Fire, fuel, and climate in the Great Basin from the Middle Holocene to present from the sediments of Blue Lake, NV

Abstract

Continuous, high-resolution sedimentary records from the Great Basin are rare. By combining physical sedimentology with charcoal analysis to document changes in lake level and biomass burning, we explore the coevolution of climate and fire ecology over the past 7000 years. Elemental data from scanning X-ray fluorescence (XRF) measurements suggest persistently low lake levels during the Middle Holocene (7000–4000 cal yr BP). Two prolonged low lake stands between 4200–3800 cal yr BP and 2600–2400 cal yr BP occurred during widely documented periods of abrupt environmental change throughout the Great Basin. Significant correlations between the first principal component of the XRF record (which explains >75% of the variance) and a bristlecone pine–derived temperature reconstruction suggest warmer temperatures were a major driver of reduced precipitation–evaporation balance. Spectral analysis shows interannual and multidecadal periodicities typical of Pacific Ocean–atmosphere systems have been influential across the region after 4000 cal yr BP. Severe fire events became more commonplace as precipitation increased, highlighting the role of fuel availability on biomass burning in this semiarid region. These results suggest that while near-term warming will likely lead to increased biomass burning, prolonged periods of warmth and aridity will catalyze returns to the fire regimes of the Middle Holocene.