Fracture and back stress along the Byrd Glacier flowband on the Ross Ice Shelf

Kenneally, James P.; Hughes, Terence J.

doi:10.1017/s0954102004002056

Cited by 9 publications

(12 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…5), with higher backstress near the grounding line, at the confluence of neighboring tributary glaciers, and upstream of ice rises, is consistent with findings for other ice shelves (Thomas, 1973b;Thomas and MacAyeal, 1982;Kenneally and Hughes, 2004). The Bawden and Gipps ice rises contribute locally high backstress to the shelf.…”

Section: Backstress Patternssupporting

confidence: 79%

“…Schoof, 2007), which has motivated a number of recent numerical studies of the relationship between ice shelf buttressing and grounding line stability for a marine ice sheet (Goldberg et al, 2009;Gagliardini et al, 2010;Favier et al, 2012;Gudmundsson, 2013). However, in spite of the widespread recognition of the importance of fractures for the flow and stability of ice shelves (e.g Jezek et al, 1985;Doake and Vaughan, 1991;Vaughan, 1993;van Der Veen, 1998a;Scambos et al, 2000;Kenneally and Hughes, 2004;Larour et al, 2004a;Glasser et al, 2009;Khazendar et al, 2009;Jansen et al, 2010;Albrecht and Levermann, 2012;Luckman et al, 2012;McGrath et al, 2012), little attention has been given to the impact of fractureinduced weakening on ice shelf buttressing.…”

Section: Introductionmentioning

confidence: 99%

“…This development introduced a crack length explicitly into the formulation of Thomas (1973a), though it only applies in a field of closely spaced crevasses. Rist et al (2002) and Kenneally and Hughes (2004) similarly invoked backstress to rectify the discrepancy between measured and predicted basal crevasse penetration heights, this time using Linear Elastic Fracture Mechanics (LEFM). In this approach, the crack length enters the framework implicitly through the implied backstress.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Creep deformation and buttressing capacity of damaged ice shelves: theory and application to Larsen C ice shelf

et al. 2013

View full text Add to dashboard Cite

Abstract. Around the perimeter of Antarctica, much of the ice sheet discharges to the ocean through floating ice shelves. The buttressing provided by ice shelves is critical for modulating the flux of ice into the ocean, and the presently observed thinning of ice shelves is believed to be reducing their buttressing capacity and contributing to the acceleration and thinning of the grounded ice sheet. However, relatively little attention has been paid to the role that fractures play in the ability of ice shelves to sustain and transmit buttressing stresses. Here, we present a new framework for quantifying the role that fractures play in the creep deformation and buttressing capacity of ice shelves. We apply principles of continuum damage mechanics to derive a new analytical relation for the creep of an ice shelf that accounts for the softening influence of fractures on longitudinal deformation using a state damage variable. We use this new analytical relation, combined with a temperature calculation for the ice, to partition an inverse method solution for ice shelf rigidity into independent solutions for softening damage and stabilizing backstress. Using this new approach, field and remote sensing data can be utilized to monitor the structural integrity of ice shelves, their ability to buttress the flow of ice at the grounding line, and thus their indirect contribution to ice sheet mass balance and global sea level. We apply this technique to the Larsen C ice shelf using remote sensing and Operation IceBridge data, finding damage in areas with known crevasses and rifts. Backstress is highest near the grounding line and upstream of ice rises, in agreement with patterns observed on other ice shelves. The ice in contact with the Bawden ice rise is weakened by fractures, and additional damage or thinning in this area could diminish the backstress transmitted upstream. We model the consequences for the ice shelf if it loses contact with this small ice rise, finding that flow speeds would increase by 25 % or more over an area the size of the former Larsen B ice shelf. Such a perturbation could potentially destabilize the northern part of Larsen C along pre-existing lines of weakness, highlighting the importance of the feedback between buttressing and fracturing in an ice shelf.

show abstract

Section: Backstress Patternssupporting

confidence: 79%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Creep deformation and buttressing capacity of damaged ice shelves: theory and application to Larsen C ice shelf

et al. 2013

View full text Add to dashboard Cite

show abstract

“…a −1 , similar to the surface mass balance. However, w b varies spatially over a wide range, from close to 0 over much of the central portion of the ice shelf to over 10 m a −1 near the deep grounding line of Byrd Glacier (Kenneally & Hughes, 2004) and in a channel near Whillans Ice Plain (Marsh et al, 2016). Relatively high basal melt rates of about 1-2 m a −1 have been estimated near the ice shelf front from Lagrangian analyses of ICESat repeat-track laser altimetry (Horgan et al, 2011;Moholdt et al, 2014) and from an autonomous phase-sensitive radio-echo sounder survey in a small region near Ross Island (Stewart et al, 2019).…”

