Great Salt Lake’s history shows rapid freshwater loss
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Scientists studying sediments from Great Salt Lake in Utah reconstructed nearly 240,000 years of the lake’s history, revealing that the lake briefly transformed into a much larger, freshwater body on two occasions.
Researchers from USC Dornsife College of Letters, Arts and Sciences analysed a 400-foot sediment core to understand how the lake’s size and salinity changed over time. They dated the sediment layers using radioactive decay and examined molecules from ancient microorganisms to determine water salinity.
The team discovered that around 30,000 to 16,000 years ago, the lake expanded into Lake Bonneville, reaching a depth of approximately 1,000 feet and covering ten times the modern lake’s area. An earlier large lake, Little Valley, existed from roughly 140,000 to 135,000 years ago, though it may have been somewhat brackish and shorter-lived. These expansions occurred when cooler temperatures and increased storms brought more water into the basin, while warmer temperatures led to increased evaporation and shrinking lake levels.
Records from surrounding states like Nevada, California, and Arizona indicate similar wet-to-dry cycles during these periods, suggesting a regional climate pattern. Today, Great Salt Lake faces additional pressures from human water usage and accelerated climate change, increasing evaporation rates. Researchers caution against using the lake’s natural past fluctuations to justify its current decline, emphasizing that current warming is happening at an unprecedented rate.
