Document Type

Honors Thesis

Publication Date

Summer 8-2019

Abstract

It is important to understand the response of the Antarctic Ice Sheet (AIS) to ongoing global atmospheric and oceanic warming to anticipate future sea-level change. There are several contrasting views in this regard. Harig and Simons (2015) concur with the IPCC (2013) conclusion that, in recent decades, outflow across the peripheral grounding lines of the ice sheet has exceeded increased accumulation on the interior surface of the ice sheet. In contrast, Zwally et al. (2015) suggest that recent surface accumulation in the interior East and West Antarctica has outpaced peripheral losses. They further suggest that this recent positive imbalance adds to a long-term ice-sheet thickening in interior Antarctica that began at the end of the last ice age when the increase of atmospheric temperature caused a doubling of surface accumulation that has persisted through the Holocene.

An independent glacial geologic history can provide a long-term perspective on the issue of Antarctic ice response to Holocene interglacial warming. As a contribution to this history, my study aims to develop a robust chronology of the Joyce and Garwood land-terminating alpine glaciers in Garwood Valley in the McMurdo sector of the Transantarctic Mountains. The goal is to determine whether these glaciers have expanded during the Holocene and, if so, when and why. Existing data suggest that alpine glaciers in southern Victoria Land fluctuate in concert with nearby land-terminating East Antarctic outlet glaciers, making them a useful proxy for ice-sheet behavior. Such alpine glaciers are isolated from direct marine forcing and therefore are ideal to observe Holocene behavior that may result from changes in accumulation. Here, I present a chronology of the Joyce and Garwood glacial systems from 14C dates of lacustrine algae samples within moraines and 10Be surface-exposure ages of boulder erratics on moraines. The results indicate glacier expansion since 2820 years BP and do not exclude the possibility that this expansion is ongoing.

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