Antarctic Ice Sheet stability during warm periods: Integrating numerical modeling with geologic data

• Main Author: Halberstadt, Anna Ruth W
• Format: Text
• Language: unknown
• Published: ScholarWorks@UMass Amherst 2022
• Subjects: Antarctica; paleoclimate; modeling; ice sheet; glacial dynamics; past warm periods; Climate; Geology; Glaciology; Antarc*; Antarctic; Ice Sheet
• Online Access: https://scholarworks.umass.edu/dissertations_2/2527; https://doi.org/10.7275/28143430.0; https://scholarworks.umass.edu/context/dissertations_2/article/3569/viewcontent/Halberstadt_diss_submit_toGradSchool.pdf

Sea level rise is one of the major social and environmental challenges that threatens modern civilization, yet the response of polar ice sheets to future warming is deeply uncertain. Mass loss from the Antarctic Ice Sheet is projected to dominate global sea level rise in the near future, but how much, and when, remains a key unknown. The challenges associated with projecting Antarctica’s future sea level contribution are derived from a knowledge gap of physical ice sheet processes in a world warmer than today, and a lack of understanding of climatic thresholds that drive potentially irreversible retreat. Future and even modern climatic conditions are unprecedented within the last few million years; therefore, we must look to the geologic record for a glimpse of prospective Earth landscapes and climates. Past ‘warm periods’ (characterized by elevated atmospheric CO2 and surface temperatures) can provide a window into the feedbacks and instabilities that govern ice sheet dynamics under a fundamentally different climatic state. In this work, I integrate process-based ice sheet modeling, climate modeling, and remote sensing observations along with geologic data to explore the stability and behavior of the Antarctic Ice Sheet during past warm periods. In Chapter 3, I investigate Antarctic ice sheet and climate evolution during the mid-Miocene, a time period about 17 to 14 million years ago characterized by an epoch of peak global warmth followed by glacial expansion. Coupled ice sheet and climate model scenarios under varying boundary conditions provide continent-wide context for localized geologic paleoclimate and vegetation records. I combine model simulations with geologic constraints to make inferences about past CO2, tectonic uplift, and ice sheet fluctuations across this key time period. Chapter 3 has been published in EPSL (Halberstadt et al., 2021), with coauthors H. K. Chorley, R. H. Levy, T. Naish, R. M. DeConto, E. Gasson, and D. E. Kowalewski. In Chapter 4, I employ a similar modeling approach to ...