Current Projects

Project Team: Ryan Venturelli, Jeremy Bassis (UMichigan), Sam Kachuk (UMichigan)
NSF OPP #2303344

The Antarctic Ice Sheet has not always been the same shape or size, and past changes have left behind a record of ice mass loss and gain. Our modern observational record indicates mass loss and glacial retreat responses consistent with climatic trends, but the specifics of that retreat, and our projections of future change, remain a tangle of internal dynamics of ice and its interactions with its surroundings. The challenge of making credible projections of the Antarctic contribution to sea-level change from our current generation of ice-sheet models rests on accurately reproducing past changes. This project aims to merge archived constraints on past ice-sheet behavior collected from around, above, and beneath the Antarctic Ice Sheet with a state-of-the-art ice-sheet model to improve projections of future sea-level rise. In addition, the project will support intellectual exchange between researchers across every career stage focusing on past glacial reconstructions and future projections as well as lower the barrier to entry into polar sciences by developing modular curricula to be delivered in community college classrooms and online learning environments.

With hundreds of constraints on deglacial grounding-line retreat and associated ice-surface lowering around Antarctica, the availability of paleo constraints on past ice sheet behavior no longer limits integrating these observations into modeling efforts. This project will integrate paleo-glaciological observations from the Holocene into the BISICLES model framework used to project future sea level. The goals of this project are to (i) establish the conditions that switched the mode of grounding line migration from retreat to re-advance during the mid-to-late Holocene in West Antarctica; (ii) use differences in forcing, geologic conditions, and geographic conditions between responses in the Amundsen Sea and Ross Sea embayments to investigate the differences in marine ice sheet sensitivity between an “unstable” and “stable” sector of the ice sheet; and (iii) apply the findings of (i) and (ii) to improve constraints on future sea-level projections. Investigating the interplay of external forcing, internal forcing, and geological response to ice-mass loss in West Antarctica is essential for reducing uncertainty in future sea-level-rise projections. This project will employ a multidimensional education plan focused on a mentorship structure that promotes intellectual exchange between researchers across every career stage focusing on paleo-glaciological reconstructions and future projections. The project team will co-produce three educational modules with the Colorado School of Mines Trefny Innovative Instruction Center focused on paleo-glaciological reconstruction, modern glaciological observations, and models of future sea-level rise.

Project Team: Lauren Simkins (UVA), Lindsay Prothro (TAMU-CC), Ryan Venturelli
NSF OPP #2224681

Sediments that collect on the seafloor provide a wealth of information about past and present environmental change. Around Antarctica, these seafloor sediments are influenced by an ice sheet that grinds and transports sediments from the continent?s interior into the surrounding ocean. Since the Last Glacial Maximum (about 20,000 years ago) when the ice sheet extended hundreds to thousands of kilometers seaward, ice has retreated inland to the configuration we observe today and left behind signatures of its growth and decline, as well as indicators of ocean change, in the seafloor sediments. Ongoing glacial and ocean processes are reflected in the characteristics of contemporary sediments, whereas older sediments beneath the seafloor offer a longer temporal perspective of changes to the ice sheet and surrounding ocean. Using data generated from archived sediment cores that are predominantly housed in the Antarctic Core Collection at Oregon State University, we aim to confirm if recent sediments clearly reflect the specific instrumental and historical field-based observations of ocean and glacial change seen in different regions of Antarctica. These modern changes will be placed into context with those recorded by sediments deposited on the seafloor hundreds to thousands of years ago.

This project will explore interlinked physical, biological, and geochemical properties of seafloor sediments to address the influence of glacial and oceanographic processes on ice-proximal marine sedimentation during the 20th and 21st centuries and since the Last Glacial Maximum, with a focus on sediment fluxes, meltwater drainage, ice-rafted debris deposition, and radiocarbon chronologies. We will integrate multi-proxy analyses to interrogate the seafloor sediment record around Antarctica, targeting regions offshore of relatively fast-flowing and fast-changing glacial systems today and regions offshore of slower flowing, more stable (i.e., unchanging or relatively minimally changing) parts of the ice sheet. This work will leverage the application of new techniques and knowledge to legacy sediment cores that NSF has invested greatly in collecting and archiving. This project is led by three early-career women project investigators who seek to foster collaborative and open research practices and professional growth of the project team which will include three graduate students, numerous undergraduate students, and a postdoctoral research associate. The project team will co-produce educational materials with Math4Science, an organization that connects STEM professionals with public secondary education students and their math and science teachers through curricula; and develop and implement best practices in working with marine sediment core data through a collaboration with the Oregon State University Marine and Geology Repository and the United States Antarctic Program – Data Center.