Section: Basal Melting (−48 ± 34 Gt a −1 )mentioning

confidence: 99%

Multidecadal Basal Melt Rates and Structure of the Ross Ice Shelf, Antarctica, Using Airborne Ice Penetrating Radar

et al. 2020

View full text Add to dashboard Cite

Basal melting of ice shelves is a major source of mass loss from the Antarctic Ice Sheet. In situ measurements of ice shelf basal melt rates are sparse, while the more extensive estimates from satellite altimetry require precise information about firn density and characteristics of near‐surface layers. We describe a novel method for estimating multidecadal basal melt rates using airborne ice penetrating radar data acquired during a 3‐year survey of the Ross Ice Shelf. These data revealed an ice column with distinct upper and lower units whose thicknesses change as ice flows from the grounding line toward the ice front. We interpret the lower unit as continental meteoric ice that has flowed across the grounding line and the upper unit as ice formed from snowfall onto the relatively flat ice shelf. We used the ice thickness difference and strain‐induced thickness change of the lower unit between the survey lines, combined with ice velocities, to derive basal melt rates averaged over one to six decades. Our results are similar to satellite laser altimetry estimates for the period 2003–2009, suggesting that the Ross Ice Shelf melt rates have been fairly stable for several decades. We identify five sites of elevated basal melt rates, in the range 0.5–2 m a−1, near the ice shelf front. These hot spots indicate pathways into the sub‐ice‐shelf ocean cavity for warm seawater, likely a combination of summer‐warmed Antarctic Surface Water and modified Circumpolar Deep Water, and are potential areas of ice shelf weakening if the ocean warms.

show abstract

“…The surface of ice shelves is close to sea level, so climate warming could initiate widespread surface melting on the Ross Ice Shelf. This would be accompanied by widening and lengthening of crevasses, some filling with water [ Kenneally and Hughes , , ; Hughes , , Chapter 29], melting in shear zones and rifts, lakes forming on the ice shelf and in the foothills of the Transantarctic Mountains, melting on the slopes with water running to the base of outlet glaciers and possibly increasing the sliding velocity, all of which change the flexural dynamics of the ice shelf in ways that lead to disintegration [ MacAyeal and Sergienko , ]. Then the Ross Sea Embayment would become a calving bay similar to Hudson Bay that carved out the heart of the former Laurentide Ice Sheet that covered much of North America 18,000 years ago and triggered Termination of the last cycle of Quaternary glaciations [ Hughes , ].…”

Section: Causes Of Ice‐shelf Buttressingmentioning

confidence: 99%

Instability of the Antarctic Ross Sea Embayment as climate warms

Hughes

Zhao

Hintz

et al. 2017

Reviews of Geophysics

View full text Add to dashboard Cite

Collapse of the Antarctic Ice Sheet since the Last Glacial Maximum 18,000 years ago is most pronounced in the Ross Sea Embayment, which is partly ice‐free during Antarctic summers, thereby breaching the O‐ring of ice shelves and sea ice surrounding Antarctica that stabilizes the ice sheet. The O‐ring may have vanished during Early Holocene (5000 to 3000 B.C.), Roman (1 to 400 A.D.), and Medieval (900 to 1300 A.D.) warm periods and reappeared during the Little Ice Age (1300 to 1900 A.D.). We postulate further collapse in the embayment during the post‐1900 warming may be forestalled because East Antarctic outlet glaciers “nail” the Ross Ice Shelf to the Transantarctic Mountains so it can resist the push from West Antarctic ice streams. Our hypothesis is examined for Byrd Glacier and a static ice shelf using three modeling experiments having plastic, viscous, and viscoplastic solutions as more data and improved modeling became available. Observed crevasse patterns were not reproduced. A new research study is needed to model a dynamic Ross Ice Shelf with all its feeder ice streams, outlet glaciers, and ice calving dynamics in three dimensions over time to fully test our hypothesis. The required model must allow accelerated calving if further warming melts sea ice and discerps the ice shelf. Calving must then successively pull the outlet glacier “nails” so collapse of the marine West Antarctic Ice Sheet proceeds to completion.

show abstract

Fracture and back stress along the Byrd Glacier flowband on the Ross Ice Shelf

Cited by 9 publications

References 19 publications

Creep deformation and buttressing capacity of damaged ice shelves: theory and application to Larsen C ice shelf

Creep deformation and buttressing capacity of damaged ice shelves: theory and application to Larsen C ice shelf

Multidecadal Basal Melt Rates and Structure of the Ross Ice Shelf, Antarctica, Using Airborne Ice Penetrating Radar

Instability of the Antarctic Ross Sea Embayment as climate warms

Contact Info

Product

Resources

About