Western & Southern Hudson Bay polar bears experience earliest freeze-up in decades

Reposted from Polar Bear Science

Posted on November 3, 2020

This is shaping up to be one of the shortest ice-free seasons in at least 20 years for both Western and Southern Hudson Bay polar bears.

Hudson Bay sea ice at 2 November 2020. NSIDC Masie chart.

Last week, sea ice started forming along the shore of Hudson Bay, from the north end all the way south into James Bay. So far, the shorefast ice that’s forming is only a narrow strip along the coast but is thickening and becoming broader each day, which means that unless something changes dramatically, the bears should all be on the ice at the end of the week, an exodus from shore that hasn’t happened this early in WH since 1993 (the earliest since 1979).

The last WH tagged polar bear didn’t leave the ice this year until 21 August, which means if it’s on the ice by the end of this week it will have spent only 11 weeks onshore – less than 3 months. Even the first bears that came ashore in mid-July will have only spent about 16 weeks on land – at least a month less than they did a decade ago (Stirling and Derocher 2012). Four months spent ashore was the historical average for Western Hudson Bay bears in the 1970s and 1980s (Stirling et al. 1977, 1999). This year, most polar bears will have spent only about 13-14 weeks on land because they did not come ashore until early August.

Freeze-up dates since 1979

I am using a definition of “freeze-up” that describes the behaviour of polar bears to newly formed ice, not the date when fall ice coverage on the bay reaches 50% (e.g. Lunn et al. 2016). According to a recalculation of WH data that goes up to 2015 and back to 1979 (Castro de la Guardia 2017, see graph below), in the 1980s bears left for the ice at freeze-up (10% sea ice coverage) about 16 November ± 5 days. The earliest the bears left the ice was in 1991 and 1993, on 6 November (Julian day 310).

The first week of November is very early for bears leaving for the ice.

Figure 3 from Castro de la Guardia (2017) showing freeze-up and breakup dates and ice-free days 1979-2015 for Western Hudson Bay, showing that the earliest freeze-up dates since 1979 (top panel) came on 6 November, Day 310 (in 1991 and 1993).

Therefore, freeze-up dates of 10-12 November or so (Day 314-316) for 2017, 2018, and 2019 are some of the earliest freeze-up dates recorded since 1979 (the earliest being 6 November, Day 310, in 1991 and 1993), even earlier than the average for the 1980s. And 2020 is earlier still.

Virtually all Western Hudson Bay bears leave the shore within about 2 days of sea ice concentration reaching 10% (Castro de la Guardia 2017), although Southern Hudson Bay bears leave when it reaches about 5%: in other words, the bears go as soon as they possibly can. As I discussed in 2016 regarding newly-published studies (Obbard et al. 2015, 2016) on the status of Southern Hudson Bay (SH) bears:

“…SH polar bears left the ice (or returned to it) when the average ice cover near the coast was about 5%. This finding is yet more evidence that the meteorological definition of “breakup” (date of 50% ice cover) used by many researchers (see discussion here) is not appropriate for describing the seasonal movements of polar bears on and off shore.”

The earliest freeze-up date for Southern Hudson Bay appears to be about 11 November (Julian day 315), based on data in a paper by Obbard and colleagues in 2016. So freeze-up is early for these bears as well.

Despite this being the best of six very good years for the polar bears of Western Hudson Bay, activist polar bear scientists continue to sell the public their false message of doom based on data from years ago. As I’ve mentioned previously, polar bear data from Western Hudson Bay prior to these good years (i.e. up to 2009 only) was used for the latest model (Molnar et al. 2020) predicting future conditions for polar bears elsewhere in the Arctic. These good years for sea ice and bears have simply been ignored in long-term projections.

Hiding the good news

Polar bear biologist Derocher recently said the timing of sea ice formation this year is ‘normal’:

Yesterday’s satellite image has little ice forming near Rankin Inlet. It’s -11 C (12 F) so ice should form soon. Timing is about normal. NW Hudson Bay is where the 1st ice forms. Ice moves south on winds & piles up along shore east of Churchill where many polar bears are waiting. https://t.co/EQH390707H pic.twitter.com/vbWnbT0p0c— Andrew Derocher (@AEDerocher) October 28, 2020

However, charts from the Canadian Ice Service indicate otherwise.

