scholarly journals Estimation of the Greenland ice sheet surface mass balance during 20th and 21st centuries

2008 ◽  
Vol 2 (2) ◽  
pp. 225-254 ◽  
Author(s):  
X. Fettweis ◽  
E. Hanna ◽  
H. Gallée ◽  
P. Huybrechts ◽  
M. Erpicum
Keyword(s):  
Mass Balance ◽  
Multiple Regression ◽  
21St Century ◽  
General Circulation ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
General Circulation Models ◽  
Climate Simulation ◽  
Surface Mass Balance ◽  
Surface Mass

Abstract. Results from a regional climate simulation (1970–2006) over the Greenland ice sheet (GrIS) reveals that more than 97% of the interannual variability of the modelled Surface Mass Balance (SMB) can be explained by the GrIS summer temperature anomaly and the GrIS annual precipitation anomaly. This multiple regression is then used to empirically estimate the GrIS SMB since 1900 from climatological time series. The projected SMB changes in the 21st century are investigated with the set of simulations performed with atmosphere-ocean general circulation models (AOGCMs) of the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC AR4). These estimates show that the high surface mass loss rates of recent years are not unprecedented in the GrIS history of the last hundred years. The minimum SMB rate seems to have occurred earlier in the 1930s. The AOGCMs project that the SMB rate of the 1930s would be common at the end of 2100. The temperature would be higher than in the 1930s but the increase of accumulation in the 21st century would partly offset the acceleration of surface melt due to the temperature increase. However, these assumptions are based on an empirical multiple regression only validated for recent/current climatic conditions, and the accuracy and time homogeneity of the data sets and AOGCM results used in these estimations constitute a large uncertainty.

scholarly journals Estimation of the Greenland ice sheet surface mass balance for the 20th and 21st centuries

2008 ◽  
Vol 2 (2) ◽  
pp. 117-129 ◽  
Author(s):  
X. Fettweis ◽  
E. Hanna ◽  
H. Gallée ◽  
P. Huybrechts ◽  
M. Erpicum
Keyword(s):  
Mass Balance ◽  
Multiple Regression ◽  
21St Century ◽  
General Circulation ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
General Circulation Models ◽  
Climate Simulation ◽  
Surface Mass Balance ◽  
Surface Mass

Abstract. Results from a regional climate simulation (1970–2006) over the Greenland ice sheet (GrIS) reveals that more than 97% of the interannual variability of the modelled Surface Mass Balance (SMB) can be explained by the GrIS summer temperature anomaly and the GrIS annual precipitation anomaly. This multiple regression is then used to empirically estimate the GrIS SMB since 1900 from climatological time series. The projected SMB changes in the 21st century are investigated with the set of simulations performed with atmosphere-ocean general circulation models (AOGCMs) of the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC AR4). These estimates show that the high surface mass loss rates of recent years are not unprecedented in the GrIS history of the last hundred years. The minimum SMB rate seems to have occurred earlier in the 1930s and corresponds to a zero SMB rate. The AOGCMs project that the SMB rate of the 1930s would be common at the end of 2100. The temperature would be higher than in the 1930s but the increase of accumulation in the 21st century would partly offset the acceleration of surface melt due to the temperature increase. However, these assumptions are based on an empirical multiple regression only validated for recent/current climatic conditions, and the accuracy and time homogeneity of the data sets and AOGCM results used in these estimations constitute a large uncertainty.

scholarly journals Ice-sheet contributions to future sea-level change

2006 ◽  
Vol 364 (1844) ◽  
pp. 1709-1732 ◽  
Author(s):  
J.M Gregory ◽  
P Huybrechts
Keyword(s):  
Mass Balance ◽  
Sea Level ◽  
General Circulation ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
General Circulation Models ◽  
Balance Model ◽  
Surface Mass Balance ◽  
Surface Mass ◽  
Global Average

Accurate simulation of ice-sheet surface mass balance requires higher spatial resolution than is afforded by typical atmosphere–ocean general circulation models (AOGCMs), owing, in particular, to the need to resolve the narrow and steep margins where the majority of precipitation and ablation occurs. We have developed a method for calculating mass-balance changes by combining ice-sheet average time-series from AOGCM projections for future centuries, both with information from high-resolution climate models run for short periods and with a 20 km ice-sheet mass-balance model. Antarctica contributes negatively to sea level on account of increased accumulation, while Greenland contributes positively because ablation increases more rapidly. The uncertainty in the results is about 20% for Antarctica and 35% for Greenland. Changes in ice-sheet topography and dynamics are not included, but we discuss their possible effects. For an annual- and area-average warming exceeding in Greenland and in the global average, the net surface mass balance of the Greenland ice sheet becomes negative, in which case it is likely that the ice sheet would eventually be eliminated, raising global-average sea level by 7 m.

