Tag Archives: habitat

New polar bear hunting habitat forming already along the coast of the Laptev Sea: A new trend?

Not even three weeks after the yearly minimum of sea ice extent was reached this year, new shorefast ice is already forming off the coast of Siberia, which is critical fall hunting habitat for polar bears.

Polar bears on a seal kill in new ice, 31 October 2020 in W. Hudson Bay via webcam.

So, not only was this year’s sea ice extent for September at the very lowest extreme of predicted levels for late summer, given ever-increasing CO2 concentrations in the atmosphere, new ice seems to be forming earlier in the fall as well, which bodes well for winter ice formation. It’s looking to me like the decade-long increasing trend of September ice extent since 2012 (see below) may indicate a change more biologically relevant to ice-dependent Arctic animals than the zero trend since 2007.

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Sea ice average for March is the metric used to compare to previous winters

The average sea ice cover at the end of March is the metric used to compare ‘winter’ ice to previous years or decades, not the single-day date of ‘most’ ice. This year, March ended with 14.6 mkm2 of sea ice, most of which (but not all) is critical polar bear habitat. Ice charts showing this are below.

But note that ice over Hudson Bay, which is an almost-enclosed sea used by thousands of polar bears at this time of year, tends to continue to thicken from March into May: these two charts for 2020 show medium green becoming dark green, indicating ice >1.2 m thick, even as some areas of open water appear.

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Arctic sea ice maximum extent was present for at least two weeks at about 14.9 million km2

US National Snow and Ice Data Center says the Arctic maximum extent for this winter peaked at 14.88 mkm2 on 25 February, but in fact this amount of ice coverage lasted for at least two weeks (22 February – 8 March), with very slight variation. Just a little something they all left out of their announcements, for some reason.

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Mid-winter polar bear sea ice habitat is abundant & within range of long-term average

Ahead of International Polar Bear Day (27 February) this year, polar bear habitat is as abundant as it has been for decades. This is a tough time for polar bears, many of which will be finding it hard to find seals to eat, as newborn seals won’t be an available food resource for about a month in most areas. Thin and hungry bears are dangerous.

Sea ice charts below for the Arctic as a whole and by region.

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Late freeze-up for W. Hudson Bay polar bears at odds with ice conditions elsewhere

Sea ice is finally starting to form along the western shore of Hudson Bay, lagging well behind ice formation in the rest of the Arctic. Oddly, however, last year it was just the opposite: some WH bears were able to start hunting as early as 31 October (see photo below) while ice formation lagged behind in the Chukchi and Barents Seas.

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Polar bear habitat in Canada at the first week of June sees widening of critical polynyas

Winds primarily cause the apparent sea ice ‘breakup’ in late spring through the widening of persistent polynyas and shore leads. This year the development of critical open water areas in Canada (which are important feeding areas for polar bears) is on track with previous years in most areas, although there is a lot of year-to-year variability.

Several prominent polynas also opened up along the Russian coast and Northeast Greenland: see the entire Arctic condition at 7 June 2021 below, courtesy NSIDC:

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Polar bear habitat update for late November

Sea ice formation is ahead of usual in some regions and behind in others but overall, sea ice habitat is abundant enough for this time of year for virtually all polar bears across the Arctic to be back out on the sea ice hunting seals.

Overall, there was more sea ice at 24 November 2020 than there was on the same date in 2016, which was the last year that a number of polar bear subpopulations were surveyed, including Western and Southern Hudson Bay, Southern Beaufort, Chukchi Sea (Crockford 2019, 2020), see graph below from NSIDC Masie:

Northern Hemisphere sea ice at 24 November, 2016-2020.

UPDATE 27 November 2020: Problem bear report published today (for week 13, Nov. 16-22) has been added below.

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Amid crying over low Arctic ice, W Hudson Bay polar bears leave ice as late as 2009

This year, the last collared Western Hudson Bay polar bear to leave the ice left as late, or later, than the last collared bear did in 2009 (which was an unusually late breakup year) and so far, all bears spotted have been in good physical condition despite inhabiting one of the most southern regions of the Arctic. All the while, sea ice experts have been hand-wringing about low Arctic sea ice –– in general and as polar bear habitat.

Polar bear Cape East 0 Wakusp NP _24 Aug 2020 earlier

A female with two yearling cubs on the shore of Wakusp National Park, Western Hudson Bay on 24 August 2020. Taken via livecam from almost a mile away.

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Winter sea ice maximum extent on March 5 was the highest since 2013

The most positive thing that US National Snow and Ice Data Center sea ice experts could say about this year’s winter sea ice maximum was that it wasn’t a record breaker. But it provides ample polar bear habitat when the bears need it most: just before the critical spring feeding season.

Sea ice extent 2020 March 5_sea ice maximum called_15 point 05 mkm2 NSIDC 24 March

In fact, they said: “The 2020 maximum sea ice extent is the eleventh lowest in the 42-year satellite record, but the highest since 2013.”  All that winter ice is essential polar bear habitat just before the critical spring feeding season (Crockford 2019, 2020) and it’s one of the reasons that polar bears are thriving.

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Polar bear sea ice habitat at the start of the Arctic winter is abundant except off Labrador

After a bit of ineffectual hand-wringing from polar bear specialists about low summer and fall sea ice conditions and unsubstantiated worries about impacts on bear survival – including Southern Beaufort Sea, Chukchi Sea and Hudson Bay  – I’ve heard no concerns expressed so far about the unusually low extent of ice off the East Coast of North America at the start of this winter. The Labrador Coast is just about the only region bereft of ice this winter but could catch up quickly at any time: ice coverage in the Barents Sea, East Greenland, and Bering Sea is similar to or above recent levels (last five years) so far, as is the overall extent.

masie_all_zoom_4km 2020 Jan 2

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