Late Wisconsin iceberg-calving rates and ice-sheet mass balance reconstructed from paleo-sea levels, Mount Desert Island, Maine

Geology ◽  
1991 ◽  
Vol 19 (2) ◽  
pp. 155 ◽  
Author(s):  
Thomas V. Lowell
Keyword(s):  
Mass Balance ◽  
Ice Sheet ◽  
Sea Levels ◽  
Iceberg Calving ◽  
Desert Island ◽  
Ice Sheet Mass Balance

Greenland Ice Sheet Mass Balance Reconstruction. Part III: Marine Ice Loss and Total Mass Balance (1840–2010)

2013 ◽  
Vol 26 (18) ◽  
pp. 6990-7002 ◽  
Author(s):  
Jason E. Box ◽  
William Colgan
Keyword(s):  
Mass Balance ◽  
Sea Level ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Mass Gain ◽  
Surface Mass ◽  
Meltwater Runoff ◽  
Glacier Front ◽  
Iceberg Calving ◽  
Ice Sheet Mass Balance

Abstract Greenland ice sheet mass loss to the marine environment occurs by some combination of iceberg calving and underwater melting (referred to here as marine ice loss, LM). This study quantifies the relation between LM and meltwater runoff (R) at the ice sheet scale. A theoretical basis is presented explaining how variability in R can be expected to govern much of the LM variability over annual to decadal time scales. It is found that R enhances LM through three processes: 1) increased glacier discharge by ice warming–softening and basal lubrication–sliding; 2) increased calving susceptibility through undercutting glacier front geometry and reducing ice integrity; and 3) increased underwater melting from forcing marine convection. Applying a semiempirical LM f(R) parameterization to a surface mass balance reconstruction enables total ice sheet mass budget closure over the 1840–2010 period. The estimated cumulative 171-yr net ice sheet sea level contribution is 25 ± 10 mm, the rise punctuated by periods of ice sheet net mass gain (sea level drawdown) (1893–1900, 1938–47, and 1972–98). The sea level contribution accelerated at 27.6 mm yr−1 century−1 over the entire reconstruction, reaching a peak sea level rise contribution of 6.1 mm decade−1 during 2002–10.

Greenland ice sheet mass balance: a review

2015 ◽  
Vol 78 (4) ◽  
pp. 046801 ◽  
Author(s):  
Shfaqat A Khan ◽  
Andy Aschwanden ◽  
Anders A Bjørk ◽  
John Wahr ◽  
Kristian K Kjeldsen ◽  
...  
Keyword(s):  
Mass Balance ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Ice Sheet Mass Balance

scholarly journals Monitoring southwest Greenland’s ice sheet melt with ambient seismic noise

2016 ◽  
Vol 2 (5) ◽  
pp. e1501538 ◽  
Author(s):  
Aurélien Mordret ◽  
T. Dylan Mikesell ◽  
Christopher Harig ◽  
Bradley P. Lipovsky ◽  
Germán A. Prieto
Keyword(s):  
Mass Loss ◽  
Mass Balance ◽  
Sea Level ◽  
Seismic Noise ◽  
Seismic Velocity ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Sea Level Changes ◽  
Ice Sheet Mass Balance ◽  
Velocity Changes

The Greenland ice sheet presently accounts for ~70% of global ice sheet mass loss. Because this mass loss is associated with sea-level rise at a rate of 0.7 mm/year, the development of improved monitoring techniques to observe ongoing changes in ice sheet mass balance is of paramount concern. Spaceborne mass balance techniques are commonly used; however, they are inadequate for many purposes because of their low spatial and/or temporal resolution. We demonstrate that small variations in seismic wave speed in Earth’s crust, as measured with the correlation of seismic noise, may be used to infer seasonal ice sheet mass balance. Seasonal loading and unloading of glacial mass induces strain in the crust, and these strains then result in seismic velocity changes due to poroelastic processes. Our method provides a new and independent way of monitoring (in near real time) ice sheet mass balance, yielding new constraints on ice sheet evolution and its contribution to global sea-level changes. An increased number of seismic stations in the vicinity of ice sheets will enhance our ability to create detailed space-time records of ice mass variations.

