Significant thinning of the south Greenland Ice Sheet margin

Weather ◽  
2006 ◽  
Vol 61 (4) ◽  
pp. 102-105 ◽  
Author(s):  
Carl Egede Bøggild ◽  
Steffen Podlech
Keyword(s):  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
The South

scholarly journals Oceanic heat delivery via Kangerdlugssuaq Fjord to the south-east Greenland ice sheet

2014 ◽  
Vol 119 (2) ◽  
pp. 631-645 ◽  
Author(s):  
Mark E. Inall ◽  
Tavi Murray ◽  
Finlo R. Cottier ◽  
Kilian Scharrer ◽  
Timothy J. Boyd ◽  
...  
Keyword(s):  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
The South ◽  
East Greenland

scholarly journals Glacier algae accelerate melt rates on the south-western Greenland Ice Sheet

2020 ◽  
Vol 14 (1) ◽  
pp. 309-330 ◽  
Author(s):  
Joseph M. Cook ◽  
Andrew J. Tedstone ◽  
Christopher Williamson ◽  
Jenine McCutcheon ◽  
Andrew J. Hodson ◽  
...  
Keyword(s):  
Sea Level ◽  
Algal Blooms ◽  
Ice Sheet ◽  
Algal Growth ◽  
Greenland Ice Sheet ◽  
Radiation Absorption ◽  
Transfer Model ◽  
High Biomass ◽  
The South ◽  
Ice Surface

Abstract. Melting of the Greenland Ice Sheet (GrIS) is the largest single contributor to eustatic sea level and is amplified by the growth of pigmented algae on the ice surface, which increases solar radiation absorption. This biological albedo-reducing effect and its impact upon sea level rise has not previously been quantified. Here, we combine field spectroscopy with a radiative-transfer model, supervised classification of unmanned aerial vehicle (UAV) and satellite remote-sensing data, and runoff modelling to calculate biologically driven ice surface ablation. We demonstrate that algal growth led to an additional 4.4–6.0 Gt of runoff from bare ice in the south-western sector of the GrIS in summer 2017, representing 10 %–13 % of the total. In localized patches with high biomass accumulation, algae accelerated melting by up to 26.15±3.77 % (standard error, SE). The year 2017 was a high-albedo year, so we also extended our analysis to the particularly low-albedo 2016 melt season. The runoff from the south-western bare-ice zone attributed to algae was much higher in 2016 at 8.8–12.2 Gt, although the proportion of the total runoff contributed by algae was similar at 9 %–13 %. Across a 10 000 km2 area around our field site, algae covered similar proportions of the exposed bare ice zone in both years (57.99 % in 2016 and 58.89 % in 2017), but more of the algal ice was classed as “high biomass” in 2016 (8.35 %) than 2017 (2.54 %). This interannual comparison demonstrates a positive feedback where more widespread, higher-biomass algal blooms are expected to form in high-melt years where the winter snowpack retreats further and earlier, providing a larger area for bloom development and also enhancing the provision of nutrients and liquid water liberated from melting ice. Our analysis confirms the importance of this biological albedo feedback and that its omission from predictive models leads to the systematic underestimation of Greenland's future sea level contribution, especially because both the bare-ice zones available for algal colonization and the length of the biological growth season are set to expand in the future.

scholarly journals Melting of Northern Greenland during the last interglaciation

2012 ◽  
Vol 6 (6) ◽  
pp. 1239-1250 ◽  
Author(s):  
A. Born ◽  
K. H. Nisancioglu
Keyword(s):  
Climate Model ◽  
Three Dimensional ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Large Mass ◽  
Climate Data ◽  
Coupled Climate Model ◽  
The South ◽  
High Accumulation ◽  
Positive Feedbacks

Abstract. Using simulated climate data from the comprehensive coupled climate model IPSL CM4, we simulate the Greenland ice sheet (GrIS) during the Eemian interglaciation with the three-dimensional ice sheet model SICOPOLIS. The Eemian is a period 126 000 yr before present (126 ka) with Arctic temperatures comparable to projections for the end of this century. In our simulation, the northeastern part of the GrIS is unstable and retreats significantly, despite moderate melt rates. This result is found to be robust to perturbations within a wide parameter space of key parameters of the ice sheet model, the choice of initial ice temperature, and has been reproduced with climate forcing from a second coupled climate model, the CCSM3. It is shown that the northeast GrIS is the most vulnerable. Even a small increase in melt removes many years of ice accumulation, giving a large mass imbalance and triggering the strong ice-elevation feedback. Unlike the south and west, melting in the northeast is not compensated by high accumulation. The analogy with modern warming suggests that in coming decades, positive feedbacks could increase the rate of mass loss of the northeastern GrIS, exceeding the recent observed thinning rates in the south.

