scholarly journals A Probabilistic Model of Coastal Bluff-Top Erosion in High Latitudes Due to Thermoabrasion: A Case Study from Baydaratskaya Bay in the Kara Sea

2020 ◽  
Vol 8 (3) ◽  
pp. 169
Author(s):  
Mohammad Akhsanul Islam ◽  
Raed Lubbad ◽  
Mohammad Saud Afzal
Keyword(s):  
Sea Level ◽  
Probabilistic Model ◽  
Coastal Erosion ◽  
Global Climate ◽  
High Sensitivity ◽  
Kara Sea ◽  
The Arctic ◽  
Field Observations ◽  
Sea Level Changes ◽  
Erosion Mechanisms

Arctic coastal erosion demands more attention as the global climate continues to change. Unlike those along low-latitude and mid-latitude, sediments along Arctic coastlines are often frozen, even during summer. Thermal and mechanical factors must be considered together when analysing Arctic coastal erosion. Two major erosion mechanisms in the Arctic have been identified: thermodenudation and thermoabrasion. Field observations of Arctic coastal erosion are available in Baydaratskaya Bay in the Kara Sea. The objective of this study is to develop a probabilistic model of thermoabrasion to simulate the measured coastal erosion at two sites where observations suggest thermoabrasion is dominant. The model simulates two time periods: (a) the summer of 2013 (2012–2013) and (b) the summer of 2017 (2016–2017). A probabilistic analysis is performed to quantify the uncertainties in the model results. The input parameters are assumed to follow normal and lognormal distributions with a 10% coefficient of variation. Monte Carlo simulation is applied to determine the erosion rates for the two different cases. The simulation results agree reasonably well with the field observations. In addition, a sensitivity analysis is performed, revealing a very high sensitivity of the model to sea-level changes. The model indicates that the relation between sea-level rise and thermoabrasional erosion is exponential.

scholarly journals On the geophysical processes impacting palaeo-sea-level observations

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Yusuke Yokoyama ◽  
Anthony Purcell
Keyword(s):  
Sea Level ◽  
Large Scale ◽  
Global Climate ◽  
Sea Level Change ◽  
Sea Level Changes ◽  
Factors Affecting ◽  
Ice Volume ◽  
Level Change ◽  
Recent Developments ◽  
Geophysical Processes

AbstractPast sea-level change represents the large-scale state of global climate, reflecting the waxing and waning of global ice sheets and the corresponding effect on ocean volume. Recent developments in sampling and analytical methods enable us to more precisely reconstruct past sea-level changes using geological indicators dated by radiometric methods. However, ice-volume changes alone cannot wholly account for these observations of local, relative sea-level change because of various geophysical factors including glacio-hydro-isostatic adjustments (GIA). The mechanisms behind GIA cannot be ignored when reconstructing global ice volume, yet they remain poorly understood within the general sea-level community. In this paper, various geophysical factors affecting sea-level observations are discussed and the details and impacts of these processes on estimates of past ice volumes are introduced.

Rising Seas and Retreating Coasts: Implications for the Arctic

2020 ◽  
Vol 35 (3) ◽  
pp. 468-497
Author(s):  
Clive Schofield ◽  
Suzanne Lalonde
Keyword(s):  
Climate Change ◽  
Sea Level ◽  
Coastal Erosion ◽  
Legal Issues ◽  
The Arctic ◽  
Future Challenge ◽  
Legal Regime ◽  
Legal Responses ◽  
Key Aspects ◽  
Impacts Of Climate Change

Abstract This article addresses both the physical impacts and international legal issues arising from two interlinked stressors on Arctic coastlines: sea level rise and coastal erosion. Key aspects of the legal regime governing the baselines from which coastal States calculate the outer limits of their maritime zones are reviewed and a synopsis of the practice among the Arctic littoral States is provided. The article then turns to a discussion of the practical and international legal responses available to deal with the present and future challenge of rising seas and retreating coasts. The concluding section offers with some reflections on the way forward for a region experiencing some of the most devastating impacts of climate change.

