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Polar bear habitat: Spring 2014 in Eastern Canada was much better than 1969

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It was a good year for polar bear habitat in the southern portions of Eastern Canada this spring – surprisingly, much better than it was in 1968 through 1970. And since spring conditions are what really matter to polar bears, this is good news indeed.

Environment Canada’s Canadian Ice Service recently published a nice little summary that has some rather eye-opening graphs. These describe the conditions for polar bears in the southern Davis Strait subpopulation – the one whose population size increased so dramatically between 1974 and 2007 despite lower-than-average ice extent in some years, even while their body condition declined (see here and here).

Environment Canada - Ice maps regions at July 26 2014

[Fitting post for the second anniversary of this blog, I think – more below1]

Note that I’ve added a “Blog Archive” page that lists all of my posts, easier to browse now that there are more than 200 of them.

Here’s what the Canadian Ice Service says about this winter-spring season (ending 18 June), with a few of the graphs and ice charts they provided below:

“Air temperatures on the East Coast over the 2013-2014 winter season were overall colder than normal, with December and March being much colder than the 1980-81 to 2009-2010 climate normal. This contributed to an above normal amount of ice for each of the Gulf, Newfoundland and Southern Labrador Coast regions. There was more than twice as much ice during the 2013-2014 season than the median of the previous 10 years.

The severity of the 2013-2014 ice season was felt particularly around Newfoundland as the pack ice reached most of the west coast of Newfoundland in the first week of February and started clearing only in mid-April. On the east side of the island, the ice coverage reached its maximum extent around mid-March, when the pack ice followed the Labrador Current and drifted all the way down to about 45N, before starting to retreat later in the month. Some ice lingered in Notre Dame Bay and White Bay until the last week of June before melting. These areas usually clear before the end of May. The last season that had more ice in East Newfoundland Waters was 1993-1994.

In the Gulf of St Lawrence, the maximum ice coverage was also reached around mid-March. Clearing occurred in the estuary in early April, which is near normal. The pack ice disappeared from the southern portions of the Gulf at the end of April, about two weeks later than normal. Some ice lingered in the northeast sections of the Gulf until the third week of June before melting, more than three weeks later than normal. The last season that had more ice in the Gulf was 2002-2003.” [my bold]

Weekly Ice Coverage for the East Coast season, CIS

Weekly Ice Coverage for the Canadian East Coast season, 2014 (to 18 June). CIS.

Maximum ice coverage for the East Coast, CIS

Maximum ice coverage for the Canadian East Coast, 2014 (10 March). CIS.

See the full report here and a similar one, without graphs and charts, for all regions of the Canadian Arctic for the spring of 2014 including Hudson Bay, here.

But have a look at the graphs below, that show how little ice there was in this region in the late 1960s (the winters of 1968/69 and 1969/70) — the maximum total for the winter of 1968/69 was almost as low as 2010 (the lowest overall) and the highest extent was not in the 1970s but in 1990!

[Keep in mind that this region is the most southern region supporting polar bear populations in the world, to at least 470N in the south (see Fig.1 here), so what happens in southern Davis Strait should reflect some of the most extreme fluctuations in polar bear habitat globally]

Makes me wonder – if we had data going back a few more decades, recent lows wouldn’t look so unusual. It might look more like a cyclic pattern of high-low ice over decadal time scales than a slow steady decline since 1979 (when comprehensive satellite-gathered sea ice data began).

Maximum ice coverage for the East Coast 1969-2014, CIS.

Maximum ice coverage for the East Coast 1969-2014 (to 18 June), CIS.

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Footnote about this blog’s 2nd anniversary:

Accumulated views over two years — 227,210 (July 26, 2012 to July 25, 2014 at midnight).

Stats at July 26 2014_by month_PBS

Views by country for this period (July 26, 2012-July 26, 2014 a.m.) below:

PBS_views by country map_July 26 2012 to July 26 2014 at 0737


Polar bears out on the sea ice eat few seals in summer and early fall

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We hear endlessly about the polar bears ‘forced’ to go without food for months because of receding summer sea ice — what about all the bears that stay out on the ice over the summer? Presumably, those bears keep hunting for seals – but how many do they actually catch?

