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HomeSpits­ber­gen infor­ma­ti­on → Drift ice, pack ice, fjord ice

Drift ice, pack ice and fjord ice in Spitsbergen

To start with, we have to defi­ne what we are tal­king about. You can call any kind of floa­ting ice drift ice. This inclu­des ice­bergs, which is land-bor­ne ice, deri­ved from gla­ciers. In a stric­ter sen­se, we think of fro­zen sea­wa­ter when we are tal­king about drift ice. Ice floes, more or less flat. In case the­se ice floes are pushed tog­e­ther by wind and cur­r­ents, hard­ly lea­ving open water bet­ween them, you have pack ice.

Ice chart, Spitsbergen

The ice chart of the Sval­bard area, 28 novem­ber 2014, shows a typi­cal drift ice dis­tri­bu­ti­on with a lot of ice in the east (actual­ly, more than usu­al in novem­ber) and an open west coast. The ocea­nic cur­r­ents con­trol this typi­cal pat­tern. © Nor­we­gi­an meteo­ro­lo­gi­cal insti­tu­te, avail­ab­le via Polar­view.

The drift ice dis­tri­bu­ti­on in Spits­ber­gen is con­trol­led by two ocea­nic cur­r­ents: the West Spits­ber­gen Cur­rent keeps the west coast and, to a vary­ing degree, the north coast ice free, while the col­der East Spits­ber­gen Cur­rent brings a lot of drift ice from the Arc­tic Oce­an to eas­tern Sval­bard. The cen­tral west coast (Kongsfjord, Isfjord) is most­ly acces­si­ble for smal­ler ships more or less year round; the inner bran­ches are usual­ly fro­zen, though. On the north coast, it chan­ces from year to year. In some years, the who­le north coast to Ams­ter­damøya in the west is blo­cked with den­se drift ice. In other years, Sjuøya­ne or even Kvi­tøya are acces­si­ble in late June or ear­ly July. On the con­tra­ry, in 2014 the eas­tern part of Nord­aus­t­land did not beco­me ice free at all.

The cur­rent that is slow­ly moving sou­thwards on the eas­tern side of the archi­pe­la­go brings a lot of drift ice well into the sum­mer. The cur­rent is going around the south cape (Sør­kapp) of Spits­ber­gen, then taking a nort­her­ly cour­se again, fol­lowing the sou­thern west coast. As a result, the sou­thern fjords like Horn­sund and some­ti­mes even Bellsund are often blo­cked by ice in the ear­ly sum­mer, when the west coast fur­ther north is ice free. Some drift ice fiel­ds can drift fur­ther north and move around in Isfjord in July, but that does not hap­pen too often.

drift ice, southeastern Svalbard

Drift ice, sou­the­as­tern Sval­bard, near Edgeøya.

Des­pi­te of the­se strong fluc­tua­tions from year to year, the cur­rent long-term trend is qui­te clear. It is now much easier to reach remo­te islands in nor­the­as­tern Sval­bard that used to be in ice most of the time as recent­ly as 20 or even 10 years ago. In 2000, tour ope­ra­tors did not sche­du­le cir­cum­na­vi­ga­ti­ons ear­lier than mid July. By now, it is com­mon to attempt cir­cum­na­vi­ga­ti­ons in ear­ly July or even to start in late June, and chan­ces for suc­cess are not that bad at all. Sci­en­ti­fic data sup­port this expe­ri­ence. Both the spa­ti­al and sea­so­nal extent of sea ice and the average ice thic­kness have decre­a­sed. Whe­re­as ice floes used to be 1.20 m thick in the Spits­ber­gen area in the past, they are rather near 0.80 m now.

Ice is, howe­ver, much thi­c­ker whe­re­ver it is pushed tog­e­ther. Edges of ice floes pushed up abo­ve each other form so-cal­led pres­su­re ice rid­ges or just pres­su­re rid­ges. The­se rid­ges are long, but rather nar­row rid­ges of chao­tic ice blocks and frag­ments of floes that can be several metres high, 12-15 m and even more have been obser­ved in the Arc­tic Oce­an, whe­re huge mas­ses of ice are being moved around and against each other by cur­r­ents and winds without any pro­tec­tion of land. Such migh­ty pres­su­re ice rid­ges have iso­sta­tic roots. In other words, they don’t just pro­tru­de up into the air, but also down into the water.

pressure ice ridge, Storfjord

Pres­su­re ice ridge, Storfjord, off Spitsbergen’s east coast.

Fjord ice does not count as drift ice. It is also cal­led fast ice, as it is in firm con­nec­tion with near­by shores insi­de a fjord or small bay. It does not move hori­zont­al­ly at all, but it does move ver­ti­cal­ly with the tides, resul­ting in tidal cracks whe­re the ice meets the shore. On calm days, you may here the ice moving near the tidal cracks. Fjord ice is rela­tively flat. The smal­ler fjords in Spitsbergen’s west coast fjord sys­tems used to free­ze over regu­lar­ly in the past, but are less reli­able now. Advent­fjord has not been firm­ly fro­zen for several years now (late 2014), and Tem­pel­fjord did not have a fast ice cover as good as it used to be in the past in 2014. The loss of fjord ice is bad for wild­life such as Rin­ged seals, which need ice to give birth and to rest.

Fjord ice, Tempelfjord

Solid fjord ice, Tem­pel­fjord. Ear­ly May Mai 2013.

The big Isfjord used to free­ze over qui­te fre­quent­ly in the ear­ly 20th cen­tu­ry, but it has never been fro­zen every year in his­to­ri­cal times. It is known to have fro­zen over after 2000, but not in recent years.

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last modification: 2019-02-25 · copyright: Rolf Stange
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