45893
2016
2016
eng
71
+
5
6
article
Nature Publ. Group
London
1
--
--
--
Linear sea-level response to abrupt ocean warming of major West Antarctic ice basin
Antarctica’s contribution to global sea-level rise has recently been increasing1. Whether its ice discharge will become unstable and decouple from anthropogenic forcing2,3,4 or increase linearly with the warming of the surrounding ocean is of fundamental importance5. Under unabated greenhouse-gas emissions, ocean models indicate an abrupt intrusion of warm circumpolar deep water into the cavity below West Antarctica’s Filchner–Ronne ice shelf within the next two centuries6,7. The ice basin’s retrograde bed slope would allow for an unstable ice-sheet retreat8, but the buttressing of the large ice shelf and the narrow glacier troughs tend to inhibit such instability9,10,11. It is unclear whether future ice loss will be dominated by ice instability or anthropogenic forcing. Here we show in regional and continental-scale ice-sheet simulations, which are capable of resolving unstable grounding-line retreat, that the sea-level response of the Filchner–Ronne ice basin is not dominated by ice instability and follows the strength of the forcing quasi-linearly. We find that the ice loss reduces after each pulse of projected warm water intrusion. The long-term sea-level contribution is approximately proportional to the total shelf-ice melt. Although the local instabilities might dominate the ice loss for weak oceanic warming12, we find that the upper limit of ice discharge from the region is determined by the forcing and not by the marine ice-sheet instability.
Nature climate change
10.1038/NCLIMATE2808
1758-678X
1758-6798
wos2016:2019
WOS:000367030800025
Levermann, A (reprint author), Potsdam Inst Climate Impact Res, D-14473 Potsdam, Germany., anders.levermann@pik-potsdam.de
Deutsche Forschungsgemeinschaft (DFG); German Federal Environmental Foundation (DBU); NASA [NNX13AM16G, NNX13AK27G]
importub
2020-03-22T22:20:01+00:00
filename=package.tar
0ba9d7848e5086e3697f02da0b8cd550
Matthias Mengel
Johannes Feldmann
Anders Levermann
Institut für Physik und Astronomie
Referiert
Import
41244
2016
2016
eng
1753
1769
17
564
postprint
1
2019-01-31
2019-01-31
--
Similitude of ice dynamics against scaling of geometry and physical parameters
The concept of similitude is commonly employed in the fields of fluid dynamics and engineering but rarely used in cryospheric research. Here we apply this method to the problem of ice flow to examine the dynamic similitude of isothermal ice sheets in shallow-shelf approximation against the scaling of their geometry and physical parameters. Carrying out a dimensional analysis of the stress balance we obtain dimensionless numbers that characterize the flow. Requiring that these numbers remain the same under scaling we obtain conditions that relate the geometric scaling factors, the parameters for the ice softness, surface mass balance and basal friction as well as the ice-sheet intrinsic response time to each other. We demonstrate that these scaling laws are the same for both the (two-dimensional) flow-line case and the three-dimensional case. The theoretically predicted ice-sheet scaling behavior agrees with results from numerical simulations that we conduct in flow-line and three-dimensional conceptual setups. We further investigate analytically the implications of geometric scaling of ice sheets for their response time. With this study we provide a framework which, under several assumptions, allows for a fundamental comparison of the ice-dynamic behavior across different scales. It proves to be useful in the design of conceptual numerical model setups and could also be helpful for designing laboratory glacier experiments. The concept might also be applied to real-world systems, e.g., to examine the response times of glaciers, ice streams or ice sheets to climatic perturbations.
Postprints der Universität Potsdam : Mathematisch Naturwissenschaftliche Reihe
10.25932/publishup-41244
urn:nbn:de:kobv:517-opus4-412441
1866-8372
online registration
The Cryosphere 10 (2016) 4, pp. 1753–1969 DOI 10.5194/tc-10-1753–2016
CC-BY - Namensnennung 4.0 International
Johannes Feldmann
Anders Levermann
Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
564
eng
uncontrolled
grounding line motion
eng
uncontrolled
full-stokes model
eng
uncontrolled
West Antarctica
eng
uncontrolled
sheet models
eng
uncontrolled
Pine Island
eng
uncontrolled
stream-B
eng
uncontrolled
shelf
eng
uncontrolled
flow
eng
uncontrolled
sensitivity
eng
uncontrolled
collapse
Geografie, Reisen
open_access
Mathematisch-Naturwissenschaftliche Fakultät
Referiert
Open Access
Copernicus
Universität Potsdam
https://publishup.uni-potsdam.de/files/41244/pmnr564.pdf
45054
2016
2016
eng
1753
1769
17
10
article
Copernicus
Göttingen
1
--
--
--
Similitude of ice dynamics against scaling of geometry and physical parameters
The concept of similitude is commonly employed in the fields of fluid dynamics and engineering but rarely used in cryospheric research. Here we apply this method to the problem of ice flow to examine the dynamic similitude of isothermal ice sheets in shallow-shelf approximation against the scaling of their geometry and physical parameters. Carrying out a dimensional analysis of the stress balance we obtain dimensionless numbers that characterize the flow. Requiring that these numbers remain the same under scaling we obtain conditions that relate the geometric scaling factors, the parameters for the ice softness, surface mass balance and basal friction as well as the ice-sheet intrinsic response time to each other. We demonstrate that these scaling laws are the same for both the (two-dimensional) flow-line case and the three-dimensional case. The theoretically predicted ice-sheet scaling behavior agrees with results from numerical simulations that we conduct in flow-line and three-dimensional conceptual setups. We further investigate analytically the implications of geometric scaling of ice sheets for their response time. With this study we provide a framework which, under several assumptions, allows for a fundamental comparison of the ice-dynamic behavior across different scales. It proves to be useful in the design of conceptual numerical model setups and could also be helpful for designing laboratory glacier experiments. The concept might also be applied to real-world systems, e.g., to examine the response times of glaciers, ice streams or ice sheets to climatic perturbations.
The Cryosphere : TC ; an interactive open access journal of the European Geosciences Union
10.5194/tc-10-1753-2016
1994-0416
1994-0424
wos2016:2019
WOS:000383798000001
Levermann, A (reprint author), Potsdam Inst Climate Impact Res PIK, Potsdam, Germany.; Levermann, A (reprint author), Univ Potsdam, Inst Phys, Potsdam, Germany.; Levermann, A (reprint author), Columbia Univ, LDEO, New York, NY 10025 USA., anders.levermann@pik-potsdam.de
Deutsche Forschungsgemeinschaft (DFG) [1158]
importub
2020-03-22T15:19:01+00:00
filename=package.tar
1b5f2d0444641c4cf715fa317714d9ef
Johannes Feldmann
Anders Levermann
Institut für Physik und Astronomie
Referiert
Import