Global Climate Model Performance over Alaska and Greenland

2008 ◽  
Vol 21 (23) ◽  
pp. 6156-6174 ◽  
Author(s):  
John E. Walsh ◽  
William L. Chapman ◽  
Vladimir Romanovsky ◽  
Jens H. Christensen ◽  
Martin Stendel
Keyword(s):  
Sea Level ◽  
Root Mean Square ◽  
Global Climate ◽  
Systematic Errors ◽  
The Arctic ◽  
Future Climate Change ◽  
Mean Square ◽  
Sea Level Pressure ◽  
Level Pressure ◽  
Mean Square Errors

Abstract The performance of a set of 15 global climate models used in the Coupled Model Intercomparison Project is evaluated for Alaska and Greenland, and compared with the performance over broader pan-Arctic and Northern Hemisphere extratropical domains. Root-mean-square errors relative to the 1958–2000 climatology of the 40-yr ECMWF Re-Analysis (ERA-40) are summed over the seasonal cycles of three variables: surface air temperature, precipitation, and sea level pressure. The specific models that perform best over the larger domains tend to be the ones that perform best over Alaska and Greenland. The rankings of the models are largely unchanged when the bias of each model’s climatological annual mean is removed prior to the error calculation for the individual models. The annual mean biases typically account for about half of the models’ root-mean-square errors. However, the root-mean-square errors of the models are generally much larger than the biases of the composite output, indicating that the systematic errors differ considerably among the models. There is a tendency for the models with smaller errors to simulate a larger greenhouse warming over the Arctic, as well as larger increases of Arctic precipitation and decreases of Arctic sea level pressure, when greenhouse gas concentrations are increased. Because several models have substantially smaller systematic errors than the other models, the differences in greenhouse projections imply that the choice of a subset of models may offer a viable approach to narrowing the uncertainty and obtaining more robust estimates of future climate change in regions such as Alaska, Greenland, and the broader Arctic.

scholarly journals <i>Lingulodinium machaerophorum</i> expansion over the last centuries in the Caspian Sea reflects global warming

2012 ◽  
Vol 9 (11) ◽  
pp. 16663-16704
Author(s):  
S. A. G. Leroy ◽  
H. A. K. Lahijani ◽  
J.-L. Reyss ◽  
F. Chalié ◽  
S. Haghani ◽  
...  
Keyword(s):  
Sea Level ◽  
Caspian Sea ◽  
Global Climate ◽  
Sediment Cores ◽  
Sea Surface ◽  
Sea Level Changes ◽  
The Caspian Sea ◽  
Sea Level Fluctuations ◽  
Marine Surface ◽  
A Minor

Abstract. We analysed dinoflagellate cyst assemblages in four short sediment cores, two of them dated by radionuclides, taken in the south basin of the Caspian Sea. The interpretation of the four sequences is supported by a collection of 27 lagoonal or marine surface sediment samples. A sharp increase in the biomass of the dinocyst occurs after 1967, especially owing to Lingulodinium machaerophorum. Considering nine other cores covering parts or the whole of Holocene, this species started to develop in the Caspian Sea only during the last three millennia. By analysing instrumental data and collating existing reconstructions of sea level changes over the last few millennia, we show that the main forcing of the increase of L. machaerophorum percentages and of the recent dinocyst abundance is global climate change, especially sea surface temperature increase. Sea level fluctuations likely have a minor impact. We argue that the Caspian Sea has entered the Anthropocene.

ISMIP6-based projections of ocean-forced Antarctic ice loss using the Community Ice Sheet Model 

2021 ◽  
Author(s):  
William Lipscomb ◽  
Gunter Leguy ◽  
Nicolas Jourdain ◽  
Xylar Asay-Davis ◽  
Hélène Seroussi ◽  
...  
Keyword(s):  
Sea Level ◽  
Climate Models ◽  
Global Climate ◽  
Ice Sheet ◽  
High Sensitivity ◽  
Global Climate Models ◽  
Thermal Forcing ◽  
Antarctic Ice Sheet ◽  
Basal Friction ◽  
West Antarctic

&lt;p&gt;The future retreat rate for marine-based regions of the Antarctic Ice Sheet is one of the largest uncertainties in sea-level projections. The Ice Sheet Model Intercomparison Project for CMIP6 (ISMIP6) aims to improve projections and quantify uncertainties by running an ensemble of ice sheet models with forcing derived from global climate models. Here, the Community Ice Sheet Model (CISM) is used to run ISMIP6-based projections of ocean-forced Antarctic Ice Sheet evolution. Using several combinations of sub-ice-shelf melt schemes, CISM is spun up to steady state over many millennia. During the spin-up, basal-friction and thermal-forcing parameters are adjusted to optimize agreement with the observed ice thickness. The model is then run forward to year 2500, applying ocean thermal forcing anomalies from six climate models. In all simulations, ocean warming triggers long-term retreat of the West Antarctic Ice Sheet, especially in the Filchner-Ronne and Ross sectors. The ocean-forced sea-level rise in 2500 varies from about 150 mm to 1300 mm, depending on the melt scheme and ocean forcing applied. Further experiments show relatively high sensitivity to the basal friction law, and moderate sensitivity to grid resolution and the prescribed collapse of small ice shelves. The Amundsen sector exhibits threshold behavior, with modest retreat under many parameter settings, but complete collapse under some combinations of low basal friction and high thermal-forcing anomalies. Large uncertainties remain, as a result of parameterized sub-shelf melt rates, simplified treatments of calving and basal friction, and the lack of ice&amp;#8211;ocean coupling.&lt;/p&gt;