scholarly journals Greenland Ice Sheet Surface Mass-Balance Modeling in a 131-Yr Perspective, 1950–2080

2010 ◽  
Vol 11 (1) ◽  
pp. 3-25 ◽  
Author(s):  
Sebastian H. Mernild ◽  
Glen E. Liston ◽  
Christopher A. Hiemstra ◽  
Jens H. Christensen
Keyword(s):  
Mass Balance ◽  
Sea Level ◽  
General Circulation ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Circulation Model ◽  
Change Scenario ◽  
Surface Mass Balance ◽  
Surface Mass ◽  
Freshwater Runoff

Abstract Fluctuations in the Greenland ice sheet (GrIS) surface mass balance (SMB) and freshwater influx to the surrounding oceans closely follow climate fluctuations and are of considerable importance to the global eustatic sea level rise. A state-of-the-art snow-evolution modeling system (SnowModel) was used to simulate variations in the GrIS melt extent, surface water balance components, changes in SMB, and freshwater influx to the ocean. The simulations are based on the Intergovernmental Panel on Climate Change scenario A1B modeled by the HIRHAM4 regional climate model (RCM) using boundary conditions from the ECHAM5 atmosphere–ocean general circulation model (AOGCM) from 1950 through 2080. In situ meteorological station [Greenland Climate Network (GC-Net) and World Meteorological Organization (WMO) Danish Meteorological Institute (DMI)] observations from inside and outside the GrIS were used to validate and correct RCM output data before they were used as input for SnowModel. Satellite observations and independent SMB studies were used to validate the SnowModel output and confirm the model’s robustness. The authors simulated an ∼90% increase in end-of-summer surface melt extent (0.483 × 106 km2) from 1950 to 2080 and a melt index (above 2000-m elevation) increase of 138% (1.96 × 106 km2 × days). The greatest difference in melt extent occurred in the southern part of the GrIS, and the greatest changes in the number of melt days were seen in the eastern part of the GrIS (∼50%–70%) and were lowest in the west (∼20%–30%). The rate of SMB loss, largely tied to changes in ablation processes, leads to an enhanced average loss of 331 km3 from 1950 to 2080 and an average SMB level of −99 km3 for the period 2070–80. GrIS surface freshwater runoff yielded a eustatic rise in sea level from 0.8 ± 0.1 (1950–59) to 1.9 ± 0.1 mm (2070–80) sea level equivalent (SLE) yr−1. The accumulated GrIS freshwater runoff contribution from surface melting equaled 160-mm SLE from 1950 through 2080.

Sources of Uncertainty in Greenland Surface Mass Balance in the 21st century.

2021 ◽  
Author(s):  
Katharina Meike Holube ◽  
Tobias Zolles ◽  
Andreas Born
Keyword(s):  
Mass Balance ◽  
Greenhouse Gas ◽  
21St Century ◽  
Climate Models ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Surface Mass Balance ◽  
Surface Mass ◽  
Sources Of Uncertainty ◽  
Ensemble Of Simulations

<p>The surface mass balance (SMB) of the Greenland Ice Sheet is subject to considerable uncertainties that complicate predictions of sea-level rise caused by climate change.<br>We examine the SMB of the Greenland Ice Sheet and its uncertainty in the 21st century using a wide ensemble of simulations with the surface energy and mass balance model "BEr<em>ge</em>n Snow SImulator" (BESSI). We conduct simulations for four greenhouse gas emission scenarios using the output of 26 climate models from the sixth phase of the Coupled Model Intercomparison Project (CMIP6) to force BESSI. In addition, the uncertainty of the SMB simulation is estimated by using 16 different parameter sets in our SMB model. The median SMB across climate models, integrated over the ice sheet, decreases for every emission scenario and every parameter set. As expected, the decrease in SMB is stronger for higher greenhouse gas emissions. The uncertainty range in SMB is considerably greater in our ensemble than in other studies that used fewer climate models as forcing. An analysis of the different sources of uncertainty shows that the differences between climate models are the main reason for SMB uncertainty, exceeding even the uncertainty due to the choice of climate scenario. In comparison, the uncertainty caused by the snow model parameters is negligible. The differences between the climate models are most pronounced in the north of Greenland and in the area around the equilibrium line, whereas the ensemble of simulations agrees that the SMB decrease is greatest in the west of Greenland. </p>

scholarly journals The effect of overshooting 1.5 °C global warming on the mass loss of the Greenland ice sheet

