Antarctic Ice Mass Balance, Glacial Isostasy and Implications for Sea-level Change
Activity Rationale
Sea-level change has the potential to adversely affect Canada’s coastlines and accurate future projections require global knowledge of sources of sea-level change. This activity will result in improved analysis of Earth observations to determine the important contribution of Antarctic ice sheets and glaciers to sea-level change. The activity is part of the International Polar Year Polar Earth Observing Network (POLENET) project.
Activity leader: Dr. Tom James
The Topic
It is important to understand the past, present, and projected future contribution to sea-level change of the Antarctic ice sheet, the world's largest reserve of fresh water. In particular, the stability of the marine-based West Antarctic ice sheet, which contains enough water to cause global sea level to rise about 5 metres, has been called into question. For example, recent studies suggest an acceleration of glacial flow in a key drainage basin in West Antarctica (Pine Island Glacier).
Existing and planned GPS bedrock sites for the Polar Earth Observing Network (POLENET) project, as of Fall, 2007. For a current map see http://www.polenet.org/field_antarctic.htm
Larger image
This activity aims to better understand present-day Antarctic ice mass balance by improving observations and models of present-day crustal motion in Antarctica. It is part of the International Polar Year (IPY) Polar Earth Observing Network (POLENET), which is placing Global Positioning System (GPS) receivers on bedrock throughout West Antarctica to measure vertical crustal motion.
The information obtained from the GPS observations will be used to update a previously-developed model of vertical crustal motion in Antarctica called IJ05. The model includes the ice-sheet history since Last Glacial Maximum at about 21,000 years ago and determines the Earth’s present-day crustal movements and gravitational change due to the evolving surface load.
Remote-sensing satellite missions, such as the Gravity Recovery and Climate Experiment (GRACE) gravity satellite mission, can detect ice-mass changes. The observations, however, need to be corrected for the Earth’s response to past ice-sheet changes, which can be provided by the IJ05 model and its successors. The results of these studies will be used to assess the contribution of Antarctica to sea-level change and develop global estimates of present-day and projected sea-level change for use by planners and decision-makers
Results
A model of past Antarctic ice mass change (IJ05, Ivins and James, 2005) is routinely used by the international scientific community to “correct” satellite observations in order to determine present-day ice mass change. The analyses consistently show large on-going ice-mass change in the region of the Pine Island Glacier in West Antarctica. The IJ05 model is being improved and recent publications and presentations are focused on describing those improvements.
IJ05 model
Ivins, E.R., and James, T.S., Antarctic glacial isostatic adjustment: A new assessment, Antarctic Science, 17, 541-553, 2005.
Study Data
GPS monitoring from Antarctic POLENET stations available from UNAVCO (under "filter by Network", specify "Antarctica POLENET").
Links
International Polar Year (IPY) Polar Earth Observing Network (POLENET)
Gravity Recovery and Climate Experiment (GRACE)
Publications
Please note that subscriptions may be required for access to some articles. To request a copy of publications, or for any more information, please contact Dr. Tom James
Check for more recent publications in GEOSCAN, the publications database of the Geological Survey of Canada and the Canada Centre for Remote Sensing.
James, T.S., Measuring crustal deformation in Antarctica: GPS, tectonics, and glacio-isostatic adjustment, Newsletter for the Canadian Antarctic Research Network, 24, 1-7, 2007.
Other Materials
Simon, K M, James, T S, Ivins, E R, Wilson, T J, Willis, M, 2008. Ocean Loading Effects on Predictions of Uplift and Gravity Changes due to Glacial Isostatic Adjustment in Antarctica, Eos Trans. AGU, 89(53), Fall Meet. Suppl., Abstract G31A-0644.
Simon, K M, James, T S, Willis, M, Wilson, TJ, Ivins, E R, 2008. Effects of Regional Ocean Loading on Present-day Predicted Glacial-Isostatic Adjustment Response in Antarctica. Joint Scientific Committee on Antarctic Research/International Arctic Science Council IPY conference, July 8-11, St. Petersburg, Russia.
Ivins, E.R.; Zlotnicki , V.; Wu, X.; Gross, R.S. ; Dyurgerov, M.; Seo, K-W.; Rülke, A. ; Dietrich, R.; Scheinert, M. ; James, T.S., Reduction of GIA errors in GRACE and altimetry-based solutions for interannual ice mass balance for the Earth’s ice sheets, EGU General Assembly, Abstract no. EGU2007-A-10010, 2007.
James, TS, and ER Ivins, Crustal Motion and Gravity Change Predicted from Scenarios of Ice Mass Change in Marie Byrd Land and the Eastern Ross Sea, 2006 Fall AGU Meeting, San Francisco, CA.
Ivins, E.R.; James, T.S., GIA and ice sheet altimetry in Antarctica: How well can we quantify the associated error and its spatial dependence (solicited), EGU General Assembly, Abstract no. EGU06-A-10708, 2006.