Collaborative Research: RUI: Glacier resilience during the Holocene and late Pleistocene in northern California

Global temperature rise since 20 ka and during the last century has caused glaciers to retreat and disappear throughout the world. Some glaciers, however, continue to persist today, and highlight the importance of precipitation on maintaining glaciers in a warming climate. The Trinity Alps Wilderness in the Klamath Mountains, northern California provides evidence for multiple glacial advances since the Last Glacial Maximum (LGM; ~26-19 ka) at relatively low elevation (<3000 m) and low latitude (41°N). Moreover, the Klamath Mountains are located within 100 km of the Pacific Ocean that provides a wetter and warmer climate than the well-studied continental settings of the U.S. (e.g., The Rocky Mountains). This project aims to understand the climatic controls on glacier retreat and growth within the Trinity Alps, and investigate the sensitivity of glaciers to these climate changes. We hypothesize that 1) high precipitation within the Pacific-proximal Trinity Alps may have overprinted temperature rise and slowed glacier retreat after the LGM until at least 15 ka, and 2) precipitation increases after ~700 yr BP caused Little Ice Age glaciers to form in the Trinity Alps along northern cirque margins where glaciers were insulated from solar radiation. To test these hypotheses, this collaborative proposal will reconstruct the climate and glacier history of the Trinity Alps utilizing new lake-core records, dendrochronology, and 10Be cosmogenic dating of glacial features. These data will be combined with numerical modeling and historical climate data to document the controls on glacier growth at the millennial and sub-millennial timescale.