In their ‘Departure from normal’ chart for the week of 2 November 2020, sea ice formation along the entire western coast of Hudson Bay is ‘greater than normal’ and ‘much greater than normal’ (blue and dark blue), below. Only the very northern portions are slightly less than normal (pink):

Daily charts for Hudson Bay north and south are below for 3 November: dark purple areas (‘grey ice’) were light purple the day before (‘new’ ice):

WH polar bears and sea ice photos

Probably the same triplet litter as spotted in September was seen again on 31 October getting ready to leave for the ice. How many more of these triplet litters are out there? They are rarely seen now although they used to be common. Last one before this was photographed in 2017 north of Churchill. But while these large litters may now be more rare than they used to be, they have not disappeared. In other regions, triplet litters are an indicator of a healthy population.

Mother with triplet cubs, 31 October 2020. Dave Allcorn photo.

All of the bears spotted hanging around waiting for the sea ice have been fat and healthy (e.g. below).

Three fat bears, 31 October 2020. Wakusp National Park.

On Saturday, a polar bear mother with two cubs went out on the ice and caught a seal (below).

Polar bears on a seal kill, 31 October 2020. Wakusp National Park.

Mother with two cubs, sea ice in the background. Wakusp National Park, 3 November 2020.


Castro de la Guardia, L., Myers, P.G., Derocher, A.E., Lunn, N.J., Terwisscha van Scheltinga, A.D. 2017. Sea ice cycle in western Hudson Bay, Canada, from a polar bear perspective. Marine Ecology Progress Series 564: 225–233. http://www.int-res.com/abstracts/meps/v564/p225-233/

Lunn, N.J., Servanty, S., Regehr, E.V., Converse, S.J., Richardson, E. and Stirling, I. 2016. Demography of an apex predator at the edge of its range – impacts of changing sea ice on polar bears in Hudson Bay. Ecological Applications 26(5): 1302-1320. DOI: 10.1890/15-1256

Molnár, P.K., Bitz, C.M., Holland, M.M., Kay, J.E., Penk, S.R. and Amstrup, S.C. 2020. Fasting season length sets temporal limits for global polar bear persistence. Nature Climate Change. https://doi.org/10.1038/s41558-020-0818-9

Obbard, M.E., Stapleton, S., Middel, K.R., Thibault, I., Brodeur, V. and Jutras, C. 2015. Estimating the abundance of the Southern Hudson Bay polar bear subpopulation with aerial surveys. Polar Biology 38:1713-1725.

Obbard, M.E., Cattet, M.R.I., Howe, E.J., Middel, K.R., Newton, E.J., Kolenosky, G.B., Abraham, K.F. and Greenwood, C.J. 2016. Trends in body condition in polar bears (Ursus maritimus) from the Southern Hudson Bay subpopulation in relation to changes in sea ice. Arctic Science 2: 15-32. DOI: 10.1139/AS-2015-0027

Stirling, I. and Derocher, A.E. 2012. Effects of climate warming on polar bears: a review of the evidence. Global Change Biology 18:2694-2706. doi:10.1111/j.1365-2486.2012.02753.x

Stirling I, Jonkel C, Smith P, Robertson R, Cross D. 1977. The ecology of the polar bear (Ursus maritimus) along the western coast of Hudson Bay. Canadian Wildlife Service Occasional Paper No. 33. pdf here.

Stirling, I., Lunn, N.J. and Iacozza, J. 1999. Long-term trends in the population ecology of polar bears in Western Hudson Bay in relation to climate change. Arctic 52:294-306. http://arctic.synergiesprairies.ca/arctic/index.php/arctic/article/view/935/960

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November 5, 2020 10:18 am

I know, griff knows better 😀 😀

Reply to  Krishna Gans
November 5, 2020 10:49 am

Griffo’s knowledge is never better, just different.

Reply to  Vuk
November 5, 2020 12:33 pm

And RARELY related to REALITY in any way whatsoever.

