Late fall polar bear habitat 2020 compared to some previous years

Reposted from Polar Bear Science

Posted on December 22, 2020 | 

It’s time to look at sea ice habitat at 15 December (Julian Day 350), now that virtually all bears except pregnant females throughout the Arctic are either out on the sea ice attempting to hunt for seals or hunkered down against the darkness.

As is usual at this time of year, the Canadian Archipelago, the Beaufort, East Siberian and Laptev Seas are well covered in ice (see regions on map below). As for the rest, despite what one polar bear specialist has implied there is no evidence that a slower-than-usual fall freeze-up in the other peripheral seas of the Arctic negatively affects polar bear health or survival.

In fact, because of the attractiveness of the ice edge for seals in the fall, as I discussed last month, it’s possible that the longer the ice edge persists in fall, the more successful polar bears will be in hunting seals – except those above the Arctic Circle where lack of daylight from early November may cause polar bears to hunker down and rest rather than try to hunt through the darkness. But we’ll never know for sure, because bears have never been studied at this time of year – experts simply make assumptions about what happens (e.g. Stirling and Oritsland 1995).

Sea ice thickness also varies year to year throughout the season but does not matter much to polar bears, who hunt most successfully in first year ice less than 2m in thickness, which comprises all of the regions currently purple in the ice thickness chart below.

HUDSON BAY

This year at mid-December, there was more ice than usual in central and southern Hudson Bay (below) and somewhat less than usual in the eastern portion.

However, the ice is forming so fast now that by 18 December there was hardly any open water remaing over Hudson Bay and the ice to the north was solidifying (below). Recall that a similar freeze-up pattern left a pod of a dozen or so killer whales stranded in mid-January 2013 and killed four others in 2016. Such ice-entrapment suggests that despite a ‘warming’ Arctic, freeze-up patterns would have to change very dramatically for Hudson Bay to be an attractive place for killer whales. A recent DFO report concluded:

Killer whale ice entrapments are almost always fatal and can wipe out entire family groups, with long-lasting demographic impacts. Ice entrapments could therefore slow Arctic killer whale range expansions, particularly in areas where killer whales that are unfamiliar with sea-ice patterns fail to exit prior to ice formation in winter.

Compare Hudson Bay weekly stage of development charts (below) for this year back to 2014, from the Canadian Ice Service archives. You’ll see that this year appears to have more extensive 1st year ice (light green, ca. 30-70 cm) than any other year (although last year had almost as much) and that 2016 was notable as being a very late freeze-up year:

Western Hudson Bay polar bears with collars or tags deployed by Andrew Derocher and his University of Alberta crew (below) are spread out over the ice of the bay (two on land are denning females), a number are on the thickest ice in the north but others are on thinner ice to the south and east:

BAFFIN BAY, FOXE BASIN, AND DAVIS STRAIT

Ice covereage in the Canadian Eastern Arctic at mid-December is about average this year, according to CIS charts – only a bit of red and pink indicating ‘below normal’ in the east (off of Greenland):

Pack ice has moved down from the north through Baffin Bay into Davis Strait (below) and will soon be off the coast of Labrador, which has somewhat less ice than usual this year at mid-December:

The ice off Labrador at this time is shorefast ice developing and thickening in place (below). As far as we know, few polar bears summer on the northern Labrador coast, so this late ice development is unlikely to affect local bears. However, pack ice will move down during January and February until it engulfs the area north of Newfoundland, bringing some polar bears with it.

GREENLAND AND BARENTS SEA

Freeze-up in the Greenland Sea is progressing a bit faster than usual for the last five years (below), but not remarkably so:

Ice cover in the Barents Sea (below) has been slow so far but has been progressing faster over the last few weeks. There is now ice off the east coast of Novaya Zemlya, shorefast ice that should allow any bears summering there to hunt for seals just as Western Hudson Bay bears do during early freeze-up stages. Within the next few weeks, the Arctic pack ice will move south into the Kara Sea, allowing bears to move more freely.Ice off Svalbard has been much below normal (below), as it has been for years now, which is why virtually all Barents Sea pregnant females currently make maternity dens in Franz Josef Land or on the sea ice to the north. These alternative areas for safely giving birth is the primary reason that the much reduced sea ice around Svalbard in recent years has not impacted Barents Sea polar bear health or survival.

KARA SEA

Ice cover in the Kara Sea at 15 December (below) is lower compared to the last five years but it’s unclear how much effect this will have on local polar bears.

