| Summary: | Ph.D. Mountain glaciers and ice caps are an integral part of the Earth’s climate system yet the Holocene history of mountain glacier variability remains poorly known, particularly in remote regions of the Arctic. In Greenland, for example, continuous records of Holocene alpine glacier change are extremely rare, and the majority of information regarding past glacier extents is fragmentary. While contemporary observations are critical for understanding the mechanisms driving present-day glacier change, geological reconstructions of former glacier fluctuations provide additional data on glacier behavior over longer timescales, and place much-needed constraints on the sensitivity of glacier response to climate change. Here, I employ a novel multi-proxy approach that combines glacier-fed lake sediments, radiocarbon dating of in situ moss that recently emerged along retreating ice cap margins, and cosmogenic in situ 10Be and 14C surface-exposure dating to reconstruct centennial-scale records of Holocene mountain glacier fluctuations in West Greenland. This investigation also merges pre-historic glacier records with contemporary observations; historical aerial photographs and satellite imagery provide 20-21st century glacier length histories that shed light on the intricate processes that link glaciers and climate. The glacier-size records developed here reveal a sdynamic response of mountain glaciers to Holocene climate variability in West Greenland; glaciers episodically advanced and retreated at centennial-timescales despite the progressive insolation-driven millennial-scale cooling trend during the Holocene in the Northern Hemisphere. Radiocarbon-dated glacier-fed lake sediments from two regions in West Greenland suggest that abrupt cooling at 9300 and 8200 years ago, recorded in Greenland ice core, triggered advances of glaciers that are contemporaneous with advances/stillstands of the western GrIS margin. Following decreased glacier activity in the middle Holocene, several independent glacier-size proxies ...
|
|---|