Fires that seem to have been extinguished but linger underground, smouldering unseen before breaking out again. The phenomenon is well-known but not well understood. Their increasing frequency is tied to climate change.
The best-studied examples occur in the Arctic, where summer fires that appear quenched by autumn rain can re-emerge the following spring. They are thought to owe their persistence to thick layers of peat in the soil—flammable enough to keep burning even when the land above is covered in snow and oxygen is scarce.
Investigators believe the Pacific Palisades fire of January 2025—which killed 12 people and destroyed nearly 7,000 houses and buildings in the western outskirts of Los Angeles—was itself a zombie fire. An Uber driver named Jonathan Rinderknecht was arrested in October 2025 on suspicion of deliberately starting a much smaller blaze, the Lachman fire, which burned around three hectares before firefighters believed they had extinguished it. Investigators now think the Lachman fire disappeared underground and smouldered until high winds allowed it to break out as the Palisades inferno.
California has no peat, but its chaparral ecosystems offer an alternative fuel source. Trees such as manzanita, chamise and scrub oaks survive long dry periods thanks to roots extending up to eight metres deep. These roots are tough, woody and loaded with flammable resin. The theory is that the Lachman fire burned its way down along these roots and remained there smouldering.
Thermal-imaging devices struggle to see far into soil. California's mineral-rich ground and layers of ash from previous fires act as insulators that damp the transmission of heat. The chaparral ecosystems are often found in inaccessible canyons and along steep slopes, compounding the difficulty.
Nihilism should commence with oneself.