Holocene black carbon burial and wildfire activity on the Laptev Sea shelf

Wildfires increasingly influence climate dynamics and carbon cycling in the rapidly warming Arctic. However, long-term Arctic wildfire reconstructions remain uncertain due to complex sedimentary processes and “old” carbon, which may obscure primary fire signals. Here, we reconstructed Holocene wildfire variability and investigated black carbon (BC) burial mechanisms on the Laptev Sea shelf by combining BC fluxes with molecular-level benzene polycarboxylic acid (BPCA) proxies. During the cold and dry phase (12–10.4 ka BP), wildfires were limited by low fuel availability, whereas early Holocene warming (10.4–8.2 ka BP) likely intensified fire occurrence. BPCA signatures implied that enhanced BC burial during this interval resulted from both fresh biomasses burning and the remobilization of “old” BC released from thawing permafrost, supporting a positive feedback loop that linking climate warming, wildfire, and permafrost degradation. During the humid Holocene climate optimum (8.2–5 ka BP), BC records primarily reflected long-distance transport from the Siberian interior. Although forest expansion likely increased fuel availability, wetter conditions and peatland development favored low-efficiency smoldering combustion. Late Holocene (5–0 ka BP) BC fluxes might be influenced by sedimentary redistribution processes, particularly anchor ice transport, which might decouple BC burial from contemporaneous fire activity. Overall, our results revealed a climate-sensitive wildfire regime in the Siberian Arctic, with fire activity enhanced during warm intervals and suppressed during cooler phases, while moisture partially modulated combustion efficiency. These findings highlighted that reliable Arctic wildfire reconstructions require considering sedimentary dynamics and permafrost-derived “old” carbon, essential for assessing climate-fire-permafrost interactions and carbon cycle responses to ongoing warming.