The contribution of glacial isostatic adjustment to projections of sea‐level change along the Atlantic and Gulf coasts of North America

Love, Ryan; Milne, Glenn A.; Tarasov, Lev; Engelhart, Simon E.; Hijma, M.P.; Latychev, Konstantin; Horton, Benjamin P.; Törnqvist, Torbjörn E.

doi:10.1002/2016ef000363

Cited by 71 publications

(112 citation statements)

References 172 publications

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“…For the GIA model, the uncertainty is tightly constrained by the GPS observations and, as discussed, only accounts for changes in Earth model parameters. Better quantifying the GIA uncertainty is a challenging task but more rigorous methods are forthcoming (e.g., [57]). Finally, it is important to recognise that neither of these uncertainty estimates account for possible systematic errors in the reference frame.…”

Section: Comparison Of Gia Model and Least-squares Collocation Approachmentioning

confidence: 99%

Projected 21st Century Sea-Level Changes, Observed Sea Level Extremes, and Sea Level Allowances for Norway

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Ravndal

Sande

et al. 2017

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Changes to mean sea level and/or sea level extremes (e.g., storm surges) will lead to changes in coastal impacts. These changes represent a changing exposure or risk to our society. Here, we present 21st century sea-level projections for Norway largely based on the Fifth Assessment Report from the Intergovernmental Panel for Climate Change (IPCC AR5). An important component of past and present sea-level change in Norway is glacial isostatic adjustment. We therefore pay special attention to vertical land motion, which is constrained using new geodetic observations with improved spatial coverage and accuracies, and modelling work. Projected ensemble mean 21st century relative sea-level changes for Norway are, depending on location, from −0.10 to 0.30 m for emission scenario RCP2.6; 0.00 to 0.35 m for RCP 4.5; and 0.15 to 0.55 m for RCP8.5. For all RCPs, the projected ensemble mean indicates that the vast majority of the Norwegian coast will experience a rise in sea level. Norway's official return heights for extreme sea levels are estimated using the average conditional exceedance rate (ACER) method. We adapt an approach for calculating sea level allowances for use with the ACER method. All the allowances calculated give values above the projected ensemble mean Relative Sea Level (RSL) rise, i.e., to preserve the likelihood of flooding from extreme sea levels, a height increase above the most likely RSL rise should be used in planning. We also show that the likelihood of exceeding present-day return heights will dramatically increase with sea-level rise.

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Section: Comparison Of Gia Model and Least-squares Collocation Approachmentioning

confidence: 99%

Projected 21st Century Sea-Level Changes, Observed Sea Level Extremes, and Sea Level Allowances for Norway

Simpson

Ravndal

Sande

et al. 2017

JMSE

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“…Additionally, the MD is the depocenter of the Mississippi River drainage basin, the fourth largest drainage basin in the world. Regional sea level rise is distinct from global RSL rise as even in the absence of local subsidence sea level is typically not equal to global mean sea level (Love et al, 2016;Slangen et al, 2014). All of these processes need to be understood to make accurate projections of regional sea level for the MD and adjacent coastline.…”

Section: Introductionmentioning

confidence: 99%

“…Additionally, it is known that nonisostatic processes such as sediment compaction are a dominant contributor to subsidence and sea level rise in the MD, along with subsidence related to fluid extraction and faulting. A primary motivation for doing this is to make use of a recently compiled and quality-assessed RSL data base (Hijma et al, 2015;Love et al, 2016) for constraining model parameters. ) Extraction of groundwater led to subsidence rates in heavily developed areas, such as New Orleans, of tens of mm/yr (Jones et al, 2016), and extraction of hydrocarbons in Southern Louisiana and Texas led to subsidence rates of tens of mm/yr, 3 orders of magnitude higher than the "background" geologic subsidence rate (Morton et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

“…Sediment compaction can lead to rates of subsidence of up to 5 mm/yr on millennial timescales, and up to 10 mm/yr on decadal timescales (Törnqvist et al, 2008. An important quality of these data is that they are not significantly affected by compaction (Love et al, 2016) and so represent one of the few data sets in the region that can provide accurate constraints on vertical motion of the underlying consolidated strata. Wolstencroft et al (2014) modeled deformation and uplift rates in the MD and accounted for both GIA and deformation caused by sediment loading; they concluded that SIA alone could not account for the high rates of observed subsidence in the MD, with a maximum estimated rate of subsidence from SIA of about 0.5 mm/yr.…”

