Ice shove
![](https://upload.wikimedia.org/wikipedia/commons/thumb/2/2c/Ice_Shove.jpg/220px-Ice_Shove.jpg)
![](https://upload.wikimedia.org/wikipedia/commons/thumb/1/11/Ice_Shove_Wisconsin.jpg/220px-Ice_Shove_Wisconsin.jpg)
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Anice shove(also known asfast ice,anice surge,ice push,ice heave,shoreline ice pileup,ice piling, ice thrust,ice tsunami,[1]ice ride-up,orivuinIñupiat) is a surge of ice from an ocean or large lake onto theshore.[2] Ice shoves are caused byocean currents,strong winds, or temperature differences pushing ice onto the shore,[3] creating piles up to 12 metres (40 feet) high. Ice shoves can be caused by temperature fluctuations, wind action, or changing water levels[3]and can cause devastation to coastal Arctic communities. Cyclical climate change will also play a role in the formation and frequency of ice shove events; a rise in global temperatures leads to more open water to facilitate ice movement. Low pressure systems will destabilize ice sheets and send them shoreward.[1]Also referred to as "landfast ice", it is an essential component to the coastal sea ice system, including the sediment dynamics.Arcticpeoples utilize these ice shoves to travel and hunt.Ringed seals,an important prey for polar bears, are specifically adapted to maintain breathing holes in ice shoves, which lack the same openings usually used by marine mammals in drifting ice packs. The mere fact that the Ringed seal is uniquely adapted to utilizing ice shoves for breathing holes, and that polar bears have adapted to this behaviour for hunting, as well as the fact that the Iñupiat have a distinct term for the phenomena, indicates that ice shoves are a regular and continuing phenomena in the Arctic.[4]
Causes
[edit]Temperature fluctuations
[edit]When temperatures decrease, ice contracts and forms stress fractures; water then seeps into these tension cracks and freezes. When temperatures rise, the ice sheet expands. This sequence of events occurs cyclically until the total ice sheet has expanded considerably. If this ice sheet is in contact with a shoreline, it can exert considerable force on the land, causing the displacement of shore material.[3]When temperature fluctuations are drastic enough, the ice sheet contraction pulls far enough from shore to form a lane of water; for example, a drop from 0 °C to -20 °C results in an 11% volume decrease of a 1.5-km ice sheet.[3]This lane of water subsequently freezes. When temperatures rise at sufficient rates (~1 °C/hr for upwards of 5 hours), the ice sheet expands onto land.[3]The physical composition of the ice itself is also important; ice that has formed from water-soaked snow, known as white ice, hinders the process of thermal ice expansion because itsalbedois higher than other forms of ice, resulting in lowerthermal conductivity.In order for conditions to facilitate thermal expansion of ice and in turn ice shoves, the ice needs to be susceptible to temperature change, making black ice more suitable for the formation of ice shoves.[3]
Wind action
[edit]Because land heats faster than ice and transfers heat to the adjacent ice, the ice nearest to the shore melts first when temperatures rise.[3]Water then exists between the ice sheet and the shoreline, facilitating the movement of ice sheets when wind acts on them. An open channel of water allows for reducedresistive forceson the ice sheet, increasing the likelihood that an ice shove event can occur.[1]The direction of the wind ultimately directs the motion of the ice shove. The effectiveness of wind as a driving force for ice movement relies on a multitude of factors including the size and shape of the body of water and wind strength. Large, wide-open bodies of water have a greater surface area for wind to act upon compared to smaller, sheltered bodies of water. Persistent, high-speed winds apply more force than slower wind gusts, making them optimal for driving ice sheets ashore.[3]
Fluctuating Water Levels
[edit]Falling water levels cause a bending force between ice that has already breached the shore and the ice floating immediately offshore. This bending force causes cracks in the ice where water can seep in and freeze. When water levels rise again, the ice experiencescompression forcesthat subsequently push it onto land. This mechanism is comparable to thethermal expansionprocess described above.[3]
Effects on arctic communities
[edit]Arctic communities can be affected by ice shoves. Ice shoves commonly occur along theChukchi Seaincluding inWainwright, AlaskaandBarrow,Alaska.[5]Studies have shown that the formation oflandfast iceis starting to form later and breakup earlier in theChukchiandBeaufort seas.More open water days increase the likelihood of destructive coastal events like ice shoves in these regions. Some have described them as 'icetsunamis',[6]but the phenomenon works like aniceberg.[7]Witnesses have described the shove's sound as being like that of atrainorthunder.[2][8][9][6]Ice shoves can damage buildings and plants that are near to the body of water.[2][6][8][9][10]
Arctic ice and climate change
[edit]![](https://upload.wikimedia.org/wikipedia/commons/thumb/7/7f/IceShoveClimateDiagram.pdf/page1-220px-IceShoveClimateDiagram.pdf.jpg)
As described above, ice shove events occur due to deformation of land-fast ice, ice that is anchored to the coast. Land-fast ice grows either locally or by merging withdrift ice.In the Arctic, theTranspolar Drift Streamand theBeaufort Gyreare mostly responsible for sea ice transport. In the Beaufort Gyre, surface ice transport is westward directed towards the Alaskan coast, hence being a driver in fast ice growth.[11]The last decades adecline in Arctic ice coverhas been observed.[12][13]Land-fast ice forms later and withdraws earlier, leading to more open water days. Open waters lead to longerwind fetch,which in turn produces more energetic waves near coastal zones, increasing fast ice erosion.[13][14]The loss of sea ice directly results in a lower surfacealbedoand thus higher Arctic temperatures.[1][14]These climate change related processes may lead to higher occurrence of ice shove events.