scholarly journals Ocean-driven thinning enhances iceberg calving and retreat of Antarctic ice shelves

2015 ◽  
Vol 112 (11) ◽  
pp. 3263-3268 ◽  
Author(s):  
Yan Liu ◽  
John C. Moore ◽  
Xiao Cheng ◽  
Rupert M. Gladstone ◽  
Jeremy N. Bassis ◽  
...  
Keyword(s):  
Mass Loss ◽  
Mass Balance ◽  
Climate Forcing ◽  
Empirical Estimate ◽  
Positive Mass ◽  
Ice Shelves ◽  
Total Mass Loss ◽  
Rapid Changes ◽  
Iceberg Calving ◽  
Ice Sheet Mass Balance

Iceberg calving from all Antarctic ice shelves has never been directly measured, despite playing a crucial role in ice sheet mass balance. Rapid changes to iceberg calving naturally arise from the sporadic detachment of large tabular bergs but can also be triggered by climate forcing. Here we provide a direct empirical estimate of mass loss due to iceberg calving and melting from Antarctic ice shelves. We find that between 2005 and 2011, the total mass loss due to iceberg calving of 755 ± 24 gigatonnes per year (Gt/y) is only half the total loss due to basal melt of 1516 ± 106 Gt/y. However, we observe widespread retreat of ice shelves that are currently thinning. Net mass loss due to iceberg calving for these ice shelves (302 ± 27 Gt/y) is comparable in magnitude to net mass loss due to basal melt (312 ± 14 Gt/y). Moreover, we find that iceberg calving from these decaying ice shelves is dominated by frequent calving events, which are distinct from the less frequent detachment of isolated tabular icebergs associated with ice shelves in neutral or positive mass balance regimes. Our results suggest that thinning associated with ocean-driven increased basal melt can trigger increased iceberg calving, implying that iceberg calving may play an overlooked role in the demise of shrinking ice shelves, and is more sensitive to ocean forcing than expected from steady state calving estimates.

scholarly journals Constraining GRACE-derived cryosphere-attributed signal to irregularly shaped ice-covered areas

2013 ◽  
Vol 7 (6) ◽  
pp. 1901-1914 ◽  
Author(s):  
W. Colgan ◽  
S. Luthcke ◽  
W. Abdalati ◽  
M. Citterio
Keyword(s):  
Monte Carlo ◽  
Mass Loss ◽  
Mass Balance ◽  
Spherical Harmonic ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Ice Caps ◽  
Ice Coverage ◽  
Ice Sheet Mass Balance ◽  
Harmonic Representation

Abstract. We use a Monte Carlo approach to invert a spherical harmonic representation of cryosphere-attributed mass change in order to infer the most likely underlying mass changes within irregularly shaped ice-covered areas at nominal 26 km resolution. By inverting a spherical harmonic representation through the incorporation of additional fractional ice coverage information, this approach seeks to eliminate signal leakage between non-ice-covered and ice-covered areas. The spherical harmonic representation suggests a Greenland mass loss of 251 ± 25 Gt a−1 over the December 2003 to December 2010 period. The inversion suggests 218 ± 20 Gt a−1 was due to the ice sheet proper, and 34 ± 5 Gt a−1 (or ~14%) was due to Greenland peripheral glaciers and ice caps (GrPGICs). This mass loss from GrPGICs exceeds that inferred from all ice masses on both Ellesmere and Devon islands combined. This partition therefore highlights that GRACE-derived "Greenland" mass loss cannot be taken as synonymous with "Greenland ice sheet" mass loss when making comparisons with estimates of ice sheet mass balance derived from techniques that sample only the ice sheet proper.

