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Timescales of glacial isostatic adjustment in Greenland: is transient rheology required?

Pan, Linda; Mitrovica, Jerry X; Milne, Glenn A; Hoggard, Mark J; Woodroffe, Sarah A

Timescales of glacial isostatic adjustment in Greenland: is transient rheology required? Thumbnail


Linda Pan

Jerry X Mitrovica

Glenn A Milne

Mark J Hoggard


The possibility of a transient rheological response to ice age loading, first discussed in the literature of the 1980s, has received renewed attention. Transient behaviour across centennial to millennial timescales has been invoked to reconcile apparently contradictory inferences of steady-state (Maxwell) viscosity based on two distinct data sets from Greenland: Holocene sea-level curves and Global Navigation Satellite System (GNSS) derived modern crustal uplift data. To revisit this issue, we first compute depth-dependent Fréchet kernels using 1-D Maxwell viscoelastic Earth models and demonstrate that the mantle resolving power of the two Greenland data sets is highly distinct, reflecting the differing spatial scale of the associated surface loading: the sea-level records are sensitive to viscosity structure across the entire upper mantle while uplift rates associated with post-1000 CE fluctuations of the Greenland Ice Sheet have a dominant sensitivity to shallow asthenosphere viscosity. Guided by these results, we present forward models which demonstrate that a moderate low viscosity zone beneath the lithosphere in Maxwell Earth models provides a simple route to simultaneously reconciling both data sets by significantly increasing predictions of present-day uplift rates in Greenland whilst having negligible impact on predictions of Holocene relative sea-level curves from the region. Our analysis does not rule out the possibility of transient deformation, but it suggests that it is not required to simultaneously explain these two data sets. A definitive demonstration of transient behaviour requires that one account for the resolving power of the data sets in modelling the glacial isostatic adjustment process.


Pan, L., Mitrovica, J. X., Milne, G. A., Hoggard, M. J., & Woodroffe, S. A. (2024). Timescales of glacial isostatic adjustment in Greenland: is transient rheology required?. Geophysical Journal International, 237(2), 989-995.

Journal Article Type Article
Acceptance Date Mar 6, 2024
Online Publication Date Mar 11, 2024
Publication Date Mar 7, 2024
Deposit Date May 8, 2024
Publicly Available Date May 8, 2024
Journal Geophysical Journal International
Print ISSN 0956-540X
Electronic ISSN 1365-246X
Publisher Oxford University Press
Peer Reviewed Peer Reviewed
Volume 237
Issue 2
Pages 989-995
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Copyright Statement
Published by Oxford University Press on behalf of The Royal Astronomical Society. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.

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