Animals that have opted to spend the ice-free season on Novaya Zemlya or on the Russian mainland will have had a long wait for ice, but those that spent the summer on the Severnya Zemlya archipelago to the east had access to sea ice before the end of November. There has been no word from Belushaya Guba on whether the polar bear problems they had because of poorly maintained garbage dumps in December 2018 that went on until February 2019 have recurred this year.

Despite what Andrew Derocher claims (below), there is no evidence that slightly less sea ice in the fall is detrimental to polar bear health or survival in the Kara Sea or elsewhere. It is possible that it might but no one has studied it, so to suggest that low sea ice cover is ‘trouble’ for polar bears at this time of year is very misleading.

CHUKCHI/BERING SEA

Sea ice cover over the Chukchi Sea is a bit lower than it has been over the last few years, about as low as it was in 2017 (below).

Chukchi Sea polar bears at 14 December (below) had abundant sea ice habitat.

In 2016, when Chukchi polar bears were counted for the first time, there was a similar amount of ice at this time of year (below):

REFERENCES

Stirling, I. and Øritsland, N. A. 1995. Relationships between estimates of ringed seal (Phoca hispida) and polar bear (Ursus maritimus) populations in the Canadian Arctic. Canadian Journal of Fisheries and Aquatic Sciences 52: 2594 – 2612. http://www.nrcresearchpress.com/doi/abs/10.1139/f95-849#.VNep0y5v_gU

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commieBob
December 26, 2020 7:21 pm

My eyes glazed over.

Dave Fair
Reply to  commieBob
December 26, 2020 7:40 pm

Polar Bear silence is violence.

commieBob
Reply to  Dave Fair
December 26, 2020 7:54 pm

Yep. They’re white, silent, and violent.

Klem
Reply to  commieBob
December 26, 2020 9:19 pm

You’re not the only one whose eyes glazed over. And because nobody cares about climate change anymore, we now have imposed upon us covid, lockdowns, masks, social distancing, massive election fraud and the Great Reset.

If only we had taken climate alarmists more seriously.

Editor
December 26, 2020 8:40 pm

Andrew Durocher’s tweet claim is misleading, the Arctic warmth he is talking about is WELL BELW FREEZING!

http://ocean.dmi.dk/arctic/plots/meanTarchive/meanT_2020.png

LINK

It is currently around 3 F or -16C which is well above average for the date but still well below freezing.

That is why Anomaly only statements are dishonestly misleading, since that “warmth” is around…. he he…. ha ha…. -16C

They need to post the actual current temperature reading, but that would expose their entire attempt to mislead you, which is why they don’t do it.

Last edited 7 months ago by Sunsettommy
Joel O'Bryan
December 26, 2020 9:03 pm

Ask liar, rent-seeking Derocher one simple question:
“Why are polar bear populations higher today than the 1970’s when it was much colder and more Arctic Sea ice?”

fred250
Reply to  Joel O'Bryan
December 26, 2020 9:31 pm

Simple answer

Polar Bears need a variability in sea ice, because they hunt around the edges.

Having the whole Arctic frozen solid all year is NOT conducive to hunting.

Adam Gallon
Reply to  Joel O'Bryan
December 27, 2020 2:40 am

Because they’re no longer being hunted to extinction levels.

commieBob
Reply to  Joel O'Bryan
December 27, 2020 5:31 am

Fred and Adam are both right.

My favorite question is how the Polar Bears survived the extensive periods during the current interglacial when the arctic was seasonally ice free.

fred250
December 26, 2020 9:12 pm

MASIE shows current extent for day of year, to be above 2010, 2015, 2016, 2017

NSIDC adds 2012, 2013 to that list

In MASIE….

Beaufort, Chukchi, East Siberian, Laptev, Canadian Arch.. are FULL.

Hudson Bay is close to FULL as can be

Kara Sea is currently above that of 2008, 2011, 2012, 2016 and 2018

Greenland sea is above ALL years back to 2006 , except 2007

And of course ALL areas are FAR HIGHER in extent than for most of the last 10,000 years

griff
December 27, 2020 12:13 am

Utterly misleading. for most of the period after the minimum, sea ice was at a record low for date and it only significantly froze around Svalbard, in the Kara and in the Bering in late December.

and if you compared that thickness chart with one from 40 years ago – or stopped to think what that purple means for the next melt season…

David Kamakaris
Reply to  griff
December 27, 2020 4:38 am

Griff, how long is your record?