Reply to  fred250
November 6, 2020 12:49 am


Reply to  Krishna Gans
November 5, 2020 5:23 pm

There is no Griff !
He is actually the alter-ego of our beloved Moderator, Charles Rotten, formerly performing as Johnny Rotten, with the Sex Pistols, who came up with a new way to generate more page views here. Mr. Rotten invented the Grifter, based on the old Johnny Carson comedy character, Floyd. R. Turbo, with a leftist spin. Mr. Rotten, when things are slow here, is sitting on his regular “office” bar stool, coming up with a new Grifter comment to stir up the climate skeptics here. And stir up the skeptics he does — like a prison guard walking past prison cells at night banging his night stick on the steel bars. … Almost as much reaction as throwing a bunch of bananas in the monkey cage at the zoo.
Moderator Bait

Reply to  Krishna Gans
November 5, 2020 10:32 pm

Griff is in lockdown he cant get to work as “paid troll” is not an essential service.

Ron Long
November 5, 2020 10:19 am

They’re polar bears, not teddy bears, they’ll deal with it. New normal?

November 5, 2020 11:10 am

If it’s not in WWF marketing materials it can’t be true. The teen T-shirts and address labels say so.

November 5, 2020 11:47 am

Wapusk, not Wakusp. Fat little bears.

Crispin in Waterloo but really in Carrying Place
Reply to  TD
November 5, 2020 12:09 pm

It looked like Wake us up, not WhatsApp or Whap us, ‘k?

Crispin in Waterloo but really in Carrying Place
November 5, 2020 12:07 pm

For powerful, relentless, vicious killers, they look cute. The sooner they get on the ice and out of populated neighbourhoods, the better.

It looks like a bumper year once again the the PB population. If they get out of hand, we can increase the hunting harvest. It is a very important part of annual income for rural communities.

Reply to  Crispin in Waterloo but really in Carrying Place
November 5, 2020 5:27 pm

Crisptoast in Waterloo
I have organized a new organization: LEAVE THE POLAR BEARS ALONE
Our motto: “We don’t need no stinkin’ tags”
Membership so far: 23 polar bears, and one peculiar man in a polar bear suit.

November 5, 2020 12:15 pm

We shouldn’t be fat-shaming those poor polar bears. 😉

Reply to  PaulH
November 5, 2020 3:16 pm

They are not “fat” they are “well-proportioned” PBs

Where is griff ????

Why isn’t he hear to CHEER ON the early onset of sea ice in the Hudson. 😉

Reply to  fred250
November 5, 2020 3:55 pm

He’s still hung over from celebrating the current Laptev Sea ice data.

Reply to  philincalifornia
November 5, 2020 6:10 pm

Not on home computer so can’t check…

iirc Laptev has taken off like a rocket.

Did a calc yesterday, as far as I can tell, the last 4 days had the fastest 4 day Arctic sea ice growth since 1988.

(data before that is two day steps, and I couldn’t be bothered checking them, because I already know the month October/November gains in the last 30 years have been higher than most of the 1980s)

November 5, 2020 12:41 pm

Those poley bars APPEAR to be healthy, but inside they’re just worried SICK about the “climate crisis”.

Reply to  Mr.
November 5, 2020 6:11 pm

nahh… I don’t think that read fantasy non-science.. !

Reply to  Mr.
November 6, 2020 5:18 am

Stress causes comfort eating.

November 5, 2020 1:02 pm

A polar vortex in the lower stratosphere over Hudson Bay.

Reply to  ren
November 5, 2020 3:12 pm


Please post time-stamped links for Nullschool.
Otherwise your point will be soon be lost as the date changes.
Thank you

Reply to  ren
November 6, 2020 7:16 am


No, the vortex is located/centered about 1,500 miles to the north over the north extreme of the Canadian Archipelago, Borden Island to be exact…and it’s very shallow too – meh..

Attention to detail is important.

