71:, a body of ice that moves under its own weight. They can move upwards of 1,000 metres (3,300 ft) a year, and can be up to 50 kilometres (31 mi) in width, and hundreds of kilometers in length. They tend to be about 2 km (1.2 mi) deep at the thickest, and constitute the majority of the ice that leaves the sheet. In Antarctica, the ice streams account for approximately 90% of the sheet's mass loss per year, and approximately 50% of the mass loss in Greenland.
95:, which causes an increase in sheet discharge. Another factor causing ice streams to be found in low regions is that thicker ice results in faster velocity. As the thicker an ice stream is, the greater the driving stress at the bed, and thus the greater the velocity. In addition to driving stress, ice streams have better insulation as the thickness of ice increases, due to it retaining higher temperatures better, it can increase the rate of deformation, as well as
344:. As ice streams drain into the surrounding ocean, not only does this increase the sea level due to displacement of the ice runoff, but also by increasing the volumetric content of the oceans themselves, but this is almost negligible. As ice streams diminish in size, the pressure they exert on surrounding features like glaciers reduces, allowing the glacier that feeds into the sea to speed up and discharge more quickly,
33:
41:
20:
335:
as the stream carves through the underlain material, eroding it and pushing sediment into the water beneath the ice stream and through the drainage system. These low topographic areas can be up to a few kilometers in depth, and up to hundreds of kilometers in length. The resulting low regions act as
74:
The shear forces cause deformation and recrystallization that drive the movement, this movement then causes topographic lows and valleys to form after all of the material in the ice sheet has been discharged. Sediment also plays an important role in flow velocity; the softer and more easily deformed
352:
in the regions directly affected by the ice stream in question. As a result of this rise in sea level, albeit slow and almost minute in short scales but large over longer scales, the landscape will be altered. Rising sea levels will weather the surrounding sheet and cause erosion and deformation of
135:
and deforms it. Flow velocity of the ice stream is not entirely constant, but in short time scales of days to weeks, it can be treated as such, over long scales, however, it is variable, depending on how the conditions of thickness, temperature, water accumulation, stresses, and base material have
24:
21:
123:, it will be incapable of supporting the shear stress the ice stream places on the bed. The best type of sediment for increased speed of drainage is soft, deformable sediment, that allows the ice stream to flow over the combination of sediment and
23:
339:
Another problem arises from the discharge of the sheet through ice streams, which can be one of many factors causing small stage sheet collapse. In addition to this collapse, ice streams also act to increase the global
99:
sliding. As a substance's volume increases, it requires more energy per unit volume to raise its temperature, which is one of the reasons why it is so difficult for oceans to freeze or evaporate. Water is also a poor
184:
has many ice streams that carry billions of tons of ice to the sea a year. The Pine Island and
Thwaites streams have the highest amount of net discharge in west Antarctica while Lambert Glacier leads the way in
827:
Franke, Steven; Bons, Paul D.; Westhoff, Julien; Weikusat, Ilka; Binder, Tobias; Streng, Kyra; Steinhage, Daniel; Helm, Veit; Eisen, Olaf; Paden, John D.; Eagles, Graeme; Jansen, Daniela (5 December 2022).
287:
balances the driving stress for several hundred kilometers in the center of the ice stream. Further upstream, the initiation of the ice stream (established by looking at velocity data) is caused by a weak
228:(LGM). Analysis of landforms diagnostic of paleo-ice streams, revealed considerable asynchronicity in individual ice stream retreat histories. This notion is important when considering how the underlying
22:
75:
the sediment present, the easier it is for flow velocity to be higher. Most ice streams contain a layer of water at the bottom, which lubricates flow and acts to increase speed.
268:. With significantly more surface melt, only 50% of ice mass is lost through ice streams in Greenland, but they still are one of the primary modes of ice loss. the
758:
Larsen, Nicolaj K.; Levy, Laura B.; Carlson, Anders E.; Buizert, Christo; Olsen, Jesper; Strunk, Astrid; Bjørk, Anders A.; Skov, Daniel S. (14 May 2018).