2018 ◽  
Vol 9 (4) ◽  
pp. 1169-1189 ◽  
Author(s):  
Martin Rückamp ◽  
Ulrike Falk ◽  
Katja Frieler ◽  
Stefan Lange ◽  
Angelika Humbert
Keyword(s):  
Global Warming ◽  
Mass Loss ◽  
Mass Balance ◽  
Sea Level Rise ◽  
Sea Level ◽  
21St Century ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Surface Mass Balance ◽  
Surface Mass

Abstract. Sea-level rise associated with changing climate is expected to pose a major challenge for societies. Based on the efforts of COP21 to limit global warming to 2.0 ∘C or even 1.5 ∘C by the end of the 21st century (Paris Agreement), we simulate the future contribution of the Greenland ice sheet (GrIS) to sea-level change under the low emission Representative Concentration Pathway (RCP) 2.6 scenario. The Ice Sheet System Model (ISSM) with higher-order approximation is used and initialized with a hybrid approach of spin-up and data assimilation. For three general circulation models (GCMs: HadGEM2-ES, IPSL-CM5A-LR, MIROC5) the projections are conducted up to 2300 with forcing fields for surface mass balance (SMB) and ice surface temperature (Ts) computed by the surface energy balance model of intermediate complexity (SEMIC). The projected sea-level rise ranges between 21–38 mm by 2100 and 36–85 mm by 2300. According to the three GCMs used, global warming will exceed 1.5 ∘C early in the 21st century. The RCP2.6 peak and decline scenario is therefore manually adjusted in another set of experiments to suppress the 1.5 ∘C overshooting effect. These scenarios show a sea-level contribution that is on average about 38 % and 31 % less by 2100 and 2300, respectively. For some experiments, the rate of mass loss in the 23rd century does not exclude a stable ice sheet in the future. This is due to a spatially integrated SMB that remains positive and reaches values similar to the present day in the latter half of the simulation period. Although the mean SMB is reduced in the warmer climate, a future steady-state ice sheet with lower surface elevation and hence volume might be possible. Our results indicate that uncertainties in the projections stem from the underlying GCM climate data used to calculate the surface mass balance. However, the RCP2.6 scenario will lead to significant changes in the GrIS, including elevation changes of up to 100 m. The sea-level contribution estimated in this study may serve as a lower bound for the RCP2.6 scenario, as the currently observed sea-level rise is not reached in any of the experiments; this is attributed to processes (e.g. ocean forcing) not yet represented by the model, but proven to play a major role in GrIS mass loss.

Relative importance of surface mass balance and outlet glacier forcing in ISMIP6 Greenland ice sheet sea-level projections

2021 ◽  
Author(s):  
Heiko Goelzer ◽  
Keyword(s):  
Mass Balance ◽  
Sea Level ◽  
General Circulation ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Surface Mass Balance ◽  
Relative Importance ◽  
Outlet Glacier ◽  
Surface Mass ◽  
The Future

<p>The Greenland ice sheet (GrIS) is one of the largest contributors to global mean sea-level rise today and is expected to continue losing mass in the future under increasing Arctic warming. Mass loss in the future is caused by the thinning and retreat of marine-terminating outlet glaciers and to a larger extent by decreasing surface mass balance (SMB) due to increased surface meltwater runoff. In this paper we study the relative importance of changes in SMB and outlet glacier retreat by means of model simulations that have been performed as part of the Ice Sheet Model Intercomparison Project for CMIP6 (ISMIP6). The effect of the two forcing mechanisms can be separated based on a comparison between full projections and single forcing experiments up to year 2100 for a number of ice sheet models, driving General Circulation Models and two forcing scenarios (RCP2.6 and RCP8.5). We can confirm earlier findings for the high forcing scenario that a compensation between the two processes renders the sea-level contribution from the full experiment lower than the sum of the single forcing experiments.</p>

Projections of 21st century sea-level contribution from the retreat of Humboldt Glacier, North Greenland

2021 ◽  
Author(s):  
Trevor Hillebrand ◽  
Matthew Hoffman ◽  
Mauro Perego ◽  
Stephen Price ◽  
Abby Roat ◽  
...  
Keyword(s):  
Mass Balance ◽  
Sea Level Rise ◽  
Sea Level ◽  
21St Century ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Surface Velocity ◽  
Surface Mass Balance ◽  
Surface Mass ◽  
Basal Friction

