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Daily Archives: 6. October 2020 − News & Stories

Isfjord is a high-arc­tic fjord again. For a while.

Less and thin­ner ice in the inner­most bran­ches of Isfjord such as Tem­pel­fjord and Bil­lefjord, and a solid ice-cover in the wide, cen­tral parts of Isfjord pro­per not­hing but a remo­te dream – that has been the rea­li­ty in Spitsbergen’s lar­gest fjord in recent years, which does hard­ly live up to its name, “Ice fjord”, any­mo­re. Con­side­ring ocea­no­gra­phi­cal and bio­lo­gi­al cha­rac­te­ristics, Isfjord has not real­ly been a high-arc­tic fjord any­mo­re, but rather a sub-arc­tic one.

Bluewhale, Isfjord

Isfjord has deve­lo­ped a sub-arc­tic ocea­no­gra­phi­cal cha­rac­ter in recent years,
some­thing that has invol­ved, for exam­p­le, more wha­le sightin­gs.
The pho­to shows a blue wha­le in Isfjord in Sep­tem­ber 2018.

This may curr­ent­ly be chan­ging again – not per­ma­nent­ly, howe­ver, but at least for a while. This is the result of ocea­no­gra­phi­cal data that have recent­ly been gathe­red by a team of UNIS sci­en­tists. The data are part of a long-term pro­ject to moni­tor the deve­lo­p­ment in Isfjord. Frank Niel­sen, pro­fes­sor for ocea­no­gra­phy at UNIS, and his team have now published a report in Sval­bard­pos­ten.

A key result is that the­re is curr­ent­ly much less mild, salt-rich Atlan­tic water in Isfjord than in pre­vious years and the remai­ning volu­me of this water is lar­ge­ly at depths below 150 met­res. In recent years, mild Atlan­tic water that drifts north with the Gulf Stream and rea­ches Spitsbergen’s west coast, whe­re it is cal­led the West Spits­ber­gen cur­rent, has had an incre­asing­ly strong influence in the fjords on the west coast. The­se have, as a con­se­quence, lost much of their high-arc­tic cha­rac­ter in terms of ocea­no­gra­phy and bio­di­ver­si­ty, rather beco­ming sub-arc­tic fjords ins­tead. Important indi­ca­tors include water tem­pe­ra­tures, salt con­cen­tra­ti­ons and spe­ci­es com­po­si­ti­on, espe­ci­al­ly of zoo­plank­ton.


In the inner­most bran­ches, such as Petu­ni­abuk­ta (pic­tu­red here),
Isfjord’s high-arc­tic cha­rac­ter has been retai­ned so far.

Recent cli­ma­tic chan­ges have led to this deve­lo­p­ment: part of the com­plex pic­tures are chan­ged rou­tes of low pres­su­res, which now move north bet­ween Green­land and Spits­ber­gen, rather than moving east over the Barents Sea. The new rou­te of the low pres­su­res tends to push Atlan­tic water north and into Spitsbergen’s west coast fjords – an effect that can last over years, even though the low pres­su­res dis­ap­pear after a few days.

This year, howe­ver, regio­nal wea­ther pat­terns have been more like what they used to be in the past, with a more sta­ble nor­t­her­ly influence which has, noti­ce­ab­ly, led to few warm air incur­si­ons with mel­ting tem­pe­ra­tures in the win­ter, some­thing that had beco­me more com­mon in the years befo­re. Ano­ther result of the cur­rent air flow pat­tern in this sec­tor of the Arc­tic is the less pro­no­un­ced influence of tem­pe­ra­te water mas­ses in Spitsbergen’s fjords on the west coast. Other reasons for this cur­rent deve­lo­p­ment may include the strong mel­ting of local gla­ciers in the very warm wea­ther of the last sum­mer, which has led to a hig­her input of cold freshwa­ter to the top lay­er of the fjord.

All this has now led to a chan­ge of spe­ci­es-com­po­si­ti­on of zoo­plank­ton back to a more high-arc­tic mix­tu­re. Arc­tic zoo­plank­ton is lar­ge­ly domi­na­ted by cope­pods. In recent years, the sub-arc­tic spe­ci­es Cala­nus fin­mar­chi­cus has beco­me domi­nant in most parts of Isfjord, but now it is main­ly the high-arc­tic spe­ci­es Cala­nus gla­cia­lis that is domi­nant again.

Outer Isfjord

Curr­ent­ly, also cen­tral parts of Isfjord have a high-arc­tic ocea­no­gra­phi­cal cha­rac­ter again.

If this deve­lo­p­ment is not soon ter­mi­na­ted by strong low pres­su­res asso­cia­ted with hea­vy storms from the “wrong” direc­tion, then one of the results could be an ice cover that is more exten­si­ve and stron­ger than seen in recent years. Ano­ther result, if it lasts for a while, may be fewer wha­les and less cod in Isfjord next year.

But in case anyo­ne is struck by the thought that cli­ma­te chan­ge in the Arc­tic is cal­led off now: this is not the case. As Nil­sen puts it in his artic­le, it is not a sta­ble situa­ti­on, but “rather a local dead-cat boun­ce within a warm­ing Arc­tic” (ori­gi­nal quo­te: Men en sta­bil situas­jon er det ikke, det er mer som en lokal kram­pet­re­k­ning i et Ark­tis under oppv­ar­ming).


News-Listing live generated at 2024/July/14 at 02:42:08 Uhr (GMT+1)