308:
there are three main icefields - the North
Patagonian Icefield, South Patagonian Icefield, and Cordillera Darwin Icefield that all exhibit ice streams.
104:
of heat, so increased thickness will not only increase the amount of heat that can be retained, but also make more energy required for heat to be lost.
336:
a new drainage system for the ice sheet, as it allows movement of material through topographic low to increase, since the stream has left the sheet.
87:, surrounded by slower moving, higher topography ice sheets. The low topography arises as a result of various factors, the most prominent being that
276:
Earlier in the
Holocene, the ice stream system of northeast Greenland reached much farther into Greenland's interior compared to the present day.
953:
131:. If the underlying surface is bedrock, and not made of sediments, the speed will decrease. The bedrock acts to slow down the ice stream as it
703:
Livingstone, Stephen J.; Ó Cofaigh, Colm; Stokes, Chris R.; Hillenbrand, Claus-Dieter; Vieli, Andreas; Jamieson, Stewart S. R. (2012-02-01).
877:
189:. The rate at which the Antarctic ice sheet is losing mass is accelerating and the past and ongoing acceleration of ice streams and outlet
926:
232:
of ice streams control at what rate and how they retreat. Furthermore, this reinforces the importance of internal factors such as
193:
is considered to be a significant, if not the dominant cause of this recent imbalance. Ice streams hold serious implications for
311:
Ice streams are also important for ice sheet dynamics of
Iceland's ice fields. In Iceland, areas with reticulated ridges, ribbed
300:
Ice streams can also occur in ice fields that are significantly smaller than the
Antarctic and Greenland ice sheets. In the
36:
Velocity map of
Antarctica. Ice streams can be seen with increasing speeds (blue-yellow-white) flowing toward the coast.
331:
after an ice stream has been completely drained from the ice sheet itself. The topographic lows are formed by glacial
269:
370:
Bamber J.L.; Vaughan D.G.; Joughin I. (2000). "Widespread complex flow in the interior of the
Antarctic Ice Sheet".
573:
Rignot, E.; Bamber, J. L.; Van Den Broeke, M. R.; Davis, C.; Li, Y.; Van De Berg, W. J.; Van
Meijgaard, E. (2008).
489:
145:
323:
Ice streams have various impacts on the surrounding event. The most obvious one is the development of large
91:
accumulates at topographic lows. As water accumulates, its presence increases basal sliding and therefore
871:
Joughin, Ian; Fahnestock, Mark; MacAyeal, Doug; Bamber, Jonathan L.; Gogineni, Prasad (1 December 2001).
272:
Ice Stream, at 600 km (370 mi) long, drains roughly 12% of the entire ice sheet through three
704:
315:, and trunk-flow zones have demonstrated no control over the direction and magnitude of ice streams.
48:
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ice streams of West
Antarctica with fast flow and a weak bed with low driving stresses. The basal
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play a key role in the rate at which ice streams drain. If the underlying sediment is too
8:
575:"Recent Antarctic ice mass loss from radar interferometry and regional climate modelling"
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830:"Holocene ice-stream shutdown and drainage basin reconfiguration in northeast Greenland"
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Proceedings of the Royal
Society A: Mathematical, Physical and Engineering Sciences
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178:(84 billion long tons; 94 billion short tons) per year measured in 2006.
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Glaciers are currently the most out of balance, with a total net mass loss of 85
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645:"History, mass loss, structure, and dynamic behavior of the Antarctic Ice Sheet"
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760:"Instability of the Northeast Greenland Ice Stream over the last 45,000 years"
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troughs indicate where paleo-ice streams in Antarctica extended during the
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873:"Observation and analysis of ice flow in the largest Greenland ice stream"
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973:"Quick Facts on Ice Shelves | National Snow and Ice Data Center"
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Fits and Starts – What regulates the flow of huge ice streams?
428:"Geomorphology under ice streams: Moving from form to process"
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the sheet itself, thus altering the landscape and morphology.