Reply to  JKrob
November 6, 2020 2:10 pm

No, this is one of the two centers of the polar vortex, and its edge is over Hudson Bay.
comment image

Al Miller
November 5, 2020 1:24 pm

What?, I must have missed that in the “news”. It sounds like a big story that should make everyone feel better. I’m sure they’ll be all over it tomorrow…

Gary Pearse
November 5, 2020 3:12 pm

Isn’t it grossly dishonest in the extreme for the PBG to withhold results of a survey done in 2012 on the status of bears that showed very positive numbers and health data? It seems they actually believed their theory about reduced ice wiping out bears and thought the situation would surely turn back down in a year or two… or 3-4…

Each passing year now would be a greater embarrassment to release the findings and reveal behavior unworthy of scientists. My call is that now they will never release this survey. Some new group of zoologists will see stories of healthy bears, read about bears becoming a greater nuisance near towns, etc. and takeover as the new specialists cutting these dishonest people adrift.

It will be a loathsome world if Trump has this election stolen from him. The immoral goings on of the left in the US election is unsurprisingly exactly the same thing that’s going on in grotty, suborned climate, designer-brained education K to-left-half of-the-bell-curve PhDs by the boatload, and across the human landscape. Otherwise things are looking up.

David Kamakaris
Reply to  Gary Pearse
November 5, 2020 3:46 pm

“Otherwise things are looking up.”
For sure!
Except for that, how was the play, Mrs. Lincoln?

Reply to  Gary Pearse
November 5, 2020 5:24 pm

The Presidency is damaged goods. Whoever is inaugurated in January will be considered illegitimate and a lame-duck by half the country. That, plus a divided Congress, means absolutely no legislation of consequence will be passed for the next four years.

At this point, I hope Trump loses, forms a shadow government, campaigns in every state for the next four years, and wins overwhelmingly in 2024, with a Republican House and Senate, and a strict Constitutionalist Supreme Court.

Reply to  jtom
November 5, 2020 8:04 pm

” plus a divided Congress, means absolutely no legislation of consequence will be passed for the next four years”

What we do without them ??

Reply to  philincalifornia
November 5, 2020 8:05 pm

would we do even

Reply to  Gary Pearse
November 7, 2020 8:41 am

EXACTLY true. I THINK “The Cassandra Frauds” of ‘Noble Causes’ which in turn have been institutionalised against proven success (thereby destroying its raison d’être), and from there, spread out from there to destroy the functional integrity of more and more fields.

It all began with ecologism and environmentalism. With climategate on 2009, we saw another field destroy itself and turn into politicised mush and nonsense.

How many field of inquiry have fallen since then? Too many.

You might blame the benefits of the grift, but if honesty and integrity were maintained, where would the schemers and grifters be? Unemployed.

Instead it has turned into a metastasising creed, a bureaucratic machine commanding ever greater funded feedings, afflicting mor and more of the body politic, pushing out reason and restraint.

It has become the never ending epidemic of our time. Built on falsehoods and deception.

November 5, 2020 4:11 pm

Here at the Walrus Liberation Front we’re planning new measures to get our message across so consider yourselves warned bipeds. We have Navy SEALS!

November 5, 2020 4:56 pm

It must be getting cold up there. The Sandhill cranes have been migrating over mid west Georgia the last couple of days.

Dennis G Sandberg
November 5, 2020 5:35 pm

Gary, If the data doesn’t fit the agenda, ignore it. If it persists manipulate it. Continues as a problem? Lose it. “designer-brained education K to-left-half of-the-bell-curve PhDs by the boatload” are smart, trained and happy to help, because after all they’re saving the planet.

November 6, 2020 12:03 am

And in the Kara Sea? Off Svalbard? The Bering Straits? There ain’t no ice there… and I think a tiny strip along the edge of the Bay is really not a full scale freeze up.

concentrating on marginal bits of ice without looking at the larger picture is frankly dishonest

Reply to  griff
November 6, 2020 12:45 am


Current levels of Arctic sea ice are far above the Holocene normal.

Even with the current HIGH LEVELS OF ARCTIC SEA ICE, the slight recovery to more NORMAL levels has bee of huge benefit to Arctic sea life

Not only is the land surface GREENING, but the seas are also springing BACK to life after being TOO COLD and frozen over for much of the last 500 or so years (coldest period of the Holocene)

The drop in sea ice slightly toward the pre-LIA levels has opened up the food supply for the nearly extinct Bowhead Whale, and they are returning to the waters around Svalbard.