Polar Bear Breaks Ice

[Update 9 February 2015: Just to be clear, this post is based on the facts available in the peer reviewed literature — if you think I have missed something, let me know via the “Contact us” page above]

As it turns out, not very many – and for some unlucky bears in late summer, probably none. While they probably eat a bit better in late fall, if they’re lucky and persistent, by the time winter comes, biologists assume most bears again eat very little. This explains why all polar bears are at their lowest weight in late winter (March), just before Arctic seal pups are born.

[Winter – January to March; Spring – April to June; Summer – July to September; Fall – October to December (e.g. Pilfold et al. 2015, in press)]

To put it another way, the reason that polar bears in some areas easily survive an onshore fast of 4 months or more over the late summer/early fall is that they would get very little to eat (if anything) even if they stayed out on the ice. It’s the fat put on in spring/early summer (from gorging on baby seals) that carries them over the summer, no matter where they spend it.

So why do some polar bear biologists and others (e.g. Stirling and Derocher 2012) keep insisting that if late summer sea ice retreats even more in the future than it has in recent years, polar bear survival will be seriously compromised because they won’t be able to eat? For example, Morrison and Kay (2014) made the following astonishing claim last September on the Polar Bears International website, apparently approved by PBI’s ‘chief scientist’ Dr. Steve Amstrup:

Summer is the limiting season because polar bears depend on sea ice as a platform to hunt seals. With summer and early fall sea ice losses, polar bears have less time on the ice, eat less, and become skinnier.”

Really? Take a look at the facts.

The importance of spring seals
Hammill and Smith (1991:132), studying polar bear predation on ringed seals in the Lancaster Sound region of the central Canadian Arctic (Barrow Strait, see Fig. 1 below), had this to say:

Prior to late April, we found little evidence of predation in Barrow Strait. In late spring, polar bears enter a period of intense feeding (Stirling and McEwan 1975, Ramsay and Stirling 1988), which begins with the onset of the ringed seal pupping season. …Feeding on young seals continues throughout the spring and early summer as bears replenish depleted fat reserves. After ice breakup, bears move ashore and begin another period of little feeding (Stirling and McEwan 1975, Ramsay and Stirling 1988).” [my bold]

OK, but don’t polar bears keep hunting during the late summer and early fall in areas where sea ice is available, like the Beaufort, Chukchi and Barents Seas? Indeed they do but it appears that polar bears spend less time hunting, and are often far less successful, than they are in spring. 1

Evidence for rates of successful summer hunting
Ian Stirling (1974) reported his summer observations of polar bears from a high observation tower available on southern Devon Island (near Barrow Strait) in the central Canadian Arctic between 24 July and 8 August (Fig. 1). He noted that only five seals were caught during 602.7 hours of bear observations – and that was in 1973, before summer sea ice declines were an issue.

Stirling attributed this “low success rate” to the fact that there are a large number of natural holes in the ice during the summer, which offers seals more escape routes. Stirling noted that the bears he observed spent about 30% of their time sleeping, 12% just lying around, 25% walking and 4% swimming (usually without any apparent purpose) – compared to spending just 2% of their time feeding.

Ironically, that’s slightly less time feeding than Southern Hudson Bay polar bears spent during their time onshore during the summer! A study of James Bay bears in 1969 and 1970 found they spent 3.2% of their time feeding on geese and berries (Knudsen 1978).

Figure 1. Devon Island in the central Canadian Arctic, adjacent to Barrow Strait, where Ian Stirling observed polar bears from a tower during the summer of 1973 (24 July to 8 August). Wikipedia map.

Figure 1. Devon Island in the central Canadian Arctic, adjacent to Barrow Strait, where Ian Stirling observed polar bears from a tower during the summer of 1973 (24 July to 8 August). It is within the Lancaster Sound polar bear subpopulation. Wikipedia map.

