5-7 July 2008, St. Petersburg
The current generation of prognostic ice-sheet models fails to adequately capture rapid and non-linear responses of the polar ice masses to environmental forcings, such as dramatic increase in ice discharge following weakening and disintegration of buttressing ice shelves and ice tongues. While the Intergovernmental Panel on Climate Change acknowledged the potential importance of ice-dynamical effects, processes that could render the Greenland and Antarctic ice sheets more vulnerable to future warming are not incorporated into forecasts of future sea-level rise, primarily because of limited understanding of the processes involved. The challenge facing the glaciological community is to move beyond the prevailing “shallow ice paradigm” – which necessarily produces sluggish ice masses – and to develop the next generation of models that include non-linear processes in a more realistic manner. To achieve this goal, a concerted community effort will be needed that involves targeted data collection and interpretation for better process understanding, novel modeling approaches to incorporate processes acting over small spatial scales into models simulating the evolution of entire ice sheets, and model evaluation against current behavior as well as paleo-reconstructions. Many of the controlling processes are not well understood. Particular challenges include documenting and analyzing the response of grounded outlet glaciers and ice streams to ice-marginal forcings, and how this response may be modulated by bed topography and ice-dynamical flow adjustments. Fortuitously, ongoing ice shelf collapse in the Antarctic Peninsula as well as collapse of floating fjord glaciers in Greenland, offer the opportunity to study grounding-line instability at various stages of ice-shelf retreat and collapse. Coupled with advances in remote-sensing techniques that allow us to better constrain the geological nature of the bed, and geothermal heat supplied to the basal ice, major advances in understanding physical processes are possible through concerted multi- disciplinary efforts that involve both targeted field campaigns and theoretical developments and data interpretation.
Recognising the importance of a targeted interdisciplinary approach to address inadequacies in current efforts to model the disintegration of ice sheets in response to a warming climate, a Workshop is considered timely to develop a community strategy on how best to (i) improve the physical understanding of ice sheet processes responsible for rapid change; (ii) incorporate improved physical understanding into numerical models; (iii) assimilate appropriate data into the models for calibration and validation; and (iv) develop prognostic whole ice-sheet models that better incorporate non-linear ice-sheet response to environmental forcings (such as change in surface mass balance, loss of buttressing from floating ice shelves and ice tongues, and rising sea level).
The Workshop was scheduled immediately prior to the SCAR/IASC Open Science Conference, St. Petersburg, Russia, and involved one day of invited presentations, followed by one day of discussions and writing in break-out groups, and half a day of concluding plenary discussions. Approximately 50 participants from diverse disciplines including glaciology, high-latitude oceanography and meteorology, geophysics, representing both modelling and observational communities were present.
Summary statement from the Workshop on Understanding Sea-Level Rise and Variability, June 2006
Report of the Workshop on Ice Sheet Modelling, held at NOAA’s Geophysical Fluid Dynamics Laboratory (GFDL) on 8 January 2007
A Need For More Realistic Ice-Sheet Models, SCAR Report 30, December 2007