The Blue Mussel is also making a return, having been absent for a few thousand years, apart from a brief stint during the MWP.


Many other species of whale are also returning now that the sea ice extent has dropped from the extreme highs of the LIA. Whales cannot swim on ice. !


Great thing is, that because of fossil fuels and plastics, they will no longer be hunted for whale blubber for lamps and for whale bone.

Hopefully the Arctic doesn’t re-freeze too much in the next AMO cycle, and these glorious creatures get a chance to survive and multiply.

From the second link..
“Shallow marine molluscs that are today extinct close to Svalbard, because of the cold climate, are found in deposits there dating to the early Holocene. The most warmth-demanding species found, Zirfaea crispata, currently has a northern limit 1000 km farther south, indicating that August temperatures on Svalbard were 6°C warmer at around 10.2–9.2 cal. ka BP, when this species lived there. The blue mussel, Mytilus edulis, returned to Svalbard in 2004 following recent warming, and after almost 4000 years of absence, excluding a short re-appearance during the Medieval Warm Period 900 years ago.

Arctic is so much COOLER than it was for most of the Holocene, which explains why there is still so much sea ice up there.

Come on griff, stop being a COWARD and answer the question

Do you have any evidence at all that the highly beneficial drop in Arctic sea ice from the extreme highs of the LIA and late 1970s has any human causation at all?

Reply to  griff
November 6, 2020 1:38 am

Beaufort Sea: FULL

Canadian Archipelago: FULL !

East Siberian Sea: about 2/3 full and climbing rapidly

Laptev Sea: about 2/3 full and climbing rapidly

Chukchi: About half full

Kara Sea: above 2012 and 2016

WOW, there is ONE HECK OF A LOT of sea ice up there, Isn’t there , griff

FAR MORE than for NEARLY ALL of the last 10,000 years

Reply to  griff
November 6, 2020 2:36 am

Griff u aren’t very bright and I have pointed this out to u before but here it is again …. this time of year there is never anything but a “strip of ice along the shore” …. look at this from the Canadian Ice Services:
Here is the link to the full Canadian site https://www.canada.ca/en/environment-climate-change/services/ice-forecasts-observations/latest-conditions.html
Also it is a full scale freeze up and it happens very quickly over the next several weeks … temps are all in the -10 to -20 C range. You have likely never experienced -20 temps living where u do and have no idea how bloody cold that is!!

Reply to  stewartpid
November 6, 2020 6:57 am

Hmmm … my first link won’t work. Perhaps the jpeg will link https://ice-glaces.ec.gc.ca/prods/CVCSWCTHB/20201102180000_CVCSWCTHB_0011305117.pdf

If no luck go to my second link which works and open Hudson Bay and then scroll down to #30 the weekly ice coverage graph.

Climate believer
Reply to  stewartpid
November 6, 2020 10:32 am

Facts are an anathema to alarmists.


Tom Abbott
Reply to  griff
November 6, 2020 4:58 am

“concentrating on marginal bits of ice without looking at the larger picture is frankly dishonest”

There you go again, Griff, trying to assasinate the character of Dr. Susan Crockford.

This is a habit with you. Anyone who makes an argument that blows up the alarmist theory is attacked by you on a personal basis. I suppose this is your way of psychologically dismissing any views that don’t agree with yours.

Character assasination is your fall-back position, Griff. It’s part of your tool chest. Not that you are the only one that does this, it is pretty much standard procedure for those on the Left.

You should apologize to Susan Crockford for the smears you made against her in the past and for this smear of her character.

In the future, perhaps you could just stick to the facts and leave your uninformed personal opinions about other people out of it.

Climate believer
Reply to  griff
November 6, 2020 10:07 am

…..”frankly dishonest”…..

What a hypocrite, and your comment is totally disingenuous.

mr bliss
November 6, 2020 8:47 am

‘Fact-Checkers’ on facebook and twitter have declared that pics of fat, healthy polar bears are clearly fake and will be restricted

November 6, 2020 11:54 am

“pics of fat, healthy polar bears are clearly fake and will be restricted”

If true then here is something else that needs to be restricted:
Polar Bear Cam Wapusk National Park, Manitoba

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