Stirling and a colleague later added more feeding frequency data to Stirling’s 1973 observations, gathered from the same area in 1974 and 1978. Stirling and Øritsland (1995) used that data to create a generalized, month-by-month estimate of the number of ringed seals killed per day of polar bear hunting effort (Fig. 2, below). In this analysis, bears out on the pack ice were assumed to kill only one seal per month over the late fall/winter months of December through February and two per month in the late fall (October/November). They explained:

A monthly kill of zero was set for August and September because open water prevails in most areas, although we recognize that bears on drifting ice still kill some seals. There are no data on the rates at which polar bears kill seals in the late fall after freeze-up when young annual ice is widespread and seals become accessible again. However, from observations in the Beaufort Sea and on the western coast of Hudson Bay, where polar bears summer on the multiyear pack ice and land, respectively, the bears move onto the young annual ice to hunt as soon as possible after freeze-up and the remains of seals killed there by bears have been observed (Stirling 1974b; Latour 1981; Derocher and Stirling 1990; 1. Stirling, unpublished data). Although this suggests that fall feeding during freeze-up could be important, in the absence of data we conservatively set the kill rate at 15 days of hunting per seal killed per bear. There are no data for the winter months, so an arbitrary rate of one seal kill per bear per month was assigned.” [my bold]

Figure 2. This is Table 2 from Stirling and Øritsland (1995), showing their estimation of the number of ringed seals killed by polar bears each month in the central Canadian Arctic in the 1970s. Note that numbers of seal kills for winter months are assumptions (no data available) and that bears are assumed to spend the summer months (August, September) onshore fasting (although some bears spent that time on the pack ice, as did the bears in Stirling’s 1973 study).

Figure 2. This is Table 2 from Stirling and Øritsland (1995), showing their estimation of the number of ringed seals killed by polar bears each month in the central Canadian Arctic in the 1970s. Numbers of seal kills for winter months are assumptions (no data available) and bears are assumed to spend the late summer months (August, September) onshore fasting, even though some bears spent that time on the pack ice (as did the bears in Stirling’s 1973 study). Click to enlarge.

Another study provided no information on rates of polar bear feeding episodes but did report month-by-month evidence of seal kills found on the ice between 1984 and 2001 in the Svalbard/Barents Sea area (March to October). Derocher and colleagues (2002:449) recorded only 24 seal kills (various species, including ringed, bearded and harp seals) in August (the only summer month reported), less than half of the 58 kills recorded in April (highest kills for a spring month); only one kill was recorded in October. So, while it is clear that some bears were eating over the summer in the Barents Sea, we don’t have any idea how many bears were responsible for the seal kills found on the ice.

Finally, confirmation that this pattern of limited hunting success from summer through winter is considered typical of all polar bear populations comes from a just-released paper on polar bear feeding by Nicholas Pilfold and colleagues Andrew Derocher, Ian Stirling and Evan Richardson (Pilfold et al. 2015 in press).

These authors suggest that the feeding budget presented by Stirling and Øritsland in 1995 (Fig. 2) is still true now, even for the eastern Beaufort Sea bears they studied:

Polar bears are hyperphagic in spring and may acquire as much as two-thirds of the energy requirement for the year, providing fat reserves for survival through periods of low prey access during the summer melt season (Stirling and Øritsland 1995).” [my bold]

Two-thirds of a year’s food supply consumed over three months (April – June) is the same as eight twelfths (2/3 = 8/12). That means 4 months worth of food is generally consumed over the remaining 9 months of the year. That’s not very much per month, spread over summer, fall and winter — especially since most of it is consumed during late fall2.

Conclusions
Some polar bear biologists, and others, continue to claim that future declines in summer sea ice coverage are a serious threat to polar bear survival because it reduces their access to their prey (e.g., Stirling and Derocher 2012). However, observations made well before summer ice declines became dramatic3, polar bears were rarely successful at seal hunting in summer because it was so much easier for seals to escape.