<p>Humboldt Glacier drains ~5% of the Greenland Ice Sheet and has retreated and accelerated since the late 1990s. The northern section of the terminus has retreated towards an overdeepening in the glacier bed that extends tens of kilometers towards the ice sheet interior, raising the possibility of a rapid increase in ice discharge and retreat in the near future. Here we investigate the potential 21st century sea-level contribution from Humboldt Glacier with the MPAS-Albany Land Ice (MALI) ice sheet model. First, we optimize the basal friction field using observations of surface velocity and ice surface elevation to obtain an initial condition for the year 2007. Next, we tune parameters for calving, basal friction, and submarine melt to match the observed retreat rates and surface velocity changes. We then simulate glacier evolution to 2100 under a range of climate forcings from the Ice Sheet Model Intercomparison Project for CMIP6 (ISMIP6), using ocean temperatures from the MIROC5 Earth System Model, with surface mass balance and subglacial discharge from MAR3.9/MIROC5. Our simulations predict ~3.5 mm of sea-level rise from the retreat of Humboldt Glacier by 2100 for RCP8.5, and ~1 mm for RCP2.6. The results are insensitive to the choice of calving parameters for grounded ice, but a low stress threshold for calving from floating ice is necessary to initiate retreat. We find that a highly plastic basal friction law is required to reproduce the observed acceleration, but the choice of basal friction law does not have a large effect on the magnitude of sea-level contribution by 2100 because much of the ice is at present close to floatation in the areas that retreat most significantly. Instead, the majority of ice mass loss comes from increasingly negative surface mass balance. Preliminary results from experiments with a subglacial hydrology model suggest that the simple treatment of subglacial discharge used in our 21st century projections (as used in the ISMIP6-Greenland protocol) underestimates spatial variability of melting at the glacier front but gives a reasonable approximation of total melt. When compared to the recent ISMIP6 estimates of 60–140 mm sea-level rise from the entire Greenland Ice Sheet by 2100, our estimate of 3.5 mm from Humboldt Glacier indicates a significant but far from dominant contribution from this single large outlet.</p>

Contemporary (1960–2012) Evolution of the Climate and Surface Mass Balance of the Greenland Ice Sheet

2013 ◽  
Vol 35 (5) ◽  
pp. 1155-1174 ◽  
Author(s):  
J. H. van Angelen ◽  
M. R. van den Broeke ◽  
B. Wouters ◽  
J. T. M. Lenaerts
Keyword(s):  
Mass Balance ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Surface Mass Balance ◽  
Surface Mass

scholarly journals Simulation of the future sea level contribution of Greenland with a new glacial system model

2018 ◽  
Vol 12 (10) ◽  
pp. 3097-3121 ◽  
Author(s):  
Reinhard Calov ◽  
Sebastian Beyer ◽  
Ralf Greve ◽  
Johanna Beckmann ◽  
Matteo Willeit ◽  
...  
Keyword(s):  
Boundary Conditions ◽  
Surface Temperature ◽  
Mass Balance ◽  
Sea Level Rise ◽  
Sea Level ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
System Model ◽  
Surface Mass Balance ◽  
Surface Mass

Abstract. We introduce the coupled model of the Greenland glacial system IGLOO 1.0, including the polythermal ice sheet model SICOPOLIS (version 3.3) with hybrid dynamics, the model of basal hydrology HYDRO and a parameterization of submarine melt for marine-terminated outlet glaciers. The aim of this glacial system model is to gain a better understanding of the processes important for the future contribution of the Greenland ice sheet to sea level rise under future climate change scenarios. The ice sheet is initialized via a relaxation towards observed surface elevation, imposing the palaeo-surface temperature over the last glacial cycle. As a present-day reference, we use the 1961–1990 standard climatology derived from simulations of the regional atmosphere model MAR with ERA reanalysis boundary conditions. For the palaeo-part of the spin-up, we add the temperature anomaly derived from the GRIP ice core to the years 1961–1990 average surface temperature field. For our projections, we apply surface temperature and surface mass balance anomalies derived from RCP 4.5 and RCP 8.5 scenarios created by MAR with boundary conditions from simulations with three CMIP5 models. The hybrid ice sheet model is fully coupled with the model of basal hydrology. With this model and the MAR scenarios, we perform simulations to estimate the contribution of the Greenland ice sheet to future sea level rise until the end of the 21st and 23rd centuries. Further on, the impact of elevation–surface mass balance feedback, introduced via the MAR data, on future sea level rise is inspected. In our projections, we found the Greenland ice sheet to contribute between 1.9 and 13.0 cm to global sea level rise until the year 2100 and between 3.5 and 76.4 cm until the year 2300, including our simulated additional sea level rise due to elevation–surface mass balance feedback. Translated into additional sea level rise, the strength of this feedback in the year 2100 varies from 0.4 to 1.7 cm, and in the year 2300 it ranges from 1.7 to 21.8 cm. Additionally, taking the Helheim and Store glaciers as examples, we investigate the role of ocean warming and surface runoff change for the melting of outlet glaciers. It shows that ocean temperature and subglacial discharge are about equally important for the melting of the examined outlet glaciers.

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