10Be Dating Constraints on the Deglaciation History of the Juneau Icefield

Understanding how glaciers responded to climate forcing during the Last Glacial Maximum (LGM) and its subsequent deglaciation provides insight to how today's glaciers will respond to an increasingly warming climate. While detailed reconstructions of mountain glacier change during the post-LGM deglaciation exist around the globe, deglaciation histories from high northern latitudes are relatively sparse due to complete coverage of continental ice in such regions. Fortunately, Alaska was only partially glaciated during the LGM, making Alaska one of the few high latitude regions with detailed geomorphic records of mountain glacier extent and retreat during the LGM and subsequent deglaciation. However, post-LGM deglaciation is poorly constrained in Southeastern Alaska. We contribute to this gap with new estimates of glacier elevation change on the Juneau Icefield (SE Alaska and NW British Columbia) using cosmogenic 10Be minimum exposure dating. We compare these 10Be dates with the post-LGM deglaciation timescale to constrain the rate and timing of SE Alaskan glacier thinning in response to post-LGM climate forcing. These results not only contribute to filling the spatial gap in Alaska's last deglaciation history, but they also provide insight into how temperate glaciers will respond to present-day climate forcing.