This means that even under the best of conditions, bears spending summers on the sea ice do not eat very often and some probably don’t eat at all. Even for bears that achieve a limited degree of hunting success, this reduced summer feeding probably approaches a “semi-fasting” situation, while unsuccessful hunters may fast as completely as bears spending summers onshore.

This underscores the importance of the spring and early summer feeding period for all bears and shows how misleading it is to focus on recent declines — and potential future declines — of sea ice coverage at the end of summer (September).


Footnote 1: Keep in mind that young bears that haven’t mastered the tricks of successful hunting will always be at risk of starvation, as they have always been – if they can’t put on enough weight in spring, they won’t last through the following summer, fall and winter of low feeding opportunities. Steven Amstrup (2003) pointed out that starvation is probably the leading cause of death for young and old bears alike.

Starvation of independent young as well as very old animals must account for much of the natural mortality among polar bears… Also, age structure data show that subadults aged 2-5years survive at lower rates than adults (Amstrup 1995), probably because they are still learning hunting and survival skills.”

I once observed a 3-year-old subadult that weighed only 70 kg in November. This was near the end of the autumn period in which Beaufort Sea bears reach their peak weights (Durner and Amstrup 1996), and his cohorts at that time weighed in excess of 200 kg. This young animal apparently had not learned the skills needed to survive and was starving to death. [my bold]

Footnote 2: This statement by Pilfold and colleagues suggests that the conclusion drawn by Durner and Amstrup in (1996), regarding weights of Southern Beaufort Sea bears in Alaska (1983-1994), was misleading and/or mistaken. Durner and Amstrup stated that “bears of similar length were consistently heavier in autumn than in spring” (although they didn’t actually say by how much – it could have been only a kg or two). Their result was derived from a model designed to estimate body weights from girth measurements and body length, not a conclusion based on comparing weights over time of individual bears. Durner and Amstrup interpreted this result to mean that individual Beaufort Sea bears were lighter in spring than they were in autumn (when captured in October or November) – in contrast to all other populations studied (see also Amstrup 2003, quoted in footnote 1). While that could be interpreted to mean that Beaufort Sea bears continue to feed reasonably often over the summer, it is perhaps more plausible to suggest that they are more successful than average at hunting in the early fall — and thus regain lost summer weight more quickly.

Footnote 3: Sea ice changes since 1979 shown below, from NOAA’s “2014 Arctic Report Card,” in the sea ice chapter. Summer sea ice (September minimum, red) has declined dramatically since 1979 but spring ice (March maximum, black) has declined only slightly.

Sea Ice Figure 4.2 from NOAA's "Arctic Report Card 2014"

Sea Ice Figure 4.2 from NOAA’s “Arctic Report Card 2014″

References
Amstrup, S.C. 2003. Polar bear (Ursus maritimus). In Wild Mammals of North America, G.A. Feldhamer, B.C. Thompson and J.A. Chapman (eds), pg. 587-610. Johns Hopkins University Press, Baltimore.

Derocher, A.E., Wiig, Ø., and Andersen, M. 2002. Diet composition of polar bears in Svalbard and the western Barents Sea. Polar Biology 25 (6): 448-452. http://link.springer.com/article/10.1007/s00300-002-0364-0

Durner, G.M. and Amstrup, S.C. 1996. Mass and body-dimension relationships of polar bears in northern Alaska. Wildlife Society Bulletin 24(3):480-484.

Hammill, M.O. and Smith T.G. 1991.
The role of predation in the ecology of the ringed seal in Barrow Strait, Northwest Territories, Canada. Marine Mammal Science 7:123–135.