PI: Dr. Marion McKenzie
NSF EAR Postdoctoral Fellowship #2305317

The deglacial history of Cordilleran Ice Sheet (CIS) marine margins over the last 50,000 years is poorly constrained despite the potential insights this record may contribute to identifying controls on ice stream stability, elucidating millennial and global-scale climate oscillations, and characterizing paleo-current dynamics across the Pacific Ocean. The proposed project will leverage techniques from the fields of sedimentology, geochronology, geophysics, and glaciology to constrain the spatiotemporal retreat dynamics of relict ice streams near the Queen Charlotte Sound. Principally, the researchers will supplement mapping of glacial geomorphic landforms from LiDAR and bathymetric elevation data with iceberg-rafted debris (IRD) and offshore marine sediment geochronology from Deep Sea Drilling Project (DSDP) cruise 18, site 177 to constrain the location, behavior, timing, and rate of southwestern CIS ice stream activity over the last 50,000 years. Pairing on-and-offshore data will lead to strong temporal and spatial records of paleo-glaciation with implications for overall CIS modelling, ocean dynamics in the Pacific Ocean, and millennial-scale climate oscillations to bolster understanding of dynamics, rates, and magnitude of change in the Earth climate system. Multidisciplinary techniques used throughout this work will improve understanding of controls on ice streams suitable for predicting dynamics of future ice loss to ultimately elucidate the relationship between onshore and offshore records. 

US Project Team: Greg Balco (BGC), Brenda Hall and Seth Campbell (UMaine), Ryan Venturelli
UK Project Team: Joanne Johnson (BAS), John Woodward (Northumbria), Dylan Rood (Imperial College London)
NSF OPP #2317097

This project contributes to the joint initiative launched by the U.S. National Science Foundation (NSF) and the U.K. Natural Environment Research Council (NERC) to substantially improve decadal and longer-term projections of ice loss and sea-level rise originating from Thwaites Glacier in West Antarctica. The Thwaites Glacier system dominates the contribution to sea-level rise from Antarctica. Predicting how this system will evolve in coming decades, and thereby its likely contribution to sea level, requires detailed understanding of how it has responded to changes in climate and oceanographic conditions in the past. This project will provide a record of regional sea-level change by establishing chronologies for raised marine beaches as well as the timing and duration of periods of retreat of Thwaites Glacier during the past 10,000 years by sampling and dating bedrock presently covered by Thwaites Glacier via subglacial drilling. Together with climatic and oceanographic conditions from other records, these will provide boundary conditions for past-to-present model simulations as well as those used to predict future glacier changes under a range of climate scenarios. Specifically, the project will test the hypothesis–implied by existing geological evidence from the region–that present rapid retreat of the Thwaites Glacier system is reversible.

The team aims to utilize two approaches: 1. To reconstruct relative sea level during the Holocene, it will map and date raised marine and shoreline deposits throughout Pine Island Bay. Chronological constraints on sea-level change will be provided by radiocarbon dating of organic material in landforms and sediments that are genetically related to past sea level, such as shell fragments, bones of marine fauna, and penguin guano. 2. To obtain geological evidence for past episodes of grounding-line retreat, the team will apply cosmogenic-nuclide exposure-dating of subglacial bedrock. Using drill systems recently developed for subglacial bedrock recovery, the team will obtain subglacial bedrock from sites where ice thickness is dynamically linked to grounding-line position in the Thwaites system (specifically in the Hudson Mountains, and near Mount Murphy). Observation of significant cosmogenic-nuclide concentrations–the team will primarily measure Beryllium-10 and in situ Carbon-14–in these samples would provide direct, unambiguous evidence for past episodes of thinning linked to grounding-line retreat as well as constraints on their timing and duration.