IGPP is pleased to invite you to join its Winter 2022 Seminar Series presentation featuring Tyler Pelle. Dr. Pelle's talk, "Modeling the century-scale response of Totten and Denman glaciers, East Antarctica, to future enhanced ice shelf forcing" will be available via Zoom on Tuesday, March 15, 2022, starting at 12:00pm. Zoom: https://ucsd.zoom.us/j/98764836041?pwd=UEhuOG44Y2tWY2pzNEdXM0poQi9tdz09. Password: Antarctic
Time: 12:00 pm, Pacific Time
Note: This meeting will be recorded. Please make sure that you are comfortable with this before registering.
Abstract: The East Antarctic Ice Sheet (EAIS), containing ~52 m sea level rise equivalent (SLRe) ice mass, is the largest remaining reservoir of freshwater on the planet and has been showing signs of dynamic change since at least the early 2000s. Outlet glaciers along the periphery of the EAIS have been losing mass, accelerating, and retreating in response to climate-paced forcing perturbations; yet, little is known about how these glaciers might dynamically evolve under enhanced climate-forcing conditions. In this talk, I present ice sheet modeling results that explore the century-scale evolution of the two largest ice dischargers of the EAIS: Totten and Denman glaciers. For Totten Glacier, we develop an asynchronously coupled ice-ocean model and project its evolution through 2100 under CMIP6 low and high emission scenarios. In these simulations, downstream on-shelf salinity fluctuations control the strength of the Antarctic Slope Current, which modulates warm water intrusions towards Totten Glacier. These warm water intrusions drive asynchronous patterns of retreat that culminate in a loss of 4.2 mm SLRe in high emission scenarios by 2100. To the west, ice shelf basal melting of Denman Glacier is hypothesized to be driven in-part by the outflow of fresh subglacial water across the grounding line from the grounded portion of the glacier into the sub-ice shelf ocean cavity. This process has yet to be parameterized in transient ice flow models but is theorized to be partially responsible in driving the present day changes Denman Glacier is experiencing. As such, we first develop a new melt model resolving this process and use it to force simulations of Denman Glacier through 2100 in order to determine the relative roles that subglacial hydrology and ocean forcing play on this glacier’s future evolution. We find that retreat of Denman and Scott glaciers is primarily controlled by ocean forcing, as downstream freshening after 2065 promotes warmer sub-shelf conditions and higher rates of basal melting. In high emission simulations, subglacial outflows accelerate retreat of Denman Glacier back to a topographic high that stabilizes retreat just upstream of the deepest continental trench on Earth. By 2100, Denman Glacier loses ~2 mm SLRe in high emission scenarios; however, if retreat were to reach the upstream trench, rates of ice mass loss would catastrophically increase to ~1 mm SLRe for every 5 years of retreat. Overall, our modeling results stress the sensitivity of both Totten and Denman glaciers to enhanced climate forcing while emphasizing the need for systemic monitoring of ocean conditions near the shelf break and in the vicinity of such vulnerable glaciers.