Journal cover Journal topic
The Cryosphere An interactive open-access journal of the European Geosciences Union
doi:10.5194/tc-2016-271
© Author(s) 2016. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
16 Dec 2016
Review status
This discussion paper is under review for the journal The Cryosphere (TC).
Sensitivity, stability and future evolution of the world's northernmost ice cap, Hans Tausen Iskappe (Greenland)
Harry Zekollari1,2, Philippe Huybrechts1, Brice Noël3, Willem Jan van de Berg3, and Michiel R. van den Broeke3 1Earth System Science & Departement Geografie, Vrije Universiteit Brussel, Brussels, Belgium
2Laboratory of Hydraulics, Hydrology and Glaciology (VAW), ETH Zürich, Zurich, Switzerland
3Institute for Marine and Atmospheric Research, Universiteit Utrecht, Utrecht, the Netherlands
Abstract. In this study the dynamics and sensitivity to climatic forcing of Hans Tausen Iskappe (western Peary Land, Greenland) are investigated with a coupled ice flow – mass balance model. The surface mass balance is calculated from a Positive Degree-Day runoff/retention model, for which the input parameters are derived from field observations. The precipitation field is obtained from the Regional Climate Model RACMO2.3. For the ice flow a 3-D higher-order thermo-mechanical model is used, which is run at a 250 m resolution. A higher-order solution is needed to accurately represent the ice flow in the outlet glaciers. Compared to the Shallow-Ice Approximation this modifies the steady state ice cap volume by 6-8% and the area by 2–4 %. Under 1961–1990 climatic conditions a steady state ice cap is obtained that is overall similar in geometry to the present-day ice cap. Ice thickness, temperature and flow velocity in the interior agree well with observations. For the outlet glaciers a reasonable agreement with temperature and ice thickness measurements can be obtained with an additional heat source related to infiltrating meltwater. The simulations indicate that the SMB-elevation feedback has a major effect on the ice cap response time and stability. This causes the southern part of the ice cap to be extremely sensitive to a change in climatic conditions and leads to thresholds in the ice cap evolution. Under constant 2005–2014 climatic conditions the entire southern part of the ice cap cannot be sustained and the ice cap loses about 80 % of its present-day volume. The projected loss of surrounding permanent sea-ice and corresponding precipitation increase may attenuate the future mass loss, but will be insufficient to preserve the present-day ice cap for most scenarios. In a warmer and wetter climate the ice margin will retreat while the interior is projected to grow, leading to a steeper ice cap, in line with the present-day observed trends. For intermediate (+4 °C) and high warming scenarios (+8 °C) the ice cap is projected to disappear respectively around 2400 and 2200 A.D., almost irrespective of the projected precipitation regime and the simulated present-day geometry.

Citation: Zekollari, H., Huybrechts, P., Noël, B., van de Berg, W. J., and van den Broeke, M. R.: Sensitivity, stability and future evolution of the world's northernmost ice cap, Hans Tausen Iskappe (Greenland), The Cryosphere Discuss., doi:10.5194/tc-2016-271, in review, 2016.
Harry Zekollari et al.
Harry Zekollari et al.
Harry Zekollari et al.

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Short summary
In this study the dynamics of the world’s northernmost ice cap are investigated with a 3-D ice flow model. Under 1961–1990 climatic conditions an ice cap similar to the observed one is obtained, with a comparable geometry and surface velocities. The southern part of the ice cap is very unstable and under early 21st century climatic conditions this part of the ice cap fully disappears. In a projected warmer and wetter climate the ice cap will at first steepen, before eventually disappearing.
In this study the dynamics of the world’s northernmost ice cap are investigated with a 3-D ice...
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