Human climatic and ecological drivers of Holocene fire regimes in North America

Abstract

Understanding Holocene scale fire history across North America is critical for disentangling climatic, ecological, and anthropogenic influences on fire activity. However, subcontinental fire histories remain coarsely resolved and mechanisms controlling fire dynamics are underexplored. We compiled 140 Holocene-length (12,000 years) charcoal records using a systematic database search and subsequent sensitivity analysis, comparing ecoregion-scale spatiotemporal variations with reconstructed climate parameters, global CO2 emissions, ecological productivity, and human landscape impacts to evaluate the dominant drivers of fire activity over time. Notably, we implement a novel comparison of fire history data to taphonomically-corrected archaeological data, cultural practices, and climate-human feedbacks. Results indicate that temperature, emissions, vegetation, and human impacts each drove Holocene fire activity across subcontinental North America. Furthermore, our findings suggest humans began altering fire activity as early as 6,500 cal yr BP; much earlier than previous estimates. These findings demonstrate that anthropogenic changes (i.e., population growth and fossil fuel emissions) intensify climate-related fire activity, underscoring the urgent need for resilient fire management strategies that integrate ecology and human-environment interactions.