Investigating the response of Greenland and Antarctic glaciers to atmospheric and oceanic forcings using a 1D flowline model

Abstract

Over the past two decades, the mass loss from the Antarctic and Greenland ice sheets has contributed approximately 11.2 ~3.8 mm to global mean sea level, one third of the total sea level rise since the 1990s. The majority of this mass loss has come from the acceleration of tidewater outlet glaciers, through mechanisms that are poorly understood. While we know that the recent increase in mass loss is due to climate changes, questions remain about the processes that both destabilize and stabilize glaciers. Being able to characterize these processes is essential for producing realistic ice sheet mass balance predictions. In this dissertation, we use a width average (1-D) flowline model to investigate the current and past behavior of glaciers in both Antarctica and Greenland, with the broader goal of understanding how they respond to increased climate variability. In the first chapter, we show that the unique behavior of Helheim Glacier in East Greenland is driven primarily by atmospheric, not ocean variability. In the second chapter, we address the role of glacier geometry in modulating decadal-scale dynamics of Greenland glaciers. Our results show that, contrary to many assumptions, width and bed topography only play a small role in controlling mass loss during retreat. The third chapter focuses on the retreat of Byrd Glacier, East Antarctica from its grounding line during the Last Glacial Maximum (LGM), to its current configuration, under rising atmospheric and oceanic temperatures. We show that atmospheric changes are the primary driver for the retreat, and that the current geometry of the Ross Ice Shelf has been similar for the last 2,000 years. The results of this thesis increase our knowledge of Greenland and Antarctic glacier dynamics, their relationship with atmospheric and oceanic forcings, and their future contribution to sea-level.