Graemethecat
Reply to  griff
December 27, 2020 6:44 am

A little advice to you, Griffiepoo: Quit now before you lose all credibility. People are starting to laugh at you.

Graemethecat
Reply to  Graemethecat
December 27, 2020 7:10 am

Oh, and while you’re at it Griffiepoo, perhaps you could explain how Polar Bears survived the seasonally ice-free Holocene era without becoming extinct. Fred250 and I have asked you several times.

Climate believer
Reply to  griff
December 27, 2020 7:10 am

If only you’d stop to think, just once, how much time you waste worrying about something you have no control over. You must feel awful all the time.

How can I sleep?, the purple in December means something….. is it worse than we thought?

Reply to  griff
December 27, 2020 7:44 am

The Hudson Bay ice that does not melt during the summer leads to more ice in the winter….yes, ice leads to ice…..call it accumulation. Does the whole arctic go as Hudson Bay goes?

Editor
Reply to  griff
December 27, 2020 8:06 am

As usual you avoid telling us why low sea ice values are a big deal to the Polar Bears or the world.

All you do is babble about how low it is, many here have seen the same variation of it from you for several years now, meanwhile as usual you miss the main point of the article, which is why you don’t talk about it.

Don’t you have new material to offer aside from the same old “it is low” whine?

Pat from kerbob
Reply to  Sunsettommy
December 27, 2020 9:11 am

Let me answer for Grifter

“No”

fred250
Reply to  griff
December 27, 2020 10:02 am

“sea ice was at a record low for date”

WRONG!!!!

Arctic sea ice this year has been FAR ABOVE most of the last 10,000 years

Stop being an pathetic CLIMATE CHANGE DENIER , griff,

Shows you to be an IGNORANT, brain-washed, anti-science dolt.

fred250
Reply to  griff
December 27, 2020 10:19 am

“froze around Svalbard”

WRONG AS ALWAYS

Russian Ice charts… http://www.aari.ru/odata/_d0015.php?lang=1

Show MORE ICE around Svalbard for this date than in 2018, 2017, 2016, 2015, 2012

And a similar amount to now in 2011, 2009, 2007, 2006, 2004, 2005

Why are you ALWAYS getting caught either LYING or showing your ABJECT IGNORANCE.

——–

40 years , since the anomalous EXTREME HIGH of the 1970s ???

What a pitifully short period, from a childish cherry-picked start date, hey griff. !

You do know that current levels of Arctic Sea ice are FAR HIGHER than for most of the last 10,000 years, don’t you ? !!!

How did the polar bears exist. 😉

fred250
Reply to  griff
December 27, 2020 10:31 am

In MASIE, Kara Sea extent is now ABOVE that of day 361 of 2007, 2008, 2011, 2012, 2015, 2016, 2018

and above the 14 year average.

Bering Strait is extent is above 2014, 2016, 2017, 2019

There is NOTHING untoward happening to Arctic Sea ice …

… except that is still SO MUCH MORE than for most of the last 10,000 years.

Reply to  griff
December 27, 2020 1:14 pm

Griff, you are a good example to explain the Pavlovian response 😀

commieBob
Reply to  griff
December 27, 2020 4:54 pm

… think what that purple means for the next melt season …

… not as much as you seem to think. The final thickness depends on the temperature between now and the melt season. As for the current extent, it’s right where it’s been in recent years.

Mick Walker
December 27, 2020 10:21 am

Well, I like Griff! 🙂
We should encourage her, to keep everyone on their toes.

Okay, she’s not very good at it, but she does her best, and she’s persistent.
And let’s be fair, she doesn’t have much to work with, in a well-informed forum like this.

I hope WUWT never adopts the Ars Technica comment system, where dissenters’ comments are removed when they get enough down-votes. Dissenticide. It’s not healthy.

It’s no fun arguing with people who agree with you!
And the Griffalo can help to keep silly mistakes in check. Theoretically.

Keep it up, Griffy!

December 27, 2020 11:45 am

Just like the recent shard that broke off from Antarctica is ginormous, but well within acceptable ranges for that biosphere. Yay science 💫🕳🤟

tommyboy
December 28, 2020 9:06 am

I’m surprised no one knows how much hunting the bears do during the polar night. I’m not volunteering to follow bears around in the darkness but I would think using the tracking information of tagged bears would be enough to discern what they’re doing.

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