scholarly journals An Ancient Meltwater Pulse Raised Sea Levels by 18 Meters

Eos ◽  
2021 ◽  
Vol 102 ◽  
Author(s):  
Tim Hornyak

Meltwater pulse 1A, a period of rapid sea level rise after the last deglaciation, was powered by melting ice from North America and Scandinavia, according to new research.

1969 ◽  
Vol 28 ◽  
pp. 21-24 ◽  
Author(s):  
Carina Bendixen ◽  
Jørn Bo Jensen ◽  
Ole Bennike ◽  
Lars Ole Boldreel

The Kattegat region is located in the wrench zone between the Fennoscandian shield and the Danish Basin that has repeatedly been tectonically active. The latest ice advances during the Quaternary in the southern part of Kattegat were from the north-east, east and south-east (Larsen et al. 2009). The last deglaciation took place at c. 18 to 17 ka BP (Lagerlund & Houmark-Nielsen 1993; Houmark-Nielsen et al. 2012) and was followed by inundation of the sea that formed a palaeo-Kattegat (Conradsen 1995) with a sea level that was relatively high because of glacio-isostatic depression. Around 17 ka BP, the ice margin retreated to the Øresund region and meltwater from the retreating ice drained into Kattegat. Over the next millennia, the region was characterised by regression because the isostatic rebound of the crust surpassed the ongoing eustatic sea-level rise, and a regional lowstand followed at the late glacial to Holocene transition (Mörner 1969; Thiede 1987; Lagerlund & Houmark-Nielsen 1993; Jensen et al. 2002a, b).


2020 ◽  
Vol 50 (12) ◽  
pp. 3623-3639
Author(s):  
Geoffrey Gebbie

AbstractSea level rise over the last deglaciation is dominated by the mass of freshwater added to the oceans by the melting of the great ice sheets. While the steric effect of changing seawater density is secondary over the last 20 000 years, processes connected to deglacial warming, the redistribution of salt, and the pressure load of meltwater all influence sea level rise by more than a meter. Here we develop a diagnostic for steric effects that is valid when oceanic mass is changing. This diagnostic accounts for seawater compression due to the added overlying pressure of glacial meltwater, which is here defined to be a barosteric effect. Analysis of three-dimensional global seawater reconstructions of the last deglaciation indicates that thermosteric height change (1.0–1.5 m) is counteracted by barosteric (−1.9 m) and halosteric (from −0.4 to 0.0 m) effects. The total deglacial steric effect from −0.7 to −1.1 m has the opposite sign of analyses that assume that thermosteric expansion is dominant. Despite the vertical oceanic structure not being well constrained during the Last Glacial Maximum, net seawater contraction appears robust as it occurs in four reconstructions that were produced using different paleoceanographic datasets. Calculations that do not account for changes in ocean pressure give the misleading impression that steric effects enhanced deglacial sea level rise.


Author(s):  
Jessica Kelln ◽  
Sönke Dangendorf ◽  
Jürgen Jensen ◽  
Justus Patzke ◽  
Wolfgang Niemeier ◽  
...  

Global mean sea level has risen over the 20th century (Hay et al. 2015; Dangendorf et al. 2017) and under sustained greenhouse gas emissions it is projected to further accelerate throughout the 21st century (Church et al. 2013) with large spatial variations, significantly threatening coastal communities. Locally the effects of geocentric (sometimes also referred to absolute) sea level rise can further be amplified by vertical land motion (VLM) due to natural adjustments of the solid earth to the melting of the large ice-sheets during the last deglaciation (GIA) or local anthropogenic interventions such as groundwater or gas withdrawal (e.g. Santamaría-Gómez et al. 2017). Both, the observed and projected geocentric sea level rise as well as VLM are critically important for coastal planning and engineering, since only their combined effect determines the total threat of coastal flooding at specific locations. Furthermore, due large spatial variability of sea level, information is required not only at isolated tide gauge (TG) locations but also along the coastline stretches in between.


2021 ◽  
Author(s):  
Fiona D. Hibbert ◽  
Felicity Williams ◽  
Eelco Rohling

<p>Geologically recorded sea-level variations represent the sum total of all contributing processes, be it known or unknown, and may thus help in finding the full range of future sea-level rise. Significant sea-level-rise contributions from both northern and southern ice sheets are not unprecedented in the geological record and offer a well-constrained range of natural scenarios from intervals during which ice volumes were similar to or smaller than present (i.e., interglacial periods), to intervals during which total ice volume was greater (i.e., glacial periods).</p><p>The last deglaciation is the most recent period of widespread destabilisation and collapse of major continental ice sheets. Records spanning the last deglaciation (as well as the ice volume maxima) are few, fragmentary and seemingly inconsistent (e.g., the timing and magnitude of melt-water pulses), in part due to locational (tectonic and glacio-isostatic) as well as modern analogue considerations (e.g., palaeo-water depth or facies formation depth). We present a new synthesis of sea-level indicators, with particular emphasis on the geological and biological context, as well as the uncertainties of each record. Using this new compilation and the novel application of statistical methods (trans-dimensional change-point analysis, which avoids “overfitting” of noise in the data), we will assess global ice-volume changes, sea-level fluctuations and changes in climate during the last deglaciation. Finally, we discuss the implications of these uncertainties on our ability to constrain past cryosphere changes.</p>


2017 ◽  
Vol 8 (1) ◽  
Author(s):  
Pankaj Khanna ◽  
André W. Droxler ◽  
Jeffrey A. Nittrouer ◽  
John W. Tunnell Jr ◽  
Thomas C. Shirley

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