Polar bear habitat update at mid-June: more than enough for survival

Here we are at the middle of June, when most polar bears are pretty much done with hunting seals for the season. And despite hand-wringing from some quarters, sea ice extent is down only marginally from average at this time of year and certainly not enough to impact polar bear survival.

Polar_bear Bering Sea 2007 USFWS lg

Given the large expanse of open water in the Southern Beaufort so early in the season, one resident pessimist insists those polar bears are “challenged” by the lack of ice. If he is right, there should be reports of dozens upon dozens of skinny and dying bears along the coast of Alaska this summer. If not, he will pretend he never suggested any such thing.

So far, despite the early loss of ice in some regions, there have been no reports of polar bears ashore unusually early. Hudson Bay still has lots of thick first year ice, so despite the overall reduced Arctic ice coverage, none of the three Hudson Bay polar bear populations are facing the earlier-than-usual sea ice breakup this year as we keep being promised will show up. In fact, there hasn’t been a significantly early breakup in Western Hudson Bay since 2010 (see previous posts here and here).

Arctic in General

From NISDC at 13 June, 2019 (gold) compared to 2012 (dashed line) and 2018 (blue):

Sea ice extent 2018 and 2012 vs 2019 at 13 June_NSIDC interactive

From NSIDC Masie at 13 June 2019:

masie_all_zoom_4km 2019 June 13

Compare above to 2017:

masie_all_zoom_4km 2017 June 13

Canada (home to about half the worlds polar bears)

Sea ice in Canada on 14 June 2019, with abundant ice everywhere except the coast of Labrador in the east and the Southern Beaufort in the west:

Sea ice Canada 2019 Jun 14

Compare the above to 2017 on the same date:

Sea ice extent Canada 2017 June 14

Beaufort Sea

‘Departure from normal’ chart from Canadian Ice Service below shows a lot of red (less than average) for the week of 10 June 2019, indicating lots of open water:

Western Arctic weekly departure from normal 2019 June 10

Looks bad, right? However, what ice that is left is primarily thick first year ice (dark green, >1 m thick) or metres-thick multi-year ice (brown), with solid patches of it along the shore (i.e. shore-fast ice). Keep in mind that ice edges are where seals congregate, so that’s where most bears hang out at this time of year:

Western Arctic weekly stage of development 2019 June 10

Polar bear specialist Andrew Derocher over the last week or so:

Hudson Bay

Hudson Bay weekly departure from normal 2019 June 10

All of the dark green in the chart below is thick first year ice >1 metre in thickness (light green is thinner ice and blue is open water):

Hudson Bay weekly stage of development 2019 June 10

Compare the above to 2010 for the same week (an early breakup year):

Hudson Bay weekly stage of development 2010_June 14

Barents Sea

More or less average levels of ice in the Barents Sea this spring:

Svalbard ice extent 2019 June 14 graph_NIS

And this is what it looks like on a map:

Barents Sea ice extent 2019 June 14_NIS

Looking across the top of the Arctic (below, for Day 164 or 13 June 2019, via NSIDC Masie), we see more ice than in recent years in the east (Barents/Kara Seas) and less in the Chukchi Sea, but all in all, no major catastrophe for polar bears. Some will come ashore shortly for the summer fast while most will take to the ice: it’s what they have always had the ability to do. Bears that have feed well over the spring do not require sea ice to survive over the summer.

Sea ice Bering to Barents Seas June 13_MASIE

Bottom line:

Book graphic 3 with bear for promotion

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