Trends and projections in ice sheet mass balance

2020 ◽  
Author(s):  
Andrew Shepherd ◽  
Keyword(s):  
Mass Balance ◽  
Sea Level Rise ◽  
Sea Level ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Ice Dynamics ◽  
Surface Mass ◽  
Sea Levels ◽  
Global Sea Level

<p>In recent decades, the Antarctic and Greenland Ice Sheets have been major contributors to global sea-level rise and are expected to be so in the future. Although increases in glacier flow and surface melting have been driven by oceanic and atmospheric warming, the degree and trajectory of today’s imbalance remain uncertain. Here we compare and combine 26 individual satellite records of changes in polar ice sheet volume, flow and gravitational potential to produce a reconciled estimate of their mass balance. <strong>Since the early 1990’s, ice losses from Antarctica and Greenland have caused global sea-levels to rise by 18.4 millimetres, on average, and there has been a sixfold increase in the volume of ice loss over time. Of this total, 41 % (7.6 millimetres) originates from Antarctica and 59 % (10.8 millimetres) is from Greenland. In this presentation, we compare our reconciled estimates of Antarctic and Greenland ice sheet mass change to IPCC projection of sea level rise to assess the model skill in predicting changes in ice dynamics and surface mass balance.  </strong>Cumulative ice losses from both ice sheets have been close to the IPCC’s predicted rates for their high-end climate warming scenario, which forecast an additional 170 millimetres of global sea-level rise by 2100 when compared to their central estimate.</p>

Ice sheet mass balance and sea level

2009 ◽  
Vol 21 (5) ◽  
pp. 413-426 ◽  
Author(s):  
I. Allison ◽  
R.B. Alley ◽  
H.A. Fricker ◽  
R.H. Thomas ◽  
R.C. Warner
Keyword(s):  
Mass Balance ◽  
Sea Level Rise ◽  
Sea Level ◽  
Average Rate ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Measurement Technology ◽  
Satellite Gravity ◽  
Intergovernmental Panel ◽  
Ice Sheet Mass Balance

AbstractDetermining the mass balance of the Greenland and Antarctic ice sheets (GIS and AIS) has long been a major challenge for polar science. But until recent advances in measurement technology, the uncertainty in ice sheet mass balance estimates was greater than any net contribution to sea level change. The Fourth Assessment Report of the Intergovernmental Panel on Climate Change (AR4) was able, for the first time, to conclude that, taken together, the GIS and AIS have probably been contributing to sea level rise over the period 1993–2003 at an average rate estimated at 0.4 mm yr-1. Since the cut-off date for work included in AR4, a number of further studies of the mass balance of GIS and AIS have been made using satellite altimetry, satellite gravity measurements and estimates of mass influx and discharge using a variety of techniques. Overall, these studies reinforce the conclusion that the ice sheets are contributing to present sea level rise, and suggest that the rate of loss from GIS has recently increased. The largest unknown in the projections of sea level rise over the next century is the potential for rapid dynamic collapse of ice sheets.

scholarly journals Changes in speed near the onset of Bindschadler Ice Stream, West Antarctica

2007 ◽  
Vol 46 ◽  
pp. 83-86 ◽  
Author(s):  
J. Paul Winberry ◽  
Sridhar Anandakrishnan ◽  
Andrew M. Smith
Keyword(s):  
Velocity Field ◽  
Mass Balance ◽  
Temporal Pattern ◽  
Ice Sheet ◽  
West Antarctica ◽  
Ice Stream ◽  
Ice Sheet Mass Balance ◽  
The Stability ◽  
Inland Ice ◽  
Onset Location

AbstractIce-stream velocities can change rapidly. Understanding the spatial and temporal pattern of these changes and the forcings responsible is essential for predicting ice-sheet mass balance. Inland migration of the onset location will lead to more efficient drainage of inland ice. One way to monitor the stability of the onset location is to investigate changes in the velocity field. We report on the velocity near the onset of Bindschadler Ice Stream, West Antarctica, in 2002 and compare these data to the velocity measured in 1996. Mean annual velocities were determined by measuring the GPS position of markers during consecutive seasons. We compare our results with similar measurements from 1996 to investigate temporal changes in this ice-stream onset. Our results indicate that only minimal changes have occurred in the speed of the ice stream between 1996 and 2002.

