Dr. Eva Lyon ((photo above on June Lake, CA) Wooster Earth Sciences Professor and Wooster Alum.) has recently published her work “A high-resolution record of Late Holocene drought in the eastern Sierra Nevada (California, USA) from June Lake carbonate geochemistry” in Quaternary Research. With the backdrop of some of the worst recent droughts being experienced in the last millennium in the American Southwest (Williams et al., 2022), Lyon and her team extends the drought history for the Sierra Nevada (Figure 1) back almost 5000 years using well-dated sediment cores from lakes (Figure 2). They used oxygen and carbon stable-isotopes rations combined with X-ray fluorescence counts of calcium and titanium to identify six intervals of past droughts.
Figure 1. (A) Regional map showing location of study area: ML, Mono Lake; SM, Stonehouse Meadow; PL, Pahranagat Lake. (B) Lakes and streams of the study area, which are found along CA State Route 158 (the June Lake Loop). Water isotope values for locations indicated by white squares (oxygen, deuterium). (C) June Lake bathymetric map. White circles indicate locations of the lake cores.
The lake record (Figure 2) that is dated using radiocarbon, reveals the dry times that include many of the famous drought in the American West including the Current Warm Period, the Medieval Climate Anomaly (about 1000 years ago, also a warm time in the West) and three pulses of drought earlier during the Late Holocene Dry Period (~3500-2000 cal yr BP). Records like these provide a perspective to the ongoing drought in the American West. Those scientists that model hydroclimate use such well-dated records of past changes in lakes as a way of better anticipating future climate. This work is particularly important as the world moves into the greenhouse climate of the future.
Figure 2. Plot of changes in core geochemistry with time. From left to right: (A) total inorganic carbon (%TIC), sampled every 2–3 cm; (B) ratio of calcium to titanium (Ca/Ti), sampled every 1 mm; (C) oxygen isotope values in per mil (δ18Ocarb), sampled every 2–3 cm where %TIC was high enough to permit measurement; (D) carbon isotope values in per mil (δ13Ccarb), sampled every 2–3 cm where %TIC was high enough to permit measurement. Here, the six dry intervals described in the text are particularly prominent as increases in oxygen isotope values—these are denoted by horizontal yellow or red bars. The horizontal blue bars indicate the wetter intervals, including the pluvial between the two peaks of the Medieval Climate Anomaly (MCA) megadrought and the Little Ice Age (LIA) (~500–100 cal yr BP, as defined in IPCC, 2021). LHDP, Late Holocene Dry Period.
Reference:
Lyon EC, Erhardt AM, Streib LC, Zimmerman SRH, McGlue MM. A high-resolution record of Late Holocene drought in the eastern Sierra Nevada (California, USA) from June Lake carbonate geochemistry. Quaternary Research. Published online 2025:1-15. doi:10.1017/qua.2024.38.
Williams, A.P., Cook, B.I., Smerdon, J.E., 2022. Rapid intensification of the emerging southwestern North American megadrought in 2020–2021. Nature Climate Change 12, 232–234.