Ice shoves commonly occur in late autumn or early spring, when ice is relatively unstable due to higher temperatures.[1]They can also occur in mid-winter, as shown by the 2016 ice shove event atCape Espenberg,Alaska.[1]A stronglow-pressure arearesulted in favourable conditions for an ice shove. Ice shoves can still occur when there are ice-free summers in the Arctic, which studies suggest can happen occasionally as soon as 2050.[15]In the case of no future reduction ofcarbon dioxideemission it is suggested that ice-free Arctic winters are also possible,[15]potentially leading to a reduction of Arctic ice shove occurrences in those years. However, these temporal changes and their effect on ice shoves are still subject to discussion. This is namely highly dependent on the location and timing of ice-free conditions.
Ice shoves are not confined to just polar latitudes; they also occur in the highermid-latitudes.If a longer cold spell, which is often related to thepolar vortex,allows ice to grow locally in a larger body of water, followed by sudden warming and strong winds, ice shoves can appear in a similar fashion as in Arctic regions. Arctic sea ice decline is also linked to the slowdown of theAtlantic Meridional Overturning Circulation(AMOC) due to fresh water and temperature anomalies.[16]Due to complex ocean-atmosphere interactions, this can lead to higher storm activity in the mid-latitudes. This change could potentially give more favourable conditions for ice shove events to occur at mid-latitudes, though no research has been done on this subject.
See also
[edit]- Ice jacking– Structural damage caused by freezing water
- Frost heaving– Upwards swelling of soil during freezing
- Surge (glacier)– Event where a glacier can advance substantially
External links
[edit]References
[edit]- ^abcdefBogardus, Reyce; Maio, Christopher; Mason, Owen; Buzard, Richard; Mahoney, Andrew; de Wit, Cary (2020)."Mid-Winter Breakout of Landfast Sea Ice and Major Storm Leads to Significant Ice Push Event Along Chukchi Sea Coastline".Frontiers in Earth Science.8:344.Bibcode:2020FrEaS...8..344B.doi:10.3389/feart.2020.00344.ISSN2296-6463.
- ^abcDoran, Chad."Ice shoves cause damage on Lake Winnebago shoreline".WLUK-TV.Archived fromthe originalon January 26, 2013.RetrievedJanuary 21,2013.
- ^abcdefghiDionne, Jean-Claude (1979)."Ice action in the lacustrine environment. A review with particular reference to subarctic Quebec, Canada".Earth-Science Reviews.15(3): 185–212.Bibcode:1979ESRv...15..185D.doi:10.1016/0012-8252(79)90082-5.ISSN0012-8252.
- ^scholar.google
- ^Mahoney, Andrew; Eicken, Hajo; Shapiro, Lewis; Grenfell, Tom C. (2004)."Ice motion and driving forces during a spring ice shove on the Alaskan Chukchi coast".Journal of Glaciology.50(169): 195–207.Bibcode:2004JGlac..50..195M.doi:10.3189/172756504781830141.
- ^abcAll Things Considered (2013-04-24)."'Ice Shove' Damages Some Manitoba Homes Beyond Repair ".NPR.Retrieved2013-05-15.
- ^"'Ice tsunamis' sweep into homes ".CNN. 13 May 2013.Retrieved2013-05-15.
- ^ab"Winds whip up worry in Manitoba community hit by ice wall".CBC News.May 13, 2013.Retrieved2013-05-15.
- ^ab"Wall of ice destroys Manitoba homes, cottages".CBC News.May 11, 2013.Retrieved2013-05-15.
- ^"Ice Tsunami..Glacier like ice moving across Mille Lacs lake, damaging houses, Minnesota".YouTube.Archivedfrom the original on 2021-12-19.Retrieved2014-09-08.
- ^Weeks, W. F. (2010).On sea ice.W. D., III Hibler. Fairbanks: University of Alaska Press. p. 30.ISBN978-1-60223-101-6.OCLC643302511.
- ^Serreze, Mark C.; Meier, Walter N. (2019). "The Arctic's sea ice cover: trends, variability, predictability, and comparisons to the Antarctic".Annals of the New York Academy of Sciences.1436(1): 36–53.Bibcode:2019NYASA1436...36S.doi:10.1111/nyas.13856.ISSN1749-6632.PMID29806697.S2CID44077118.
- ^abFarquharson, L.M.; Mann, D.H.; Swanson, D.K.; Jones, B.M.; Buzard, R.M.; Jordan, J.W. (October 2018)."Temporal and spatial variability in coastline response to declining sea-ice in northwest Alaska".Marine Geology.404:71–83.Bibcode:2018MGeol.404...71F.doi:10.1016/j.margeo.2018.07.007.ISSN0025-3227.
- ^abAsplin, Matthew G.; Galley, Ryan; Barber, David G.; Prinsenberg, Simon (June 2016)."Fracture of summer perennial sea ice by ocean swell as a result of Arctic storms".Journal of Geophysical Research: Oceans.117(C6): n/a.doi:10.1029/2011jc007221.ISSN0148-0227.
- ^ab"Simulations suggest ice-free Arctic summers by 2050".ESA Climate Office.Retrieved2021-05-17.
- ^Sévellec, Florian; Fedorov, Alexey V.; Liu, Wei (2017-07-31)."Arctic sea-ice decline weakens the Atlantic Meridional Overturning Circulation".Nature Climate Change.7(8): 604–610.Bibcode:2017NatCC...7..604S.doi:10.1038/nclimate3353.ISSN1758-678X.