237:
208:
has increased by 59% in the past 10 years and by 140% in the
175:
154:
is drained to the sea by several ice streams. The largest in
88:
279:
The northeast Greenland ice stream behaves similarly to the
124:
826:
513:
Kyrke-Smith, T. M; Katz, R. F; Fowler, A. C (2014-01-08).
220:
that comes off an ice sheet. Geomorphic features such as
757:
515:"Subglacial hydrology and the formation of ice streams"
197:
as 90% of Antarctica's ice mass is lost through them.
28:
These animations show the motion of ice in Antarctica.
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348:This rise in sea level affects both topography and
568:
566:
1008:
83:Ice streams are typically found in areas of low
16:A region of fast-moving ice within an ice sheet
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107:In addition to thickness, water, and stresses,
878:Journal of Geophysical Research: Atmospheres
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216:mass budget as they dictate the amount of
898:
855:
803:
785:
643:Bell, Robin E.; Seroussi, Helene (2020).
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244:size in determining ice stream dynamics.
39:
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954:"Lund University Department of Geology"
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47:image of ice streams flowing into the
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212:. Ice streams control much of the
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204:is generally stable, ice loss in
927:"The Patagonian Icefields today"
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820:
729:10.1016/j.earscirev.2011.10.003
488:Davies, Bethan (22 June 2020).
925:Bendle, Jacob (22 June 2020).
751:
705:"Antarctic palaeo-ice streams"
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1:
394:10.1126/science.287.5456.1248
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146:List of Antarctic ice streams
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252:Ice streams that drain the
127:, while supporting against
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857:10.1038/s41561-022-01082-2
787:10.1038/s41467-018-04312-7
143:
426:Stokes, Chris R. (2018).
49:Filchner-Ronne Ice Shelf
669:10.1126/science.aaz5489
266:Kangerdlugssuaq Glacier
531:10.1098/rspa.2013.0494
52:
37:
29:
931:AntarcticGlaciers.org
765:Nature Communications
709:Earth-Science Reviews
494:AntarcticGlaciers.org
256:into the sea include
43:
35:
27:
900:10.1029/2001JD900087
885:(D24): 34021–34034.
226:Last Glacial Maximum
891:2001JGR...10634021J
848:2022NatGe..15..995F
778:2018NatCo...9.1872L
721:2012ESRv..111...90L
661:2020Sci...367.1321B
655:(6484): 1321–1325.
626:"Nature Geoscience"
593:2008NatGe...1..106R
444:2018ESPL...43...85S
386:2000Sci...287.1248B
380:(5456): 1248–1250.
304:region of southern
270:Northeast Greenland
254:Greenland ice sheet
210:Antarctic peninsula
152:Antarctic Ice Sheet
67:. It is a type of
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835:Nature Geoscience
580:Nature Geoscience
346:rising sea level.
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160:Lambert Glacier
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59:is a region of
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1017:Ice streams
772:(1): 1872.
325:topographic
222:bathymetric
168:Pine Island
1011:Categories
982:2020-11-25
936:2020-11-22
587:(2): 106.
499:2020-11-25
357:References
350:bathymetry
302:Patagonian
182:Antarctica
176:gigatonnes
166:the large
144:See also:
140:Antarctica
85:topography
63:within an
57:ice stream
977:nsidc.org
909:2156-2202
796:2041-1723
745:129048010
737:0012-8252
685:213191762
539:1364-5021
462:1096-9837
342:sea level
327:lows and
248:Greenland
218:discharge
214:ice sheet
136:changed.
121:saturated
102:conductor
79:Mechanics
65:ice sheet
1027:Glaciers
814:29760384
677:32193319
557:24399921
525:(2161).
402:10678828
313:moraines
191:glaciers
172:Thwaites
109:sediment
93:velocity
45:Radarsat
887:Bibcode
844:Bibcode
805:5951810
774:Bibcode
717:Bibcode
657:Bibcode
649:Science
589:Bibcode
548:3857858
440:Bibcode
382:Bibcode
373:Science
333:erosion
329:valleys
133:incises
113:bedrock
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