Glacial isostatic adjustment in Fennoscandia—A review of data and modeling

Steffen, Holger; Wu, Patrick

doi:10.1016/j.jog.2011.03.002

Cited by 191 publications

(156 citation statements)

References 265 publications

(400 reference statements)

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“…The intent of the GIA modeling work performed here is, therefore, to find a land motion model that best fits the observed vertical velocities, rather than as an investigation of past ice mass changes and/or Earth viscosity structure. We note that other studies have inferred Earth viscosity values differing to ours and indicate significant lateral variations of Earth structure across Fennoscandia (see the in-depth review of Steffen and Wu (2011)). Indeed, lateral variations in Earth structure must be included if GNSS observations are to be interpreted correctly for studies of GIA (Whitehouse et al 2006), but this goes somewhat beyond the scope of our work here.…”

Section: Earth Model Sensitivity Test and Determining A Best-fit Modelcontrasting

confidence: 73%

Estimates of twenty-first century sea-level changes for Norway

2013

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In this work we establish a framework for estimating future regional sea-level changes for Norway. Following recently published works, we consider how different physical processes drive non-uniform sea-level changes by accounting for spatial variations in (1) ocean density and circulation (2) ice and ocean mass changes and associated gravitational effects on sea level and (3) vertical land motion arising from past surface loading change and associated gravitational effects on sea level. An important component of past and present sea-level change in Norway is glacial isostatic adjustment. Central to our study, therefore, is a reassessment of vertical land motion using a far larger set of new observations from a permanent GNSS network. Our twenty-first century sea-level estimates are split into two parts. Firstly, we show regional projections largely based on findings from the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC AR4) and dependent on the emission scenarios A2, A1B and B1. These indicate that twenty-first century relative sea-level changes in Norway will vary between -0.2 to 0.3 m (1-sigma ± 0.13 m). Secondly, we explore a high-end scenario, in which a global atmospheric temperature rise of up to 6°C and emerging collapse for some areas of the Antarctic ice sheets are assumed. Using this approach twenty-first century relative sea-level changes in Norway are found to vary between 0.25 and 0.85 m (min/ max ± 0.45 m). We attach no likelihood to any of our projections owing to the lack of understanding of some of the processes that cause sea-level change.

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Section: Earth Model Sensitivity Test and Determining A Best-fit Modelcontrasting

confidence: 73%

Estimates of twenty-first century sea-level changes for Norway

2013

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“…A range of global and regional studies indicate that the mean viscosity of the upper mantle lies in the range 10 20 -10 21 Pa s, while the viscosity of the lower mantle is less tightly constrained to lie in the range 10 21 -10 23 Pa s (e.g. Mitrovica, 1996;Lambeck et al, 1998;Milne et al, 470 2001;Peltier, 2004;Bradley et al, 2011;Steffen and Wu, 2011;Whitehouse et al, 2012b;Lambeck et al, 2014;Lecavalier et al, 2014;Peltier et al, 2015;Nakada et al, 2016). GIA modelling can be used to solve for the depth-dependent viscosity profile of the mantle, but it is important to assess the resolving power of the constraining data sets when considering the accuracy and uniqueness of the results (Mitrovica and Peltier, 1991a;Milne et al, 2004;Paulson et al, 2007b).…”

Section: Mantle Viscositymentioning

confidence: 99%

Glacial Isostatic Adjustment modelling: historical perspectives, recent advances, and future directions

Whitehouse¹

2018

Preprint

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Abstract. Glacial Isostatic Adjustment (GIA) describes the response of the solid Earth, the gravitational field, and 5 consequently the oceans to the growth and decay of the global ice sheets. It is a process that takes place relatively rapidly, triggering 100 m-scale changes in sea level and solid Earth deformation over just a few tens of thousands of years. Indeed, the first-order effects of GIA could already be quantified several hundred years ago without reliance on precise measurement techniques and scientists have been developing a unifying theory for the observations for over 200 years. Progress towards this goal required a number of significant breakthroughs to be made, including the recognition that ice sheets were once 10 more extensive, the solid Earth changes shape over time, and gravity plays a central role in determining the pattern of sealevel change. This article describes in detail the historical development of the field of GIA and an overview of the processes involved. Significant recent progress has been made as concepts associated with GIA have begun to be incorporated into parallel fields of research; these advances are discussed, along with the role that GIA is likely to play in addressing outstanding research questions within the field of Earth system modelling. 15

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“…However, the characteristic elliptic shape of GIA is not immediately visible in the static gravity field. Other sources contribute to the gravity field, such as density anomalies in the crust or mantle, crustal thickening, or even a long-wavelength feature related to the Icelandic mantle plume [Marquart, 1989;Steffen and Wu, 2011]. The question that arises is whether, given the contribution of all these sources, it is possible to extract information from static gravity field observations to constrain GIA modeling.…”

Section: Introductionmentioning

confidence: 99%

Glacial isostatic adjustment in the static gravity field of Fennoscandia

et al. 2015

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In the central part of Fennoscandia, the crust is currently rising, because of the delayed response of the viscous mantle to melting of the Late Pleistocene ice sheet. This process, called Glacial Isostatic Adjustment (GIA), causes a negative anomaly in the present-day static gravity field as isostatic equilibrium has not been reached yet. Several studies have tried to use this anomaly as a constraint on models of GIA, but the uncertainty in crustal and upper mantle structures has not been fully taken into account. Therefore, our aim is to revisit this using improved crustal models and compensation techniques. We find that in contrast with other studies, the effect of crustal anomalies on the gravity field cannot be effectively removed, because of uncertainties in the crustal and upper mantle density models. Our second aim is to estimate the effects on geophysical models, which assume isostatic equilibrium, after correcting the observed gravity field with numerical models for GIA. We show that correcting for GIA in geophysical modelling can give changes of several kilometer in the thickness of structural layers of modeled lithosphere, which is a small but significant correction. Correcting the gravity field for GIA prior to assuming isostatic equilibrium and inferring density anomalies might be relevant in other areas with ongoing postglacial rebound such as North America and the polar regions.

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Glacial isostatic adjustment in Fennoscandia—A review of data and modeling

Cited by 191 publications

References 265 publications

Estimates of twenty-first century sea-level changes for Norway

Estimates of twenty-first century sea-level changes for Norway

Glacial Isostatic Adjustment modelling: historical perspectives, recent advances, and future directions

Glacial isostatic adjustment in the static gravity field of Fennoscandia

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