Great Salt Lake (UT) is a hypersaline terminal lake in the US Great Basin, and the remnant of the late glacial Lake Bonneville. Holocene hydroclimate variations cannot be interpreted from the shoreline record, but instead can be investigated by proxies archived in the sediments. GLAD1-GSL00-1B was cored in 2000 and recently dated by radiocarbon for the Holocene section with the top 11 m representing ˜7 ka to present. Sediment samples every 30 cm (˜220 years) were studied for the full suite of microbial membrane lipids, including those responsive to temperature and salinity. The ACE index detects the increase in lipids of halophilic archaea, relative to generalists, as salinity increases. We find Holocene ACE values ranged from 81-98, which suggests persistent hypersalinity with <50 g/L variability across 7.2 kyr. The temperature proxy, MBT' 5Me , yields values similar to modern mean annual air temperature for months above freezing (MAF = 15.7°C) over the last 5.5 kyr. Several GDGT metrics show a step shift at 5.5 ka before which temperature estimates are unreliable due to the shift in lake ecology and likely shallow depth. The step change in lake conditions at 5.5 ka and additional variations within the late Holocene are compared to regional climate records. We find evidence for a dry mid-Holocene in GSL, corroborating other records.
Paleoclimate reconstructions of the Holocene provide insights into the stability or sensitivity of our present climate state. While it is a time of relative climatic stability compared to the glacial-interglacial cycles that preceded it, the changes may in some cases be profound especially in zones prone to drought-stress. In southwestern North America, lake sediments and speleothems record a generally wet early Holocene (11-8 ka), and a dry middle Holocene (8-4 ka) with a return to relatively moist late Holocene (Lachniet et al., 2020 and references therein). Although many Holocene climate modeling studies have struggled to simulate the mid-Holocene warmth, recent modeling has found this emerges with the addition of vegetation feedbacks (Thompson et al., 2022). As the mid-Holocene warming may be an analog for the current warming, it is studied here as context for the current drought in the region.Great Salt Lake (GSL), UT, USA, at 41.1°N is a remnant of a larger lake, Lake Bonneville. Lake Bonneville reached its maximum size during the termination of the Last Glacial Maximum (LGM) at ∼18 ka then shrank to the areal extent of modern GSL by ∼13 ka (Oviatt et al., 2021). The drying between the LGM and Holocene greatly increased salinity in the residual lake and left behind the Bonneville salt flats. This drastic shrinking and lake level drop was recorded in preserved shorelines (Oviatt et al., 2021). In contrast, any recessional shorelines of the mid-Holocene arid interval have been lost to subsequent late Holocene transgressions. Instead, continuous geochemical records from sediment cores have potential to reconstruct Holocene climate. As its name implies, GSL is salty with current salinity of 120-180 g/L (data for 2010-2021; Rupke & McDonald, 2012),
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.