Space-geodetic and water level gauge constraints on continental uplift and tilting over North America: regional convergence of the ICE-6G_C (VM5a/VM6) models

Roy, Keven; Peltier, W. R.

doi:10.1093/gji/ggx156

Cited by 69 publications

(97 citation statements)

References 65 publications

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“…A host of improvements in global GIA models have evolved over the past decades. New models (including the ICE‐6G model, Peltier et al, ; Purcell et al,; Roy & Peltier, , and the latest version of the Australian National University (ANU) model, Lambeck et al, , ) use considerably more data that constrain moraine position and dating during the ice sheet collapse phase (e.g., Gowan et al, ; Simon et al, ; Tarasov et al, ). Space geodesy has a growing role (Milne et al, ), along with an ever greater volume of relative sea level (RSL) data (Murray‐Wallace & Woodroffe, ).…”

Section: Introductionmentioning

confidence: 99%

GIA Model Statistics for GRACE Hydrology, Cryosphere, and Ocean Science

Caron

Ivins

Larour

et al. 2018

Geophysical Research Letters

190

366

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We provide a new analysis of glacial isostatic adjustment (GIA) with the goal of assembling the model uncertainty statistics required for rigorously extracting trends in surface mass from the Gravity Recovery and Climate Experiment (GRACE) mission. Such statistics are essential for deciphering sea level, ocean mass, and hydrological changes because the latter signals can be relatively small (≤2 mm/yr water height equivalent) over very large regions, such as major ocean basins and watersheds. With abundant new >7 year continuous measurements of vertical land motion (VLM) reported by Global Positioning System stations on bedrock and new relative sea level records, our new statistical evaluation of GIA uncertainties incorporates Bayesian methodologies. A unique aspect of the method is that both the ice history and 1‐D Earth structure vary through a total of 128,000 forward models. We find that best fit models poorly capture the statistical inferences needed to correctly invert for lower mantle viscosity and that GIA uncertainty exceeds the uncertainty ascribed to trends from 14 years of GRACE data in polar regions.

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Section: Introductionmentioning

confidence: 99%

GIA Model Statistics for GRACE Hydrology, Cryosphere, and Ocean Science

Caron

Ivins

Larour

et al. 2018

Geophysical Research Letters

190

366

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“…While our results herein and in SP establish the ice dynamical consistency of the present version of I6G, this clearly does not preclude the consistency of alternative scenarios that refine I6G (e.g., by incorporating Laurentide and Fennoscandian contributions to MWP1b). Refinements along these lines have already been described by Roy and Peltier (, ), and each new “canonical” ICE‐ x G reconstruction can, naturally, become a new basis for further studies of ice dynamical smoothing. Roy and Peltier (, ) considered adjustments that either uniformly or nonuniformly modulated the time dependence of North American ice thickness over the interval of interest, and examination of the spatial structure of ice core climate adjustments, δ I (Figure ), suggests that MWP1b ice losses would more likely have been concentrated in southern, warm climate regions.…”

Section: Discussionmentioning

confidence: 82%

“…Refinements along these lines have already been described by Roy and Peltier (, ), and each new “canonical” ICE‐ x G reconstruction can, naturally, become a new basis for further studies of ice dynamical smoothing. Roy and Peltier (, ) considered adjustments that either uniformly or nonuniformly modulated the time dependence of North American ice thickness over the interval of interest, and examination of the spatial structure of ice core climate adjustments, δ I (Figure ), suggests that MWP1b ice losses would more likely have been concentrated in southern, warm climate regions. Weakly nudged results with τ f =1,000 years predict ice core climate adjustments of the appropriate amplitude, but the aforementioned observational inconsistencies in these results suggest a breakdown of the perturbative approach described herein.…”

Section: Discussionmentioning

confidence: 82%

“…The ice core climate adjustments computed in the results section 4 will be shown to challenge recent hypotheses ascribing the geographical origins of Meltwater Pulse 1B (MWP1b) to a sudden grounding line retreat beneath the regions occupied by the present‐day Antarctic ice shelves (Argus et al, ; Golledge et al, ; Peltier et al, ). The need for such a reassessment of this characteristic of I6G has recently been suggested by a growing body of evidence (Abdul et al, ; Bard et al, ; Mortlock et al, ) and by further work on the pure GIA‐based reconstruction methodology (Roy & Peltier, , ). Our new results (section 4) will show, for the most reasonable nudging time scales, τ f , that ice dynamical “nudging” toward I6G triggers abrupt, climate‐induced Laurentide and Fennoscandian deglaciation events around the time of MWP1b even though these events do not exist in the original I6G reconstructions of these ice sheets.…”

Section: Introductionmentioning

confidence: 99%

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Assimilating the ICE‐6G_C Reconstruction of the Latest Quaternary Ice Age Cycle Into Numerical Simulations of the Laurentide and Fennoscandian Ice Sheets

