PhD defense Kristian Kjellerup Kjeldsen – University of Copenhagen

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16 May 2013

PhD defense Kristian Kjellerup Kjeldsen

Title:

Dynamics of the Greenland Ice Sheet over multiple timescales.

Time:

Tuesday, 28 May 2013 at 13:15 in the Auditorium.

Place:

Geological Museum, Øster Voldgade 5-7, 1350 Copenhagen K.

Supervisors:

Professor Kurt Kjær, Natural History Museum of Denmark

Associate Professor Svend Visbye Funder, Natural History Museum of Denmark

Assessment committee:

Professor Tom Gilbert, Chairman, Natural History Museum of Denmark

Professor Per Möller, Department of Geology, Lund University, Sweden

Professor Terry J. Wilson, The Ohio State University, USA

Dynamics of the Greenland Ice Sheet over multiple timescales

by Kristian Kjellerup Kjeldsen

Since the 1990s mass loss of the Greenland Ice Sheet has accelerated substantially increasing its contribution to global sea level rise, especially during the past decade. Even though the current global sea level budget is well understood, providing better estimates of the current and former mass losses is essential to further constrain the individual components of the budget.

In this thesis, using airborne- and satellite derived data combined with terrestrial and marine observations, the dynamic behavior of the Greenland Ice Sheet on multiple timescales is investigated. These range from annual/decadal scale variations of ice surface heights and cyclic drainage patterns of ice-dammed lakes to long-term response of the ice sheet margin during the past 300,000 years.

The results presented here show that the ice margin of the Greenland Ice Sheet responds highly dynamic and variable to climate change and oceanic forcing, with behavior additionally being governed by regional/local topographical and bathymetrical settings. Warming of ocean temperatures is suggested as being a main driver for periodic dynamic ice loss events in northwest Greenland while cooling of ocean temperatures around southern Greenland, in conjunction with increased snow accumulation, is found to drive a rapid readvance of glaciers in response to the onset of the Little Ice Age. Furthermore results suggest that the thinning pattern of the last decade in southern Greenland compares well with that of the entire 20th century, thus the present sensitivity distribution will arguably hold for future ice sheet mass loss until marine outlet glaciers become grounded and also assuming a similar warming pattern.