California and the Western United States are no strangers to fire, but this week's awful wildfires in the Los Angeles area have taken the destruction inside one of America's greatest cities.
Key themes from this episode include the complex interplay of natural and human factors in wildfire ignition and spread, the unintended consequences of past fire suppression policies, the escalating impact of climate change, the unique challenges presented by Southern California's weather patterns, and the devastating impacts of wildfires on both the natural environment and human communities.
Key Themes and Findings --
Historical Context and Policy Missteps:
The 1910 firestorm in the Western US led to a policy of aggressive fire suppression by the US Forest Service. While initially effective, this has had unintended long-term consequences.
The suppression of low-intensity fires has allowed for the accumulation of fuel (dead leaves, branches, etc.), making forests more vulnerable to severe, high-intensity fires. As one source notes, "Low burning fires clear the forest floor and lower branches from trees. Then, if a more intense fire moves through the same area, it’s slowed by a lack of fuel."
The lack of regular, low-intensity burns disrupts the natural fire cycle that is beneficial for many ecosystems.
Factors Influencing Fire Spread:
Fuel Load: The amount and type of vegetation is a major determinant of fire spread and intensity. This includes not just surface fuels, but also "ladder fuels" that allow fire to reach the forest canopy.
Weather Conditions: Hot, dry, and windy conditions are conducive to wildfire development. In California, Santa Ana winds play a significant role in spreading fires and embers (which can spark new spot fires far away.) As one source notes, "The air of the Santa Ana winds is unusually dry because it originates in the desert environment of the Great Basin."
Topography: Land shape impacts the availability of sunlight, water, and the speed of fire spread, with steep slopes often accelerating fire movement.
Moisture Content is crucial; dry vegetation burns much more easily, and some sources noted extreme dryness in Southern California this year.
Embers: Embers blown by high winds can ignite spot fires well ahead of the main fire front. As one source notes, "embers from the fire flames were being blown more than a mile...spark[ing] new spotfires."
Climate Change Amplification:
Climate change is intensifying the risk of wildfires globally, with hotter, drier conditions and more extreme weather patterns. A quote from one of the sources notes that "Climatic cycles with wet periods that create substantial fuels, followed by drought and heat, often precede severe wildfires. These cycles have been intensified by climate change."
Multiple sources noted that 16 of the 20 most destructive fires on record in California have occurred in the past decade.
There is a climate pattern, caused by a ridge of high pressure, that is deflecting storms away from Southern California which leads to drier conditions in the south and wetter ones in the north.
Wildfires in California:
California experiences severe wildfires due to its dry climate, hot summers, and frequent winds. Historically, before 1800, up to 11.9 million acres burned annually. Currently, since 2000, the annual area burned has ranged from about 90,000 to 1,590,000 acres, with the 2020 wildfire season burning nearly 4.5 million acres.
The August Complex fire in 2020 consumed over 1 million acres, the largest in California history. Many of the largest fires on record have occurred in the past decade.
Some areas of California experience repeated ignitions and fires.
Southern California is experiencing extremely dry conditions this year, with downtown Los Angeles having received just 0.16 inches of rain since October 1, while the normal amount should be 4.56 inches.
Ecological Impacts and Benefits:
Wildfires can expose nutrient-rich soil, which supports seed germination and promotes the growth of new vegetation.
Many plant species have evolved with fire and depend on it for their life cycle.
However, increased fire frequency can damage native plant communities and promote invasive, highly flammable species.
Impacts on Human Communities:
Direct Risks Wildfires cause significant property damage and can lead to displacement of communities. People who live in areas near wildfires should be prepared to evacuate, keeping vital documents and medicines readily accessible.
Looting: Looting is a problem during evacuations, and law enforcement has warned against those committing such crimes, as the consequences are severe.
Air Quality: Wildfire smoke poses significant health risks due to the presence of particulate matter, carbon monoxide, and other harmful substances. This can cause or exacerbate respiratory issues such as asthma. One source notes that "80–90% of wildfire smoke, by mass, is within the fine particle size class of 2.5 micrometers in diameter or smaller."
Water Quality Wildfires and their debris can severely impact the quality of drinking water.
Post-Fire Risks: Even after a fire is extinguished, dangers remain, including falling trees, ash pits, and contamination of water systems.
Wildfire Management and Mitigation:
Prevention: Measures include reducing fuel loads through controlled burns and thinning, enforcing building codes, and maintaining defensible spaces around structures.
Detection: Emerging technologies, including local sensor networks (temperature, humidity, smoke) and AI powered cameras, are being used to provide early detection. Satellite and aerial monitoring also play crucial roles in identifying and tracking fires. One source notes that PanoAI is installing "360 degree 'rapid detection' cameras around the Pacific northwest, which are mounted on cell towers and are capable of 24/7 monitoring of a 15 mile radius".
Suppression: Fire retardants are used to slow fires, but concerns remain about their impact on water quality. Wildfire modeling helps predict fire behavior to enhance the safety of firefighters and the public.
Wildland Fire Use (WFU) and Prescribed Burns: Allowing naturally occurring fires to burn in specific circumstances and conducting controlled burns are recognized as important tools for maintaining healthy ecosystems.
Santa Ana Winds:
These winds are created by high pressure in the Great Basin, forcing air through mountain passes and down to the Southern California coast.
The air is dry and warms as it moves down the mountains, making it a dangerous condition for wildfires. The winds can also lift embers, thus spreading fires.
Getty Fire Mitigation
The Getty Museum is a case study in how museums in fire-prone areas must act to mitigate risk, by having cleared brush, maintaining a private water supply, and having tanks for water (50,000 gallon and 1 million gallon tanks at their two campuses.)
Key Quotes:
"If you are thinking about coming into any of these areas to steal from our residents, I'm going to tell you something: you're going to be caught, you're going to be arrested, and you're going to be prosecuted," - Sheriff Luna highlights the threat of looting and the authorities' plans to prosecute offenders.
"Simply put, this is a hellscape...There are so many homes on fire it's unusual to see a home that is not." - Jonathan Vigliotti's description of the scene, highlighting the devastation of recent fires.
"I don’t even know what to say — devastating — there’s no word for this. This is historic, and beyond.” - Capt. Sheila Kelliher Berkoh, highlighting the magnitude of the devastation in Malibu.
"You need to be prepared...if you are told to evacuate and given an order, there is nothing worth your life." - Sheriff Luna highlighting the need for preparedness.
"The fire threat has increased greatly in California and other parts of the West amid a hotter and drier climate and an expansion of homes into the wildland areas surrounding major cities." - Reflecting the interconnectedness of climate, development and fire risk.
"In fact, many plant species depend on the effects of fire for growth and reproduction." - Highlighting the important ecological role of fire.
Wildfires are a complex challenge that requires a multifaceted approach. Addressing the issue will involve not only improving fire detection and suppression but also revising historical fire management practices, mitigating the impacts of climate change, addressing the unique weather patterns of Southern California, and working with communities to reduce risk.