Knudsen, B. 1978. Time budgets of polar bears (Ursus maritimus) on North Twin Island, James Bay, during summer. Canadian Journal of Zoology 56(7): 1627- 1628. http://www.nrcresearchpress.com/doi/abs/10.1139/z78-224#.VNZWHy5v_gU
Abstract

During the summers of 1969 and 1970 polar bears (Ursus maritimus) were observed on North Twin Island (53°20′ N; 80°00′ W), James Bay. Almost all of their time (86.8%) was spent resting. They spent only 3.2% of their time feeding, primarily on geese (Branta canadensis) and crowberries (Empetrum nigrum). There was no difference between the time budgets of lone bears and females accompanied by cubs.

Morrison, A. and Kay, J. 2014. “Short-term Sea Ice Gains Don’t Eliminate Long-term Threats.” Polar Bears International, “Scientists & Explorers Blog” posted 22 September 2014. http://www.polarbearsinternational.org/news-room/scientists-and-explorers-blog/short-term-sea-ice-gains-dont-eliminate-long-term-threats

Pilfold, N. W., Derocher, A. E., Stirling, I. and Richardson, E. 2015 in press. Multi-temporal factors influence predation for polar bears in a changing climate. Oikos. http://onlinelibrary.wiley.com/doi/10.1111/oik.02000/abstract

Stirling, I. 1974. Midsummer observations on the behavior of wild polar bears (Ursus maritimus). Canadian Journal of Zoology 52: 1191-1198. http://www.nrcresearchpress.com/doi/abs/10.1139/z74-157#.VR2zaOFmwS4

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 http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2486.2012.02753.x/abstract

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

Tracking polar bears in the Beaufort Sea – March 2015 map

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Here is the March 2015 follow-up to my post on the July 2013 track map for female polar bears being followed by satellite in the Beaufort Sea by the US Geological Survey (USGS) – “Ten out of ten polar bears being tracked this summer in the Beaufort Sea are on the ice.”

putting_collar_on_polar_bear_slider_USGS

See that post for methods and other background on this topic, and some track maps from 2012 (also available at the USGS website here). The USGS track map for March 2015 is copied below.

Three out of eight female bears tagged in the Southern Beaufort Sea were in the Chukchi Sea subpopulation region during March – not surprising, many bears cross this “boundary.”

Figure 1. From original caption: “Movements of 8 satellite-tagged polar bears for the month of March, 2015. Polar bears were tagged in 2014 on the spring-time sea ice of the southern Beaufort Sea. All eight of these bears have satellite collar transmitters.” Ice map for 30 March, 2015.  Original here.

Figure 1. From original caption: “Movements of 8 satellite-tagged polar bears for the month of March, 2015. Polar bears were tagged in 2014 on the spring-time sea ice of the southern Beaufort Sea. All eight of these bears have satellite collar transmitters.” Ice map for 30 March, 2015. Original here.

Note that the circles with the polar bear icons are the end points (final positions for the month), while the tail ends of the strings are the positions at the first of the month.

See last month’s map is copied below, discussed here.

Movements of 7 satellite-tagged polar bears for the month of February, 2015. Polar bears were tagged in 2014 on the spring-time sea ice of the southern Beaufort Sea. All seven of these bears have satellite collar transmitters. The teal-green track was not present in January. Polar bear satellite telemetry data are shown with AMSR2 remotely-sensed ice coverage for 28 February, 2015.

Figure 2. Movements of 7 satellite-tagged polar bears for the month of February, 2015. Polar bears were tagged in 2014 on the spring-time sea ice of the southern Beaufort Sea. All seven of these bears have satellite collar transmitters. The teal-green track was not present in January. Polar bear satellite telemetry data are shown with AMSR2 remotely-sensed ice coverage for 28 February, 2015. Click to enlarge. Original here.

Arctic sea ice extent total for March does not equal global polar bear habitat

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Only half or less of the estimated 2.6% loss per decade of March sea ice extent since 1979 (Fig. 1, below) represents a decline in polar habitat. That’s because several regions with sea ice that are not home to polar bears, like the Sea of Okhotsk, are included in Arctic sea ice totals.