scholarly journals Melting of Northern Greenland during the last interglacial

2011 ◽  
Vol 5 (6) ◽  
pp. 3517-3539 ◽  
Author(s):  
A. Born ◽  
K. H. Nisancioglu
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Last Interglacial ◽  
The South ◽  
High Accumulation ◽  
Positive Feedbacks ◽  
Geological Past

Abstract. The Greenland ice sheet (GrIS) is losing mass at an increasing rate, making it the primary contributor to global eustatic sea level rise. Large melting areas and rapid thinning at its margins has raised concerns about its stability. However, it is conceivable that these observations represent the transient adjustment of the fastest reacting parts of the ice sheet, masking slower processes that dominate the long term fate of the GrIS and its contribution to sea level rise. Studies of the geological past provide valuable information on the long term response of the GrIS to warm periods. We simulate the GrIS during the Eemian interglacial, a period 126 000 yr before present (126 ka) with Arctic temperatures comparable to projections for the end of this century. The northeastern part of the GrIS is unstable and retreats significantly, despite moderate melt rates. Unlike the south and west, strong melting in the northeast is not compensated by high accumulation, or fast ice flow. The analogy with the present warming suggests that in coming decades, positive feedbacks could increase the rate of mass loss of the northeastern GrIS, exceeding the currently observed melting in the south.

The effect of a shift in the atmospheric energy transport scales on the Greenland ice sheet surface mass balance

2021 ◽  
Author(s):  
Tuomas Ilkka Henrikki Heiskanen
Keyword(s):  
Mass Balance ◽  
Heat Transport ◽  
Latent Heat ◽  
Energy Transport ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Surface Mass Balance ◽  
Synoptic Scale ◽  
The South ◽  
Surface Mass

<p> Climate change in the Arctic is likely to lead to a significant melting of ice sheets and glaciers. This will be an important driving<br>  mechanism for future sea-level rise. During the last decades the Greenland ice sheet has lost mass at an unprecedented rate. <br>  This has lead to the Greenland ice sheet to be an important contributor to sea-level rise. Here we test the hypothesis that a <br>  change in the atmospheric circulation over Greenland contributes to the exceptionally negative surface mass balance observed over the<br>  last decades. </p><p>  The atmospheric transport contributes an amount of energy into the Arctic that is <br>  comparable to that provided directly by the sun. From recently developed Fourier and wavelet based methods it has been found that <br>  the planetary component of the latent heat transport affects that Arctic surface temperatures stronger than the decomposed dry-static <br>  energy transport and the synoptic scale component of the latent heat transport. </p><p>  The south west ablation zone of the Greenland ice-sheet is one of the main contributors to mass loss of the ice-sheet. Comparing <br>  the ablation in this area with patterns of the divergence of latent heat transport shows that similar decadal-scale trends are found <br>  in the surface mass balance and divergence of latent heat transport data. <br>  During the last decades the divergence of latent heat has shifted from <br>  synoptic scale to planetary scale, implying an increased convergence of latent heat transport by synoptic scale waves to the south<br>  west coast of Greenland. </p><p>  Through linear regressions we find that the shift from planetary scale transport convergence to synoptic scale convergence describes<br>  approximately 25 % of the surface mass balance anomaly, since year 2000, in the south west region of Greenland. The total amount <br>  of energy transported into this region has not changed dramatically. Hence this indicates the importance of the systems transporting <br>  the energy or conditions under which the transport by the different wave types take place. <br>  Transport by synoptic scale waves seems to be an important contributor to the surface mass loss of the Greenland ice<br>  sheet. A possible explanation for this is that synoptic scale transport into the ablation zone is associated with warmer conditions<br>  than the planetary component over the same region. Hence providing favorable conditions for ice melting, and possibly a larger <br>  fraction of liquid precipitation. However, why this is so is still a subject we study. <br>  Further we try to identify how different melt driving mechanisms are <br>  associated with both planetary and synoptic scale divergence of energy transport, and which of these lead to the differing effects on<br>  the surface mass balance of the Greenland ice sheet.</p>

scholarly journals 250 000 years in the history of Greenland’s ice sheet

1996 ◽  
Vol 23 ◽  
pp. 359-363
Author(s):  
Magnus Weis ◽  
K. Hutter ◽  
Reinhard Calov
Keyword(s):  
Video Clip ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Atmospheric Temperature ◽  
Finite Difference Approximation ◽  
Difference Approximation ◽  
Heat Conducting ◽  
The South ◽  
Climate History ◽  
Ice Dynamics

