Wildfires destabilize permafrost critical zones in northern high latitudes

Abstract Northern high-latitude permafrost is facing unprecedented wildfire disturbances, driving an anomalous regional increase in annual carbon emissions (8.1 ± 2.9 TgC yr⁻¹ from 1997 to 2023) against a backdrop of declining global wildfire emissions. To elucidate these complex dynamics, this review conceptualizes the “Permafrost Critical Zone” (PCZ) and adopts a holistic Earth-system perspective to evaluate the cascading impacts of wildfires on vulnerable cryospheric landscapes. We synthesize how fire-induced organic layer combustion and surface albedo reduction destabilize the PCZ, drastically elevating ground surface temperatures by up to 7 °C and deepening the active layer by up to six times. These severe thermal shocks fundamentally rewire hydrological pathways, accelerating ground ice melt, altering supra-permafrost water storage, and amplifying surface runoff. Concurrently, wildfires abruptly reduce microbial diversity and restructure cold-adapted biological communities, initiating divergent post-fire vegetation succession trajectories. While ecological and hydrothermal recovery is essential for restoring carbon and water fluxes, the compounding effects of repeated fires under a warming climate threaten to irreversibly degrade these environments. We conclude by highlighting critical knowledge gaps and emphasizing the necessity of integrating PCZ dynamics into global models to predict impending climate tipping points and to inform long-term sustainable development strategies.