Sea ice soften within the Arctic Basin leaves an space for polar bears bigger than Greenland

Reposted from Dr. Susan Crockford’s Polar Bear Science

Posted on August 29, 2019

Sea ice soften within the Arctic Basin leaves an space for polar bears bigger than Greenland

Most polar bears that spend the spring feeding within the peripheral seas of the Arctic Basin (such because the Beaufort, Chukchi, Kara, and Barents Seas) stay on the persistent pack ice of the central Arctic in the course of the summer season and this August, that refugium continues to be bigger than Greenland. Most of those bears don’t use this July-September Arctic Basin ice as a searching platform except they’re very fortunate: the few seals obtainable are arduous to catch. For essentially the most half, polar bears quick or eat little or no in the course of the summer season whether or not they’re on land or on ice (see references on this publish).

Since early June, sea ice consultants have been wringing their palms over the melting of Arctic sea ice and providing breathless hypothesis that this yr’s September minimal could possibly be – gasp! – as little as or lower than 2012 and even much less. However now, because the graph of ice cowl at 28 August reveals beneath, that final result is wanting not simply unlikely however nearly unimaginable (the blue line is 2019 extent, purple dashed line is 2012, and the brown line is 2016):

As anticipated, the failure of the ice to stay on observe to set a brand new document September low resulting from world warming is shrugged off with a reminder that summer season ice extent “is delicate to adjustments in day by day climate situations.”

Arctic Basin

In accordance with NSIDC Masie ice charts proven beneath, there may be precisely the identical quantity of ice within the Arctic Basin this yr on the finish of August – three.zero mkm2 – as there was in 2012: it was simply distributed a bit otherwise. This makes the standard summer season refugium for a lot of polar bears bigger in space than all of Greenland, which is simply about 2.17 mkm2. That’s loads of area for 1000’s of bears to hang around for a number of months.

Sea ice within the Arctic Basin at 26 August 2019 (three.zero mkm2):

Sea ice within the Arctic Basin at 26 August 2012 (three.zero mkm2):

At 26 August 2019, sea ice was nonetheless current within the peripheral seas: packed into the Canadian Arctic Archipelago, off northeast Greenland and the northern Barents Sea in addition to the northern Laptev Sea. That is numerous ice for summering polar bears:

Barents Sea and Svalbard

In 2012, the Barents Sea was completely ice-free by late July but when the Svalbard polar bear inhabitants survey was accomplished in August 2015, the inhabitants had grown by 42% – this was apparently a non-statistically vital enhance however undoubtedly not a decline. Ongoing analysis reveals Svalbard bears are nonetheless thriving.

The low sea ice protection within the western Arctic since early summer season this yr has been greater than balanced out by the abundance of ice within the jap Arctic: ice loss within the Beaufort and Chukchi Seas early within the season was the Barents Sea’s achieve.

Barents Sea polar bears now have ice near shore this summer season but it surely stays to be seen if this can garner any benefit to their well being and survival in comparison with earlier years.

Final yr at the start of August (above), there was no ice wherever close to Svalbard however this yr simply days from the top of August (beneath) the northeast portion of Svalbard is surrounded by ice that’s 2 metres thick! Nonetheless, polar bears don’t want thick ice: half a metre of ice (i.e. 50 cm) is greater than sufficient to assist a full grown bear. We all know this as a result of within the fall, bears on land head out on ice when it’s about 30 cm thick.

Svalbard ice extent this yr is far greater than common:

Sea ice at Svalbard, 26 August 2019:

Examine above to 27 August 2012 (beneath):

Polar bear specialist Andrew Derocher claims that numerous ice this yr round Svalbard is nice information for polar bears however the proof from earlier years reveals that no ice round Svalbard on the peak of summer season has not been detrimental to their well being and survival (Aars 2018; Aars et al. 2017; Andersen et al. 2012; Crockford 2019a, b).

Canadian Arctic Archipelago

Much more than every week earlier in 2012 (beneath, the one picture I’ve is 19 Aug) the ice was largely clear by means of the jap method to the northern route of the Northwest Passage. By the top of August, one small boat had made it by means of that difficult northern passage, which seems extremely unlikely to be doable this yr for vessels apart from icebreakers.

Here’s a satellite tv for pc picture of the route printed by NASA on 2 August 2012, however be aware this caveat:

“In accordance with stories from the Canadian Ice Service, ice appeared to retreat shortly from Parry Channel in late July and early August 2012, however the channel was most likely not totally open. In some circumstances, sea ice will be skinny sufficient to flee detection by a satellite tv for pc sensor, however nonetheless be thick sufficient to hamper navigation.”

Northwest Passage routes:

The truth that the Royal Canadian Mounted Police schooner St. Roch was capable of transit the northern passage in the summertime of 1944 from east to west, encountering little ice for a lot of the center portion of the journey, is proof that ice-free situations in Parry Channel occurred naturally even earlier than world warming. An in depth account of the St. Roch voyages (a captivating learn with a map and many footage, from Canadian Geographic 1945) is offered right here in pdf format.

References

Aars, J. 2018. Inhabitants adjustments in polar bears: protected, however shortly shedding habitat. Fram Discussion board E-newsletter 2018. Fram Centre, Tromso. Obtain pdf right here (32 mb).

Aars, J., Marques,T.A, Lone, Okay., Anderson, M., Wiig, Ø., Fløystad, I.M.B., Hagen, S.B. and Buckland, S.T. 2017. The quantity and distribution of polar bears within the western Barents Sea. Polar Analysis 36:1. 1374125. doi:10.1080/17518369.2017.1374125

Andersen, M., Derocher, A.E., Wiig, Ø. and Aars, J. 2012. Polar bear (Ursus maritimus) maternity den distribution in Svalbard, Norway. Polar Biology 35:499-508.

Crockford, S.J. 2019a. State of the Polar Bear Report 2018. World Warming Coverage Basis Report 32, London. pdf right here.

Crockford, S.J. 2019b. The Polar Bear Disaster That By no means Occurred. World Warming Coverage Basis, London. Obtainable in paperback and e-book codecs.

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