Figure 1. Average monthly Arctic sea ice extent for March 1979-2015, which includes ice in the Sea of Okhotsk and the Sea of Japan, a decline of 2.6% per decade. NSIDC, March summary 2015.

Figure 1. Average monthly Arctic sea ice extent for March 1979-2015 (which includes ice in the Sea of Okhotsk, the Sea of Japan, and the Baltic, where polar bears do not live), shows a decline of 2.6% per decade. NSIDC, March summary 2015.

Both the Sea of Okhotsk and northern Sea of Japan (Fig. 2) have sea ice in winter (which is included in total Arctic sea ice records) but they are not truly “Arctic” – neither is connected to the Arctic by continuous ice, even when the ice is at its maximum extent (nor is the Baltic Sea — in contrast to Hudson Bay and the east coast of North America, which are connected to the Arctic by continuous ice).

Sea of Okhotsk_1979 March marked_PolarBearScience

Figure 2. Location of the Sea of Okhotsk and Sea of Japan. Insert ice map for March 1979 from NSIDC shows it’s position relative to the Arctic proper.

That lack of connection to Arctic pack ice is probably the main reason that polar bears never colonized the Sea of Okhotsk, even though western Arctic seal species (ringed, bearded, spotted, and ribbon) and Arctic whales  (bowhead and beluga) live there. Polar bears don’t currently live in the Sea of Okhotsk and all evidence suggests they never have.

Sea ice maps show that about half of the total ice extent difference between March 1979 and March 2015 was due to a relatively large decline in sea ice cover for Sea of Okhotsk and northern Sea of Japan — regions without polar bears. Surely no reputable scientist or journalist would suggest that the “record low” maximum ice extent for 2015 has any relevance for polar bear health and survival? [or for Northwest Passage travel, for that matter] Sadly, they would.


The Sea of Okhotsk covers 1.58 million kilometres squared (mkm2) – it’s a huge basin that was virtually filled with ice in March 1979 but only about 1/3 filled in 2015.

Detailed figures of ice cover, provided by NSIDC’s MASIE analysis since 2006, shows the ice extent for the Sea of Okhotsk in March 2006 was only 0.59 mkm21 — a large decline from its maximum extent in 1979.

However, Fig. 3 (below) shows that there was even less ice in the Sea of Okhotsk in 2015 than there was in 2006. I estimate that in 2015, there was approximately 0.5 mkm2 of sea ice in the Sea of Okhotsk and northern Sea of Japan combined (precise MASIE data is not available for 2015, but looks most like MASIE maps for 20091).

Figure 2. Arctic sea ice extent and concentration for 2015 and 2006 compared, courtesy NSIDC. Note that there was less ice in the Sea of Okhotsk in 2015 than in 2006, where MASIE archives show ice covered 0.59 mkm2. Click to enlarge.

Figure 3. Arctic sea ice extent and concentration for 2015 and 2006 compared, courtesy NSIDC. Note that there was less ice in the Sea of Okhotsk in 2015 than in 2006, where MASIE archives show ice covered 0.59 mkm2. Click to enlarge.

Here’s the math for the estimated contribution of Sea of Okhotsk ice to total Arctic ice extent for March:
total extent 1979 (period high), 16.5 mkm2
total extent 2015 (period low),  14.4 mkm2.

The difference between them is 2.1 mkm2, of which approximately 1.1 mkm2 represents the change in ice cover in the Sea of Okhotsk and Sea of Japan between 1979 and 2015 (Fig. 4).

Figure 3. Comparing sea ice extent over the Sea of Okhotsk and northern Sea of Japan for 1979 and 2015 (extents approximate).

Figure 4. Comparing sea ice extent over the Sea of Okhotsk and northern Sea of Japan for 1979 and 2015 (extents approximate).

Since polar bears do not live in the Sea of Okhotsk, it would therefore be totally disingenuous for a polar bear researcher, journalist, or conservation organization to state or imply that the “record low” maximum ice extent this year has any relevance for polar bear health or survival. But activist organization Polar Bears International recently did just that and so did polar bear biologist Andrew Derocher.

