Acceleration of the contribution of the Greenland and Antarctic ice sheets to sea level rise

Rignot, Eric; Velicogna, I.; Broeke, M. R. van den; Monaghan, Andrew J.; Lenaerts, Jan T. M.

doi:10.1029/2011gl046583

Cited by 990 publications

(959 citation statements)

References 29 publications

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“…This result is supported by field observations of strand cracks (Swithinbank, 1955) between the seismic sites. Furthermore, the DInSAR grounding line (Rignot et al, 2011) indicates that islands are buried within the ice shelf in this region (visible in Fig. 1, directly east of Marmelon Point).…”

Section: Marmelon Pointmentioning

confidence: 95%

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Seabed topography beneath Larsen C Ice Shelf from seismic soundings

et al. 2014

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Abstract. Seismic reflection soundings of ice thickness and seabed depth were acquired on the Larsen C Ice Shelf in order to test a sub-ice shelf bathymetry model derived from the inversion of IceBridge gravity data. A series of lines was collected, from the Churchill Peninsula in the north to the Joerg Peninsula in the south, and also towards the ice front. Sites were selected using the bathymetry model derived from the inversion of free-air gravity data to indicate key regions where sub-ice shelf oceanic circulation may be affected by ice draft and seabed depth. The seismic velocity profile in the upper 100 m of firn and ice was derived from shallow refraction surveys at a number of locations. Measured temperatures within the ice column and at the ice base were used to define the velocity profile through the remainder of the ice column. Seismic velocities in the water column were derived from previous in situ measurements. Uncertainties in ice and water cavity thickness are in general <10 m. Compared with the seismic measurements, the rootmean-square error in the gravimetrically derived bathymetry at the seismic sites is 162 m. The seismic profiles prove the non-existence of several bathymetric features that are indicated in the gravity inversion model, significantly modifying the expected oceanic circulation beneath the ice shelf. Similar features have previously been shown to be highly significant in affecting basal melt rates predicted by ocean models. The discrepancies between the gravity inversion results and the seismic bathymetry are attributed to the assumption of uniform geology inherent in the gravity inversion process and also the sparsity of IceBridge flight lines. Results indicate that care must be taken when using bathymetry models derived by the inversion of free-air gravity anomalies. The bathymetry results presented here will be used to improve existing sub-ice shelf ocean circulation models.

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Section: Marmelon Pointmentioning

confidence: 95%

“…Red circles are sites of previously measured ice thickness and water depth: JK93 Seismic (King et al, 1993); JK95 Seismic (Jarvis and King, 1995); LSN/LSS BAS Moorings (Nicholls et al, 2012); J10 Seismic . The grounding line as derived from DInSAR data (Rignot et al, 2011) is represented by the thick black coastline.…”

Section: Introductionmentioning

confidence: 99%

Seabed topography beneath Larsen C Ice Shelf from seismic soundings

et al. 2014

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“…Combined observational and model studies show that increased meltwater runoff, and solid ice discharge through the acceleration of marine-terminating outlet glaciers Nick et al, 2009;Fettweis et al, 2011;Rignot et al, 2011), account for ∼ 60 and ∼ 40 % respectively of the recent GrIS mass loss (Rignot et al, 2008;Van den Broeke et al, 2009;Enderlin and Howat, 2013).…”

Section: Introductionmentioning

confidence: 99%

Evaluation of the updated regional climate model RACMO2.3: summer snowfall impact on the Greenland Ice Sheet

et al. 2015

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Abstract. We discuss Greenland Ice Sheet (GrIS) surface mass balance (SMB) differences between the updated polar version of the RACMO climate model (RACMO2.3) and the previous version (RACMO2.1). Among other revisions, the updated model includes an adjusted rainfall-to-snowfall conversion that produces exclusively snowfall under freezing conditions; this especially favours snowfall in summer. Summer snowfall in the ablation zone of the GrIS has a pronounced effect on melt rates, affecting modelled GrIS SMB in two ways. By covering relatively dark ice with highly reflective fresh snow, these summer snowfalls have the potential to locally reduce melt rates in the ablation zone of the GrIS through the snow-albedo-melt feedback. At larger scales, SMB changes are driven by differences in orographic precipitation following a shift in large-scale circulation, in combination with enhanced moisture to precipitation conversion for warm to moderately cold conditions. A detailed comparison of model output with observations from automatic weather stations, ice cores and ablation stakes shows that the model update generally improves the simulated SMBelevation gradient as well as the representation of the surface energy balance, although significant biases remain.

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“…After a 30-yr period during which the GrIS was in approximate mass balance (i.e. the mass gain by precipitation was approximately equal to the mass loss by surface runoff and solid ice discharge), the mass balance has turned negative in the last 20 yr, with a larger melt extent (Fettweis et al, 2011), increasing surface runoff Hanna et al, 2008) and increased glacier discharge (Nick et al, 2009;Rignot et al, 2011). In the last decade, contributions made to the total mass loss of ∼ 2400 Gt, were for ∼ 60 % accounted for by enhanced runoff and for ∼ 40 % by enhanced discharge Rignot et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

Sensitivity of Greenland Ice Sheet surface mass balance to surface albedo parameterization: a study with a regional climate model

et al. 2012

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Abstract. We present a sensitivity study of the surface mass balance (SMB) of the Greenland Ice Sheet, as modeled using a regional atmospheric climate model, to various parameter settings in the albedo scheme. The snow albedo scheme uses grain size as a prognostic variable and further depends on cloud cover, solar zenith angle and black carbon concentration. For the control experiment the overestimation of absorbed shortwave radiation (+6 %) at the K-transect (west Greenland) for the period 2004-2009 is considerably reduced compared to the previous density-dependent albedo scheme (+22 %). To simulate realistic snow albedo values, a small concentration of black carbon is needed, which has strongest impact on melt in the accumulation area. A background ice albedo field derived from MODIS imagery improves the agreement between the modeled and observed SMB gradient along the K-transect. The effect of enhanced meltwater retention and refreezing is a decrease of the albedo due to an increase in snow grain size. As a secondary effect of refreezing the snowpack is heated, enhancing melt and further lowering the albedo. Especially in a warmer climate this process is important, since it reduces the refreezing potential of the firn layer that covers the Greenland Ice Sheet.

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Acceleration of the contribution of the Greenland and Antarctic ice sheets to sea level rise

Cited by 990 publications

References 29 publications

Seabed topography beneath Larsen C Ice Shelf from seismic soundings

Seabed topography beneath Larsen C Ice Shelf from seismic soundings

Evaluation of the updated regional climate model RACMO2.3: summer snowfall impact on the Greenland Ice Sheet

Sensitivity of Greenland Ice Sheet surface mass balance to surface albedo parameterization: a study with a regional climate model

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