDFIRES WITH MAN-MADE CLIMATE CHANGE AND ALSO A GUARANTEE THAT THEIR SOLUTION FOR THE “PROBLEM” WOULD BE A DRASTIC REDUCTION IN THE USE OF FOSSIL FUELS. A further guarantee was that they haven’t been able to prove renewable energies would be able to supplant the energy produced by oil, coal and natural gas. But that’s OK since whatever credibility these fraudsters ever had went out the window long ago, and if they’d come clean and list where their own energy sources are coming from, they wouldn’t be from wind and solar. Nor have they purchased EVs, renounced jet travel, installed heat pumps, switched to rapid transit or embraced any of the planet-saving lifestyles that they expect the rest of us to do. All this explains the reasons that people greet climate alarmism with increasing degrees of derision.
Good to hear from you Jim.
My paddocks are bounded by Radiata pine plantation forests on two sides and a creek lined with high trees and dense foliage both sides on the other two.
This is a keeper. So far, several spring burn-offs have gone without a hitch – ignited downwind and at the leading edge a tractor wide mown area with a water-filled tanker on standby.
When is someone going to tell them about The Great Burn in 1910?