Stuhne

Peltier

2017

JGR Earth Surface

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We analyze the effects of nudging 100 kyr numerical simulations of the Laurentide and Fennoscandian ice sheets toward the glacial isostatic adjustment‐based (GIA‐based) ICE‐6G_C reconstruction of the most recent ice age cycle. Starting with the ice physics approximations of the PISM ice sheet model and the SeaRISE simulation protocols, we incorporate nudging at characteristic time scales, τf, through anomalous mass balance terms in the ice mass conservation equation. As should be expected, these mass balances exhibit physically unrealistic details arising from pure GIA‐based reconstruction geometry when nudging is very strong (τf=20 years for North America), while weakly nudged (τf=1,000 years) solutions deviate from ICE‐6G_C sufficiently to degrade its observational fit quality. For reasonable intermediate time scales (τf=100 years and 200 years), we perturbatively analyze nudged ice dynamics as a superposition of “leading‐order smoothing” that diffuses ICE‐6G_C in a physically and observationally consistent manner and “higher‐order” deviations arising, for instance, from biases in the time dependence of surface climate boundary conditions. Based upon the relative deviations between respective nudged simulations in which these biases follow surface temperature from ice cores and eustatic sea level from marine sediment cores, we compute “ice core climate adjustments” that suggest how local paleoclimate observations may be applied to the systematic refinement of ICE‐6G_C. Our results are consistent with a growing body of evidence suggesting that the geographical origins of Meltwater Pulse 1B (MWP1b) may lie primarily in North America as opposed to Antarctica (as reconstructed in ICE‐6G_C).

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“…We compare our data to the predictions of the recent ICE-5G and ICE-6G models (Peltier, 2004;Peltier et al, 2015), and also to models we compute for a range of viscosity structures using the older ICE-3G model. Because our study area is distal to the main ice sheets and has consistently remained ice free, the predicted present-day vertical motions are small and are relatively insensitive to details regarding the ice history and geometry (e.g., Love et al, 2016 ;Roy & Peltier, 2015, 2017Sato et al, 2011Sato et al, , 2012Yousefi et al, 2018). Using a wide range of input model Alaska uplift is due to subduction that is compounded by isostatic rebound from glacial ice loss.…”

Section: Gia Modelsmentioning

confidence: 99%

Vertical Velocities, Glacial Isostatic Adjustment, and Earth Structure of Northern and Western Alaska Based on Repeat GPS Measurements

DeGrandpre

Freymueller

2019

JGR Solid Earth

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Glacial isostatic adjustment (GIA), resulting from the Pleistocene loading of the Laurentide and Cordilleran ice sheets, is frequently associated with positive vertical velocities, or uplift. In Northern and Western Alaska, thousands of kilometers from the center of these ice sheets, vertical motion is primarily negative, or subsidence. Previously, no regional Earth structure model has been estimated for these areas using GIA modeling techniques, and the contribution of GIA processes to the observed subsidence signal has not been studied. We compare the vertical motion rates from 54 campaign and continuous GPS sites in Northern and Western Alaska to the predictions of the ICE‐5G and ICE‐6G GIA models, and to a suite of models that vary with four adjustable parameters defining the lithospheric thickness, asthenospheric thickness and viscosity, and upper mantle thickness and viscosity with the ICE‐3G loading model of Tushingham and Peltier (1991, https://doi.org/10.1029/90JB01583). The best overall fit with the ICE‐3G loading model and Earth model parameters were 120‐km lithosphere over a 100‐km asthenosphere with a viscosity of 2.5 × 1019 Pa/s, overlying a 450‐km‐thick upper mantle with a viscosity of 1.5 × 1021 Pa/s. These values are for a fixed lower mantle viscosity of 3 × 1021 Pa/s in a one‐dimensional Earth model that uses a linear Maxwell rheology. The GIA estimates are found to fit the GPS observations well and can be used to more accurately interpolate between measurement sites in a region where there is sparse spatial and temporal coverage of tectonic vertical velocities.

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Space-geodetic and water level gauge constraints on continental uplift and tilting over North America: regional convergence of the ICE-6G_C (VM5a/VM6) models

Cited by 69 publications

References 65 publications

GIA Model Statistics for GRACE Hydrology, Cryosphere, and Ocean Science

GIA Model Statistics for GRACE Hydrology, Cryosphere, and Ocean Science

Assimilating the ICE‐6G_C Reconstruction of the Latest Quaternary Ice Age Cycle Into Numerical Simulations of the Laurentide and Fennoscandian Ice Sheets

Vertical Velocities, Glacial Isostatic Adjustment, and Earth Structure of Northern and Western Alaska Based on Repeat GPS Measurements

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