Section: Introductionmentioning

confidence: 99%

“…A recent study (Van der Wal & IJpelaar, 2017) applied the sea level theory of Dalca et al (2013) to examine the influence of glacially induced sediment redistribution to modeled observables in Fennoscandia for the last glacial cycle. A recent study considered RSL observations from the U.S. Gulf Coast to constrain GIA model parameters and place bounds on the contribution of this process to future RSL change (Love et al, 2016). One aim of this work is to quantify the influence of SIA on RSL in the MD region to determine if the application of RSL models that simulate SIA is necessary.…”

Section: Introductionmentioning

confidence: 99%

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The Influence of Sediment Isostatic Adjustment on Sea Level Change and Land Motion Along the U.S. Gulf Coast

et al. 2018

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Sea level rise presents a hazard for coastal populations, and the Mississippi Delta (MD) is a region particularly at risk due to the high rates of land subsidence. We apply a gravitationally self‐consistent model of glacial and sediment isostatic adjustment (SIA) along with a realistic sediment load reconstruction in this region for the first time to determine isostatic contributions to relative sea level (RSL) and land motion. We determine optimal model parameters (Earth rheology and ice history) using a new high‐quality compaction‐free sea level indicator database. Using the optimal model parameters, we show that SIA can lower predicted RSL in the MD area by several meters over the Holocene and so should be taken into account when modeling these data. We compare modeled contemporary rates of vertical land motion with those inferred using GPS. This comparison indicates that isostatic processes can explain the majority of the observed vertical land motion north of latitude 30.7°N, where subsidence rates average about 1 mm/yr; however, subsidence south of this latitude shows large data‐model discrepancies of greater than 3 mm/yr, indicating the importance of nonisostatic processes. This discrepancy extends to contemporary RSL change, where we find that the SIA contribution in the Delta is on the order of 10−1 mm/yr. We provide estimates of the isostatic contributions to 20th and 21st century sea level rates at Gulf Coast Permanent Service for Mean Sea Level tide gauge locations as well as vertical and horizontal land motion at GPS station locations near the MD.

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21st Century Sea‐Level Rise in Line with the Paris Accord

2018

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As global average sea‐level rises in the early part of this century there is great interest in how much global and local sea level will change in the forthcoming decades. The Paris Climate Agreement's proposed temperature thresholds of 1.5°C and 2°C have directed the research community to ask what differences occur in the climate system for these two states. We have developed a novel approach to combine climate model outputs that follow specific temperature pathways to make probabilistic projections of sea‐level in a 1.5°C and 2°C world. We find median global sea‐level (GSL) projections for 1.5°C and 2°C temperature pathways of 44 and 50 cm, respectively. The 90% uncertainty ranges (5%–95%) are both around 48 cm by 2100. In addition, we take an alternative approach to estimate the contribution from ice sheets by using a semi‐empirical GSL model. Here we find median projections of 58 and 68 cm for 1.5°C and 2°C temperature pathways. The 90% uncertainty ranges are 67 and 82 cm respectively. Regional projections show similar patterns for both temperature pathways, though differences vary between the median projections (2–10 cm) and 95th percentile (5–20 cm) for the bulk of oceans using process‐based approach and 10–15 cm (median) and 15–25 cm (95th percentile) using the semi‐empirical approach. Plain Language Summary The sea level you experience at the coast can be estimated by the sum of contributions from ocean expansion, currents, ice melt from glaciers and ice sheets, land‐water extraction/damming, and land motion. How sea level changes depends strongly on where you are because each contribution has a unique pattern. We use knowledge of these changes to make projections about future sea‐level rise. We estimate how much sea‐level could change if societies achieve either of the Paris Climate Agreement's temperature targets by 2100. If we reach 1.5°C or 2.0°C by 2100, GSL should rise around 44–50 cm, respectively. Using a slightly different method we find the global rise could be 58–68 cm. An incomplete picture of the sea‐level components means that estimates could be out by up to 80 cm, though all projections show a sea‐level rise of at least 20 cm.

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The contribution of glacial isostatic adjustment to projections of sea‐level change along the Atlantic and Gulf coasts of North America

Cited by 71 publications

References 172 publications

Projected 21st Century Sea-Level Changes, Observed Sea Level Extremes, and Sea Level Allowances for Norway

Projected 21st Century Sea-Level Changes, Observed Sea Level Extremes, and Sea Level Allowances for Norway

The Influence of Sediment Isostatic Adjustment on Sea Level Change and Land Motion Along the U.S. Gulf Coast

21st Century Sea‐Level Rise in Line with the Paris Accord

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