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Understanding the causes and future direction of the present rapid thinning of Jakobshavn Isbrae, Greenland

English title Understanding the causes and future direction of the present rapid thinning of Jakobshavn Isbrae, Greenland
Applicant Lüthi Martin Peter
Number 113503
Funding scheme Project funding
Research institution Versuchsanstalt für Wasserbau, Hydrologie und Glaziologie ETH Zürich
Institution of higher education ETH Zurich - ETHZ
Main discipline Hydrology, Limnology, Glaciology
Start/End 01.04.2007 - 31.03.2010
Approved amount 161'240.00
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Keywords (10)

glaciology; ice stream; glacier dynamics; sea level rise; numerics; Greenland; Jakobshavn; ice stream dynamics; finite element modeling; sea level change

Lay Summary (English)

Lead
Lay summary
Jakobshavn Isbrae is the fastest of three large outlet glaciers known to be thinning rapidly in Greenland. Jakobshavn Isbrae underwent dramatic changes in the last 10 years. Coinciding with surface drawdown was the retreat of the calving front by 10 km, and a doubling of flow speed to approx. 14 km/year.

We will extract a detailed quantitative flow history of this system from the GPS measurements, satellite imagery, and aerial photography, spanning 20 years. These measurements will be interpreted through finite element modeling efforts designed to address the three dimensional nature of the ice flow in this system, requiring a full solution of the mass, momentum and energy balance equations.

We will determine the role of ice dynamics in the thinning seen in this system, and therefore bracket the contributions of surface mass balance and basal melting; we will quantify the flow resistance provided by the rapidly disappearing floating tongue in this system, thus addressing connections to possible ocean forcing; and we will measure the ongoing changes in the velocity field in detail, so that modeling may more effectively limit the possible directions of the future evolution of this system. In addressing all of these goals with a coordinated field, remote sensing, and modeling effort, we will make progress toward the goal of understanding changes in the mass of the Earth's ice cover and the potential impact of those changes on sea level and society.

[The project is conducted in close collaboration with NASA-funded project with the same title.]
Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Employees

Publications

Publication
Quantifying velocity response to ocean tides and calving near the terminus of Jakobshavn Isbræ, Greenland
David Podrasky, Martin Truffer, Martin Lüthi, Mark Fahnestock (2014), Quantifying velocity response to ocean tides and calving near the terminus of Jakobshavn Isbræ, Greenland, in Journal of Glaciology, 60(222), 609-620.
Achieving textbook multigrid efficiency for hydrostatic ice sheet flow
Brown Jed, Smith Barry, Ahmadia Aron (2013), Achieving textbook multigrid efficiency for hydrostatic ice sheet flow, in SIAM J. Sci. Comput., 35(2), 359-375.
Observing calving-generated ocean waves with coastal broadband seismometers, Jakobshavn Isbræ, Greenland
Amundson Jason M., Clinton John F., Fahnestock Mark, Truffer Martin, Lüthi Martin P., Motyka Roman J. (2012), Observing calving-generated ocean waves with coastal broadband seismometers, Jakobshavn Isbræ, Greenland, in Annals of Glaciology, 60(53), 79-84.
Computational methods for ice flow simulation
Brown Jedediah (2011), Computational methods for ice flow simulation, ETH Zurich, Zurich, Switzerland.
Ice mélange dynamics and implications for terminus stability, Jakobshavn Isbræ, Greenland
Amundson J. M., Fahnestock M., Truffer M., Brown J., Lüthi M. P., Motyka R. J. (2010), Ice mélange dynamics and implications for terminus stability, Jakobshavn Isbræ, Greenland, in Journal of Geophysical Research, 115(F1), F01005-F01005.
Calving icebergs indicate a thick layer of temperate ice at the base of Jakobshavn Isbræ, Greenland
Lüthi Martin P., Fahnestock Mark, Truffer Martin (2009), Calving icebergs indicate a thick layer of temperate ice at the base of Jakobshavn Isbræ, Greenland, in Journal of Glaciolgoy, 55(191), 563-566.
Transient response of idealized glaciers to climate variations
Lüthi M. P. (2009), Transient response of idealized glaciers to climate variations, in Journal of Glaciology, 55(193), 918-930.

Associated projects

Number Title Start Funding scheme
197015 Comprehensive Observations of Episodic Basal, Englacial and Lateral Influences on Ice Stream Dynamics 01.03.2021 Project funding
156098 Understanding long-term outlet glacier calving dynamics with a combined high-resolution field,- remote-sensing- and modeling approach. 01.03.2015 Project funding
129898 Extension: Understanding the causes and future direction of the present rapid thinning of Jakobshavn Isbræ, Greenland 01.04.2010 Project funding
129898 Extension: Understanding the causes and future direction of the present rapid thinning of Jakobshavn Isbræ, Greenland 01.04.2010 Project funding
197015 Comprehensive Observations of Episodic Basal, Englacial and Lateral Influences on Ice Stream Dynamics 01.03.2021 Project funding
127197 Subglacial Controls on the Short Term Dynamics at the Margin of the Greenland Ice Sheet 01.02.2010 Project funding

Abstract

Jakobshavn Isbrae is the fastest of three large outlet glaciers known to be thinning rapidly in Greenland. Jakobshavn Isbrae underwent dramatic changes in the last 10 years. Coinciding with surface drawdown was the retreat of the calving front by 10 km, and a doubling of flow speed to approx. 14 km/year.

We will extract a detailed quantitative flow history of this system from the GPS measurements, satellite imagery, and aerial photography, spanning 20 years. These measurements will be interpreted through finite element modeling efforts designed to address the three dimensional nature of the ice flow in this system, requiring a full solution of the mass, momentum and energy balance equations.

We will determine the role of ice dynamics in the thinning seen in this system, and therefore bracket the contributions of surface mass balance and basal melting; we will quantify the flow resistance provided by the rapidly disappearing floating tongue in this system, thus addressing connections to possible ocean forcing; and we will measure the ongoing changes in the velocity field in detail, so that modeling may more effectively limit the possible directions of the future evolution of this system. In addressing all of these goals with a coordinated field, remote sensing, and modeling effort, we will make progress toward the goal of understanding changes in the mass of the Earth's ice cover and the potential impact of those changes on sea level and society.

[The project is conducted in close collaboration with NASA-funded project with the same title.]
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