Environmental Science and Engineering Seminar

Wednesday, April 7, 2021
4:00pm to 5:00pm
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Online Event
Lacustrine records of Cenozoic and Plio-Pleistocene hydroclimate change in western North America
Daniel Ibarra, University of California Berkeley,

Studies of Lake Bonneville in the late 1800s initiated over a century of research on Quaternary lakes in the American west. The continuation of this work is increasingly pertinent with the need to test climate models used to forecast future water resources in the region as the climate warms, resulting in a renewed focus on older lake systems. Importantly the presence or absence of lakes in terminal basins provide an unequivocal measure of wetness. In this work I will show that wetter conditions during both colder- and warmer-than-present periods in the past are recorded in shoreline and outcrop data from the latest Pleistocene and the middle-Pliocene. Using hydrologic scaling relationships, I demonstrate that: 1) Pleistocene lakes during glacial maxima in the northern Great Basin do not require substantial precipitation increases to explain many lake shoreline extents; and 2) middle-Pliocene lakes would have required up to a doubling of precipitation in the southern Great Basin. These inferences provide quantitative targets for assessing the performance of climate model simulations of the terrestrial water cycle. Additionally, I will show ongoing work that is part of my postdoctoral research testing these modeling results using carbonate clumped isotope paleothermometry and lacustrine chert triple oxygen isotope analyses to constrain past water balance in Pliocene and Eocene lake systems in the western

For more information, please contact Bronagh Glaser by email at bglaser@caltech.edu or visit Environmental Science and Engineering.