Authors: Kevin Gilmore*, HDR Engineering, Donald Sullivan, University of Denver, Maria Caffrey, Unaffiliated Climate Warrior
Topics: Paleoenvironmental Change, Human-Environment Geography, Mountain Environments
Keywords: Prehistoric Population, Drought, Climate Variability
Session Type: Poster
Presentation File: No File Uploaded
Drought has often been cited as a driver of prehistoric culture change. This study examines the importance of increased variability in climate factors that accompanies climate change as an equally important driver of culture change over the past 2000 years, with particular focus on the Medieval Climate Anomaly (MCA). Drought and climatic variability within the paleoenvironmental record of the past 2300 years derived from a sediment core from Kannah Creek Fen on Grand Mesa and PDSI reconstructed from tree-rings for the past 2000 years. Due to the relatively marginal conditions that allow subalpine fens to persist in the region, fens are very sensitive to fluctuations in climate and consequent hydrological responses, and loss on ignition at a 1 cm sampling interval provides a record of changing fen primary productivity, which has been demonstrated to correlate with fluctuations in temperature. Humification of peat, which provides a record of water table fluctuation within the fen, provides a proxy for effective precipitation. These proxies document relatively abrupt transitions between hot, dry conditions to cool, wet conditions. This paleoenvironmental record is compared to a proxy record of regional prehistoric population dynamics provided by summed probability distributions of archaeological radiocarbon dates. Our data indicate that increased interannual climate variability, even in the absence of significant changes in baseline precipitation values, can be as powerful a driver of culture change as drought alone. The combination of drought with increased variability during the MCA had a profound effect on culture and population in the eastern Colorado Plateau.