ONLINE: Drivers of Hot and Cold Past Wet States Recorded by Lakes in the Western United States

press release: Dan Ibarra, UC Berkeley

G.K. Gilbert’s 1890 monograph on Lake Bonneville for the United States Geological Survey 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. 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 southwest. These inferences provide quantitative targets for assessing the performance of climate model simulations of the terrestrial water cycle.

All Yi-Fu Tuan Lecture Series presentations arefully online via Zoom every Friday at 3:30 PM. The link to join the meeting is https://uwmadison.zoom.us/j/96180090381 except when otherwise indicated. Brown bag sessions start at noon on the days there are speakers. Alumni, friends and the public are always invited to attend.