Calculations have been conducted for the geometric evolution of the Greenland ice sheet through the last 250 000 years of its climate history. An extended version of Calov’s three-dimensional ice-sheet model is used, i.e. ice is modelled as a viscous thermomechanically coupled fluid with power-law rheology underlain by a heat-conducting lithosphere susceptible to bedrock sinking. The shallow-ice approximation is imposed and the simplified equations are numerically integrated by finite-difference approximation using a centred staggered Arakawa grid. This system is driven by data obtained from the European Greenland Ice Core Project (GRIP). The parameterization of the atmospheric temperature is based on data from Ohmura, precipitation data are taken from Ohmura and Reeh and implemented as shown by Calov. Topographic data for the present observed conditions are those of Letréguilly. The resultant 250 kyear model integrated topography is quite close to that obtained from a steady-state calculation under present conditions. For the calculations presented, Greenland’s north dome seems to be more sensitive to changes in precipitation than its south dome. While the height of the north dome is directly related to the atmospheric temperature, the height of the south dome is inversely related to this variable. In the south, changes in ice dynamics due to a change in ice temperature oppose changes in precipitation. The calculations are visualized in a short video clip that is kept on file with the authors.

First Polish Greenland Expedition 1937: on the 80th anniversary of the event

Polar Record ◽  
2017 ◽  
Vol 53 (4) ◽  
pp. 358-363
Author(s):  
Krzysztof Migała ◽  
Tymoteusz Sawiński ◽  
Jacek Piasecki
Keyword(s):  
Great Influence ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
The South ◽  
80Th Anniversary ◽  
The North ◽  
Post War ◽  
Eastern Edge ◽  
Comprehensive Study

ABSTRACTThis paper describes the first Polish expedition to Greenland in 1937. The fieldwork was carried out in western Greenland at the eastern edge of Arfersiorfik Fjord between Disko Bay in the north and Nordre Strömfjord in the south. The main goal was to undertake a comprehensive study of a fragment of the Greenland ice sheet edge and its foreland focusing on a cartographic survey. The first ever map of this region entitled The Polish expedition to give new names. In the post-war history, expedition members exerted great influence on the development of Polish polar research.

scholarly journals Dark ice dynamics of the south-west Greenland Ice Sheet

2017 ◽  
Author(s):  
Andrew J. Tedstone ◽  
Jonathan L. Bamber ◽  
Joseph M. Cook ◽  
Christopher J. Williamson ◽  
Xavier Fettweis ◽  
...  
Keyword(s):  
Climate Model ◽  
Regional Climate ◽  
Sensible Heat Flux ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Ice Algae ◽  
The South ◽  
Ice Dynamics ◽  
South West ◽  
Algae Growth

Abstract. Runoff from the Greenland Ice Sheet (GrIS) has increased in recent years due largely to declining albedo and enhanced surface melting. Some of the largest declines in GrIS albedo have occurred in the ablation zone of the south-west sector and are associated with the development of 'dark' ice surfaces. Field observations at local scales reveal that a variety of light-absorbing impurities (LAIs) can be present on the surface, ranging from inorganic particulates, to cryoconite materials and ice algae. Meanwhile, satellite observations show that the areal extent of dark ice has varied significantly between recent successive melt seasons. However, the processes that drive such large inter-annual variability in dark ice extent remain essentially unconstrained. At present we are therefore unable to project how the albedo of bare-ice sectors of the GrIS will evolve, causing uncertainty in the projected sea level contribution from the GrIS over the coming decades. Here we use MODIS satellite imagery to examine dark ice dynamics on the south-west GrIS each year from 2000 to 2016. We quantify dark ice in terms of its annual extent, duration, intensity and timing of first appearance. Not only does dark ice extent vary significantly between years, but so too does its duration (from 0 % to > 80 % of June–July–August, JJA), intensity and the timing of its first appearance. Comparison of dark ice dynamics with potential meteorological drivers from the regional climate model MAR reveals that the JJA sensible heat flux, the number of positive minimum-air-temperature days and the timing of bare ice appearance are significant inter-annual synoptic controls. We use these findings to identify the surface processes which are most likely to explain recent dark ice dynamics.We suggest that whilst the spatial distribution of dark ice is best explained by outcropping of particulates from ablating ice, these particulates alone do not drive dark ice dynamics. Instead, they may enable the growth of pigmented ice algal assemblages which cause visible surface darkening, but only when the climatological pre-requisites of liquid meltwater presence and sufficient photosynthetically-active radiation fluxes are met. Further field studies are required to fully constrain the processes by which ice algae growth proceeds and the apparent dependency of algae growth on melt-out particulates.

Trajectory analysis of source regions influencing the south Greenland Ice Sheet during the Dye 3 Gas and Aerosol Sampling Program

1993 ◽  
Vol 27 (17-18) ◽  
pp. 2739-2749 ◽  
Author(s):  
Cliff I Davidson ◽  
Jean-Luc Jaffrezo ◽  
Mitchell J Small ◽  
Peter W Summers ◽  
Marvin P Olson ◽  
...  
Keyword(s):  
Trajectory Analysis ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Aerosol Sampling ◽  
The South ◽  
Source Regions ◽  
Sampling Program
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