Talk by Peter Japsen and Anne Munck Solgaard – Niels Bohr Institute - University of Copenhagen

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Talk by Peter Japsen and Anne Munck Solgaard

Peter Japsen, Geological Survey of Denmark and Greenland &
Anne Munck Solgaard, Ice & Climate 

Mountain building and ice-sheet stability in Greenland 

Abstract:

Is it a justified assumption to consider the present-day bedrock topography as a fixed boundary condition for modelling of the build-up of the Greenland ice sheet? That has been the case in previous studies such as that of Letréguilly et al. (1991), Lunt et al. (2008) and Solgaard et al. (2011), but recent studies of uplift and landscape development in Greenland has shown that this assumption may not be justified for studies that consider the evelopment of the ice sheet over timescales of millions of years. Japsen et al. (2006) showed that the present-day landscape in West Greenland was formed after uplift that started only 10 million years ago. Prior to this uplift, a huge low-relief surface (a peneplain) had formed across the area as a result of fluvial erosion to base level. The peneplain was uplifted and dissected after two tectonic events at about 10 and 5 million years ago, each with a magnitude of uplift of about 1 km. This implies that the last phase of uplift may have been a necessary condition to generate sufficiently high topography for mountain glaciers and ultimately the Inland Ice to form.

This was the background for the formulation of the project Mountain building and Ice-Sheet Stability in Greenland (Miss Green) as part of the Danish IPY initiative. The project is now in its final year and we report some of the outcome of our studies. One objective for the study was to investigate if the East Greenland mountains were equally young as those in West Greenland, and we have now provided evidence to demonstrate that this is the case.

The second objective was to investigate how different topographic scenarios may affect the build-up of the Greenland Ice Sheet. We do this using temperature and precipitation patterns from AGCM experiments using Greenland topographies during different stages of the uplift to force an ice sheet model off-line. The different topographies result in different temperature and precipitation patterns influencing the conditions for build of ice in Greenland.

Japsen, P., Bonow, J.M., Green, P.F., Chalmers, J.A. and Lidmar-Bergström, K., 2006. Elevated, passive continental margins: Long-term highs or Neogene uplifts? New evidence from West Greenland. Earth Planet. Sc. Lett., 248, 315-324.

Letréguilly, A., Huybrechts, P. and N. Reeh 1991. Steady-state characteristics of the Greenland ice sheet under different climates. Journal of Glaciology, 37(125), 149-157.

Solgaard, A. M, Reeh, N., Japsen, P. and Nielsen, T. in prep. Snapshots of the Greenland ice-sheet configuration in the Pliocene to Early Pleistocene. Submitted to Journal of Glaciology.

Solgaard, A. M., Bonow, J. M., Langen, P., Japsen, P. XX. in prep. Development of the Greenland Ice Sheet under different topographic scenarios. To be included in the PhD thesis of Anne Munck Solgaard