scholarly journals A new approach to estimate ice dynamic rates using satellite observations in East Antarctica

2016 ◽  
Author(s):  
Bianca Kallenberg ◽  
Paul Tregoning ◽  
Janosch F. Hoffmann ◽  
Rhys Hawkins ◽  
Anthony Purcell ◽  
...  
Keyword(s):  
Mass Balance ◽  
Satellite Altimetry ◽  
Ice Sheet ◽  
East Antarctica ◽  
Surface Mass Balance ◽  
Antarctic Ice Sheet ◽  
Surface Mass ◽  
Elevation Changes ◽  
Ice Sheet Mass Balance ◽  
The Antarctic

Abstract. Mass balance changes of the Antarctic ice sheet are of significant interest due to its sensitivity to climatic changes and its contribution to changes in global sea level. While regional climate models successfully estimate mass input due to snowfall, it remains difficult to estimate the amount of mass loss due to ice dynamic processes. It's often been assumed that changes in ice dynamic rates only need to be considered when assessing long term ice sheet mass balance; however, two decades of satellite altimetry observations reveal that the Antarctic ice sheet changes unexpectedly and much more dynamically than previously expected. Despite available estimates on ice dynamic rates obtained from radar altimetry, information about changes in ice dynamic rates are still limited, especially in East Antarctica. Without understanding ice dynamic rates it is not possible to properly assess changes in ice sheet mass balance, surface elevation or to develop ice sheet models. In this study we investigate the possibility of estimating ice dynamic rates by removing modelled rates of surface mass balance, firn compaction and bedrock uplift from satellite altimetry and gravity observations. With similar rates of ice discharge acquired from two different satellite missions we show that it is possible to obtain an approximation of ice dynamic rates by combining altimetry and gravity observations. Thus, surface elevation changes due to surface mass balance, firn compaction and ice dynamic rates can be modelled and correlate with observed elevation changes from satellite altimetry.

scholarly journals CMIP5 temperature biases and 21st century warming around the Antarctic coast

2016 ◽  
Vol 57 (73) ◽  
pp. 69-78 ◽  
Author(s):  
Christopher M. Little ◽  
Nathan M. Urban
Keyword(s):  
Mass Balance ◽  
21St Century ◽  
General Circulation ◽  
Large Scale ◽  
Ice Sheet ◽  
Coupled Model ◽  
General Circulation Models ◽  
Ensemble Mean ◽  
Rcp 8.5 ◽  
Ice Sheet Mass Balance

ABSTRACTProjections of ice-sheet mass balance require regional ocean warming projections derived from atmosphere-ocean general circulation models (AOGCMs). However, the coarse resolution of AOGCMs: (1) may lead to systematic or AOGCM-specific biases and (2) makes it difficult to identify relevant water masses. Here, we employ a large-scale metric of Antarctic Shelf Bottom Water (ASBW) to investigate circum-Antarctic temperature biases and warming projections in 19 different Coupled Model Intercomparison Project Phase 5 (CMIP5) AOGCMs forced with two different ‘representative concentration pathways’ (RCPs). For high-emissions RCP 8.5, the ensemble mean 21st century ASBW warming is 0.66, 0.74 and 0.58°C for the Amundsen, Ross and Weddell Seas (AS, RS and WS), respectively. RCP 2.6 ensemble mean projections are substantially lower: 0.21, 0.26, and 0.19°C. All distributions of regional ASBW warming are positively skewed; for RCP 8.5, four AOGCMs project warming of greater than 1.8°C in the RS. Across the ensemble, there is a strong, RCP-independent, correlation between WS and RS warming. AS warming is more closely linked to warming in the Southern Ocean. We discuss possible physical mechanisms underlying the spatial patterns of warming and highlight implications of these results on strategies for forcing ice-sheet mass balance projections.

Sign in / Sign up

Export Citation Format

Share Document