Paper No. 4
Presentation Time: 9:00 AM


POWELL, Ross D., Department of Geology & Environmental Geosciences, Northern Illinois University, De Kalb, IL 60115,

Grounding-line stability of marine-ending glaciers is of concern due to their importance in influencing rates of sea level rise during global warming by governing rates of ice mass loss. Tidewater and floating grounding zones have similar processes acting, but their relative magnitudes vary between these two end members with consequent differences in terms of their influence on grounding-line stability. Processes considered Important for this discussion are ice dynamics, ice surface melting and crevassing, ocean dynamics, subglacial sediment and water dynamics, and subglacial bed geometries. Mark Meier was a leader in collecting field data and making direct observations, but many more reliable field measurements and data continue to be needed because there are still too few to properly constrain the range of boundary conditions in this complicated system. Some data will be presented covering a range of regimes from Alaska, Svalbard and Antarctica with emphasis on subglacial sediment/water dynamics and fluxes. However, more data are required on these processes too to fully represent the spectrum of glacial regimes and to assess the significance of grounding-zone sediment systems in counteracting the other processes to force grounding-line stability. At present our data indicate that grounding-line stability driven by subglacial sediment/water flux it is likely to be of limited duration if other variables remain constant.