14-4 A global calibration of sedimentary charcoal as a fire history indicator necessitates a new conceptual model and interpretative framework for the proxy

Session: Lake Sedimentary Records of Past Climate and Environment

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Abstract:

The interpretative framework of sedimentary charcoal as a fire proxy has remained largely unchanged since its inception, despite a growing body of research that challenges the assumptions inherent to this conceptual model. In this paper, we undertake a novel proxy calibration of sedimentary charcoal at the global scale using a meta-analysis of published charcoal records and satellite-derived fire history data. We use these data to test the assumptions inherent to longstanding conceptualizations of charcoal dispersal, including: size-dependent dispersal, distance-dependent deposition, and the two component model. Our analyses support the size-independence of charcoal dispersal in line with a growing body of literature and support distance-dependent deposition but also show that other factors (i.e. basin size and type, latitude) affect the absolute distance of dispersal and subsequent source area. Altogether, these results do not support both the two component model of charcoal dispersal and the validity of commonplace peak analysis of charcoal datasets. Therefore, we propose an alternative interpretive framework for sedimentary charcoal as a fire proxy that is more aligned with our analyses and the full body of published literature; a unimodal model of charcoal dispersal that exhibits distance-dependent deposition of charcoal, the absolute range of which is modulated by several fire and site characteristics.

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