For ages, Utah’s Great Salt Lake mirrored natural changes in climate and water flow. Recent studies reveal that over the past two centuries, human actions have transformed the lake into a state not seen in 2,000 years.
Researchers, including geoscientist Gabriel Bowen from the University of Utah, analyzed lakebed sediments to understand how the lake has evolved since it took its current form. This research sheds light on crucial historical changes, especially concerning the delicate ecosystems supported by the lake.
“Lakes are great integrators. They gather water, sediments, and nutrients,” Bowen explained. His recent study, published in Geophysical Research Letters, uses sediment records to frame today’s changes within a historical context, highlighting the challenges terminal saline lakes face.
Bowen noted that while we have extensive data about what’s happening now, vital parts of the historical picture—particularly after the arrival of white settlers—have been overlooked. This is critical as the Great Salt Lake struggles with low water levels due to drought.
Isotope analysis revealed two notable human impacts:
- Mid-1800s: With the arrival of Mormon settlers in 1847, increased irrigation transformed the landscape, feeding organic matter into the lake and altering its carbon cycle.
- Mid-20th century: The 1959 construction of the railroad causeway changed water flow between the lake’s northern and southern sections. This disruption affected salinity and water balance in significant ways.
Bowen’s team studied sediment cores to capture the lake’s story over time. The first core spans 8,000 years, illustrating conditions before settlers arrived. The second core, from just the past few hundred years, shows the lake’s changes after human influence began.
By examining carbon and oxygen isotopes, Bowen reconstructed the lake’s historical carbon and water balance. He found a marked shift in carbon sources post-settlement, indicating that organic matter from vegetation replaced mineral-based sources, dramatically changing the lake’s chemistry.
The oxygen isotope analysis unveiled how evaporation and water inflow interacted over time. Before the causeway, water levels fluctuated slightly. After 1959, the lake’s behavior changed significantly, revealing new patterns in oxygen isotopes and making some sections of the lake less salty. This adaptation bought the lake time to cope with lower water levels.
Historically, the lake has largely been in a drying state for 8,000 years. The changes brought on by human activities, particularly the railroad causeway, have altered that persistent trend and provided new avenues for understanding the lake’s health.
By uncovering these layers of history, we can better grasp current challenges and guide future preservation efforts. For more insights into the implications of these changes, check out Bowen’s full study in Geophysical Research Letters.
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Climate Change,Climate Science,University of Utah
