Retention of Greenland runoff by refreezing: Implications for projected future sea level change

Pfeffer, W. T.; Meier, Mark F.; Illangasekare, Tissa H.

doi:10.1029/91jc02502

Cited by 215 publications

(246 citation statements)

References 14 publications

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“…While the basic processes associated with meltwater percolation through the snowpack and firn, with the potential for refreezing, have been extensively studied [25][26][27], major advances in recent years have resulted from extensive groundbased field campaigns in the percolation zone of the GrIS. The potential of porous firn to store refrozen meltwater, and thereby delay meltwater runoff, has been highlighted as a mechanism by which sea level rise could be considerably buffered for decades in a warming climate [28].…”

Section: Supraglacial Meltwater Processesmentioning

confidence: 99%

Recent Advances in Our Understanding of the Role of Meltwater in the Greenland Ice Sheet System

Nienow

Sole

Slater

et al. 2017

Curr Clim Change Rep

100

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Purpose of the Review This review discusses the role that meltwater plays within the Greenland ice sheet system. The ice sheet's hydrology is important because it affects mass balance through its impact on meltwater runoff processes and ice dynamics. The review considers recent advances in our understanding of the storage and routing of water through the supraglacial, englacial, and subglacial components of the system and their implications for the ice sheet. Recent Findings There have been dramatic increases in surface meltwater generation and runoff since the early 1990s, both due to increased air temperatures and decreasing surface albedo. Processes in the subglacial drainage system have similarities to valley glaciers and in a warming climate, the efficiency of meltwater routing to the ice sheet margin is likely to increase. The behaviour of the subglacial drainage system appears to limit the impact of increased surface melt on annual rates of ice motion, in sections of the ice sheet that terminate on land, while the large volumes of meltwater routed subglacially deliver significant volumes of sediment and nutrients to downstream ecosystems. Summary Considerable advances have been made recently in our understanding of Greenland ice sheet hydrology and its wider influences. Nevertheless, critical gaps persist both in our understanding of hydrology-dynamics coupling, notably at tidewater glaciers, and in runoff processes which ensure that projecting Greenland's future mass balance remains challenging.

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Section: Supraglacial Meltwater Processesmentioning

confidence: 99%

Recent Advances in Our Understanding of the Role of Meltwater in the Greenland Ice Sheet System

Nienow

Sole

Slater

et al. 2017

Curr Clim Change Rep

100

View full text Add to dashboard Cite

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“…Runoff is calculated using the Pfeffer et al (1991) meltwater retention and refreezing parameterisation with runoff occurring when surplus water is free to percolate downslope once firn is saturated. This model is limited in scope to a single season's accumulation layer, so may overestimate runoff in warm years as meltwater is unable to percolate into the earlier year's accumulation.…”

Section: Polar Mm5mentioning

confidence: 99%

Surface mass balance model intercomparison for the Greenland ice sheet

et al. 2013

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Abstract. A number of high resolution reconstructions of the surface mass balance (SMB) of the Greenland ice sheet (GrIS) have been produced using global re-analyses data extending back to 1958. These reconstructions have been used in a variety of applications but little is known about their consistency with each other and the impact of the downscaling method on the result. Here, we compare four reconstructions for the period 1960-2008 to assess the consistency in regional, seasonal and integrated SMB components. Total SMB estimates for the GrIS are in agreement within 34 % of the four model average when a common ice sheet mask is used. When models' native land/ice/sea masks are used this spread increases to 57 %. Variation in the spread of components of SMB from their mean: runoff 42 % (29 % native masks), precipitation 20 % (24 % native masks), melt 38 % (74 % native masks), refreeze 83 % (142 % native masks) show, with the exception of refreeze, a similar level of agreement once a common mask is used. Previously noted differences in the models' estimates are partially explained by ice sheet mask differences. Regionally there is less agreement, suggesting spatially compensating errors improve the integrated estimates.Modelled SMB estimates are compared with in situ observations from the accumulation and ablation areas. Agreement is higher in the accumulation area than the ablation area suggesting relatively high uncertainty in the estimation of ablation processes. Since the mid-1990s each model estimates a decreasing annual SMB. A similar period of decreasing SMB is also estimated for the period 1960-1972. The earlier decrease is due to reduced precipitation with runoff remaining unchanged, however, the recent decrease is associated with increased precipitation, now more than compensated for by increased melt driven runoff. Additionally, in three of the four models the equilibrium line altitude has risen since the mid-1990s, reducing the accumulation area at a rate of approximately 60 000 km 2 per decade due to increased melting. Improving process representation requires further study but the use of a single accurate ice sheet mask is a logical way to reduce uncertainty among models.

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“…A model-based study by Pfeffer et al (1991) showed that predictions of runoff-induced sea level rise from Greenland that did not consider meltwater refreezing within the firn could be overestimating sea level rise by as much as 5 cm over the next 150 years. The importance of meltwater retention was further highlighted by a study (Harper et al, 2012) based on field measurements obtained in 2007, 2008 and 2009 along the Expédition Glaciologique I nternationale au Groenland (EGIG) line in western Greenland.…”

Section: Introductionmentioning

confidence: 99%

Changes in the firn structure of the western Greenland Ice Sheet caused by recent warming

et al. 2015

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Abstract. Atmospheric warming over the Greenland Ice Sheet during the last 2 decades has increased the amount of surface meltwater production, resulting in the migration of melt and percolation regimes to higher altitudes and an increase in the amount of ice content from refrozen meltwater found in the firn above the superimposed ice zone. Here we present field and airborne radar observations of buried ice layers within the near-surface (0-20 m) firn in western Greenland, obtained from campaigns between 1998 and 2014. We find a sharp increase in firn-ice content in the form of thick widespread layers in the percolation zone, which decreases the capacity of the firn to store meltwater. The estimated total annual ice content retained in the near-surface firn in areas with positive surface mass balance west of the ice divide in Greenland reached a maximum of 74 ± 25 Gt in 2012, compared to the 1958-1999 average of 13 ± 2 Gt, while the percolation zone area more than doubled between 2003 and 2012. Increased melt and column densification resulted in surface lowering averaging −0.80 ± 0.39 m yr −1 between 1800 and 2800 m in the accumulation zone of western Greenland. Since 2007, modeled annual melt and refreezing rates in the percolation zone at elevations below 2100 m surpass the annual snowfall from the previous year, implying that mass gain in the region is retained after melt in the form of refrozen meltwater. If current melt trends over high elevation regions continue, subsequent changes in firn structure will have implications for the hydrology of the ice sheet and related abrupt seasonal densification could become increasingly significant for altimetry-derived ice sheet mass balance estimates.

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Retention of Greenland runoff by refreezing: Implications for projected future sea level change

Cited by 215 publications

References 14 publications

Recent Advances in Our Understanding of the Role of Meltwater in the Greenland Ice Sheet System

Recent Advances in Our Understanding of the Role of Meltwater in the Greenland Ice Sheet System

Surface mass balance model intercomparison for the Greenland ice sheet

Changes in the firn structure of the western Greenland Ice Sheet caused by recent warming

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