Did they just not think — or were they deliberately misleading the public?

Arctic sea ice extent total for March > (≠) global polar bear habitat.

In fact, I suggest that if ice extent figures for the Sea of Okhotsk, Sea of Japan and the Baltic Sea were removed from “Arctic” ice extent totals for the satellite record, we would find that total polar bear habitat at the end of March since 1979 has been about 15.0 mkm2 with relatively little variation over time.

And as I explained in my last post, polar bear habitat this spring is abundant.

Footnote 1: Sea ice extent totals at the end of March for Sea of Okhotsk (from NSIDC MASIE analysis archives) since 2006, the first available date, are given below. It is not clear if the extent totals given include ice in the northern Sea of Japan but they might.

2006 – 0.59 mkm2 (here, see below)

masie_all_r14_v01_2006090_4km

2007 – 0.8 mkm2 (here)
2008 – 0.68 mkm2 (here)
2009 – 0.51 (here and here, averaged)
2010 – 1.0 mkm2 (here)
2011 – 0.98 mkm2 (here)
2012 – 1.2 mkm2 (here, see below)

masie_all_r14_v01_2012091_4km

2013 – 1.0 mkm2 (here)
2014 – 0.83 mkm2 (here)
2015 ~0.51 mkm2 (MASIE not available, but NSIDC map below suggest extent was most like 2009)

2015 March

Challenging polar bear fearmongering about Arctic sea ice extent for March 2015

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Here are some facts to counter the misinformation and fearmongering being spread via twitter by a polar bear biologist who is getting carried away with his conservation activism.

Arctic Sea ice extent March greater than PB habitat_April 12 2015

Following up on my last post, I note that Arctic regions with sea ice but not polar bears were about 0.32 mkm2 below last year’s March average extent – which means the total ice decline from 2014 (0.4 mkm2) represents only a slight decline in polar bear habitat, most of which is in the Barents Sea (and due primarily to the state of the AMO, not global warming).

Sea ice extent for the Sea of Okhotsk and Baltic Sea combined (both areas without polar bears)1 were about 0.6 mkm2 below average this year for March. Average extent for March (according to NSIDC) is 15.5 mkm2, which means this year’s extent (14.4 mkm2) was 1.1 mkm2 below average, of which less than half (0.5 mkm2) was “lost” polar bear habitat.

IUCN Polar Bear Specialist Group biologist Andrew Derocher has been saying this is a “huge loss for polar bears” (see below): rational analysis of the facts show it is not.

Derocher tweet 2015 April 10_re March seaice and PB habitat

In fact, the area of polar bear habitat decline from average in March 2015 was about the size of Spain alone (~0.5 mkm2) and most of that was a predictable loss of Barents Sea ice, which has in recent years been strongly impacted by the negative state of the AMO. That’s meant a few challenges for Barents Sea polar bears but it’s nothing they haven’t experienced before and most bears seem to be adapting.

Derocher’s attempt to spread misinformation about the 2015 record low March extent in relation to polar bear habitat was the second within a week — it followed on the heals of another tweet he sent a few days earlier (copied below), which I countered here:

Derocher tweet 2015 April 7 claims March ice is polar bear habitat

Footnote 1. Area of sea ice without bears:
Area of Baltic Sea = 0.40 mkm2 [last froze over entirely in 1987]
Area of Sea of Okhotsk = 1.6 mkm2 [last froze over entirely in 1979]

Polar bear season for Newfoundland residents still going strong, recent sightings confirm

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Two recent sightings of polar bears along the north shore of Newfoundland are a reminder that sea ice is still a prominent feature of the Davis Strait polar bear subpopulation landscape at this time of year.

LaScie_Newfoundland_April 27 2015_ColleenGray label

A polar bear was sighted in the community of La Scie, northern Newfoundland Monday, 27 April (pictured above, swimming in the harbour), while another landed in the town of Fogo, on Fogo Island, last week (see maps below).

