Two Sites in East Asia Add to Spatiotemporal Heterogeneity of Wildfire Activity Across the Paleocene–Eocene Thermal Maximum

The Paleocene–Eocene Thermal Maximum (PETM; ∼56 Ma) was a period of extreme global warming associated with a massive influx of isotopically light carbon into the ocean–atmosphere system. The burning of Paleocene peatland (wildfire hypothesis) has been proposed as a potential light carbon source. In addition, numerical models have predicted that wildfire activity would intensify in response to CO₂-induced global warming. In this study, we tested the wildfire hypothesis and model prediction by tracing the wildfire history across the PETM in East Asia using polycyclic aromatic hydrocarbons (PAHs). The PAH record exhibited notable spatiotemporal heterogeneity, indicating that wildfire activity varied widely across different regions and time periods during the PETM and highlighting the complex interplay between climate, vegetation, and fire dynamics. Global wildfire records do not support the global burning of Paleocene peatland; therefore, a wildfire-related light carbon source requires close scrutiny.