Causes and consequences of Southern Ocean change: the IPCC SROCC assessment

2020 ◽  
Author(s):  
Michael Meredith ◽  
Martin Sommerkorn ◽  
Sandra Cassotta ◽  
Chris Derksen ◽  
Alexey Ekaykin ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Sea Ice ◽  
Sea Level ◽  
Ocean Circulation ◽  
Global Climate ◽  
Ice Sheets ◽  
The Arctic ◽  
Polar Regions ◽  
Ice Shelves

&lt;p&gt;Climate change in the polar regions exerts a profound influence both locally and over all of our planet.&amp;#160; Physical and ecosystem changes influence societies and economies, via factors that include food provision, transport and access to non-renewable resources.&amp;#160; Sea level, global climate and potentially mid-latitude weather are influenced by the changing polar regions, through coupled feedback processes, sea ice changes and the melting of snow and land-based ice sheets and glaciers.&lt;/p&gt;&lt;p&gt;Reflecting this importance, the IPCC Special Report on the Ocean and Cryosphere in a Changing Climate (SROCC) features a chapter highlighting past, ongoing and future change in the polar regions, the impacts of these changes, and the possible options for response.&amp;#160; The role of the polar oceans, both in determining the changes and impacts in the polar regions and in structuring the global influence, is an important component of this chapter.&lt;/p&gt;&lt;p&gt;With emphasis on the Southern Ocean and through comparison with the Arctic, this talk will outline key findings from the polar regions chapter of SROCC. It will synthesise the latest information on the rates, patterns and causes of changes in sea ice, ocean circulation and properties. It will assess cryospheric driving of ocean change from ice sheets, ice shelves and glaciers, and the role of the oceans in determining the past and future evolutions of polar land-based ice. The implications of these changes for climate, ecosystems, sea level and the global system will be outlined.&lt;/p&gt;

scholarly journals Coastal dynamics and submarine permafrost in shallow water of the central Laptev Sea, East Siberia

2015 ◽  
Vol 9 (4) ◽  
pp. 3741-3775 ◽  
Author(s):  
P. Overduin ◽  
S. Wetterich ◽  
F. Günther ◽  
M. N. Grigoriev ◽  
G. Grosse ◽  
...  
Keyword(s):  
Sea Level ◽  
Coastal Erosion ◽  
Solute Concentration ◽  
The Arctic ◽  
Laptev Sea ◽  
East Siberia ◽  
Concentration Gradients ◽  
Degradation Rates ◽  
A Site

Abstract. Coastal erosion and relative sea-level rise transform terrestrial landscapes into marine environments. In the Arctic, these processes inundate terrestrial permafrost with seawater and create submarine permafrost. Permafrost begins to warm under marine conditions, which can destabilize the sea floor and may release greenhouse gases. We report on the transition of terrestrial to submarine permafrost at a site where the timing of inundation can be inferred from the rate of coastline retreat. On Muostakh Island in the central Laptev Sea, East Siberia, changes in annual coastline position have been measured for decades and vary highly spatially. We hypothesize that these rates are inversely related to the inclination of the upper surface of submarine ice-bonded permafrost (IBP) based on the consequent duration of inundation with increasing distance from the shoreline. We compared rapidly eroding and stable coastal sections of Muostakh Island and find permafrost-table inclinations, determined using direct current resistivity, of 1 and 5 %, respectively. Determinations of submarine IBP depth from a drilling transect in the early 1980s were compared to resistivity profiles from 2011. Based on boreholes drilled in 1982–1983, the thickness of unfrozen sediment overlying the IBP increased from 0 up to 14 m below sea level with increasing distance from the shoreline. The geoelectrical profiles showed thickening of the unfrozen sediment overlying ice-bonded permafrost over the 28 years since drilling took place. Parts of our geoelectrical profiles trace permafrost flooded, and showed that IBP degradation rates decreased from over 0.6 m a−1 following inundation to around 0.1 m a−1 as the duration of inundation increased to 250 years. We discuss that long-term rates are expected to be less than these values, as the depth to the IBP increases and thermal and pore water solute concentration gradients over depth decrease. For this region, it can be summarized that recent increases in coastal erosion rate and longer-term changes to benthic temperature and salinity regimes are expected to affect the depth to submarine permafrost, leading to coastal regions with shallower IBP.

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