LaScie and Fogo Island Newfoundland locations

Locations of the April 2015 polar bear sightings. Click to enlarge.

CBC news reported this morning what might be the first polar bear sighting recorded for the community of La Scie, Newfoundland on Monday, 27 April 2015 (“Possible first polar bear sighting for La Scie”):

“Colleen Gray saw an unusual sight on Monday [April 27] when a polar bear strolled into her hometown of La Scie on the Baie Verte Peninsula.

She said some people saw the animal walking from the street and then into the harbour. Gray’s husband then used a boat to try and chase the bear out to sea.”

Colleen Gray posted several photos of the bear swimming on her Facebook page, reproduced in the CBC report, one included here (above).

La Scie Newfoundland, from the town website.

La Scie Newfoundland, from the town website.

Last week, the polar bear news was further east on Fogo Island
VOCM news had a brief report 24 April 2015 (“Polar Bear Spotted Wandering Around Fogo”), with a photo (although it is not clear if this was a photo of the bear itself or one from a previous sighting, no attribution given):

Photo from VOCM news report.

Photo from VOCM news report.

“Residents of Fogo Island are being made aware of an unexpected visitor in the area.

A polar bear was spotted in Fogo Centre last night [April 23] at around 7:00. Although sightings of polar bears are not uncommon at this time of year, RCMP remind residents to stay vigilant.”

CBC news picked it up later that day, with an eyewitness account (“Big shaggy dog’ spotted on Fogo Island turns out to be polar bear”):

“Clayton Waterman says he first spotted a young polar bear (like this one pictured) on the road in Fogo Island. Later the same bear was seen outside his home near Deep Bay. (CBC)

Some people on living on Fogo Island, off Newfoundland’s northeast coast, may be looking over their shoulders today after a polar bear was spotted lumbering around the community.

Clayton Waterman, 58, and his wife Doreen were on their way from Deep Bay to buy seal meat in the neighbouring community Tilting and decided to make the trip into Fogo to stop at the bank.

Waterman made a turn on the road by the hospital, near the local school, when they saw an animal walking on the road ahead of them.

“As we were going up the hill I noticed an animal on the road and I said, ‘Doreen, look at the big shaggy dog,’ and we were looking at it and as it got closer I said, ‘Doreen, my God, that’s a polar bear,'” said Waterman.

The bear was walking ahead of the Waterman’s vehicle headed in the same direction, Waterman said, so he continued to slowly drive behind it at a distance.

“It was just lumbering along on the pavement.”

‘I told Doreen to sleep on the couch just in case [the bear] came in he could see her first … just joking with her, right? But she didn’t like the joke.’- Clayton Waterman

According to Waterman, the bear was likely young and didn’t look to weigh any more than 250 pounds, but otherwise seemed to be healthy.”

Read the rest of the story here.

Fogo, Fogo Island, Newfoundland. From the town website.

Fogo, Fogo Island, Newfoundland. From the town website. Click to enlarge.

There was still plenty of sea ice north of the Newfoundland coast at the time of the sightings, as sea ice maps from the Canadian Ice Service below show (click to enlarge):

Newfoundland sea ice conditions at 25 and 27 April 2015

Related posts about Newfoundland and Labrador spring polar bear sightings and sea ice conditions:

Polar bear visiting Hibernia oil platform off Newfoundland was not far from sea ice March 23, 2015

Spring ice alarm deflated – 2015 ice now as high as 2014 & Davis Strait highest since 1971 April 16, 2015

Of Labrador polar bears and sea ice way above normal off Newfoundland [polar bears in Black Tickle, Labrador] March 4, 2014

Labrador polar bears face a longer ice-free season than Hudson Bay bears, but do well November 26, 2014

Snow depth over spring sea ice affects polar bear feeding success and ringed seal survival

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Snow depth over sea ice in spring affects the hunting success of polar bears on ringed seal (Phoca hispida) pups, but the relationship is more complicated than you might think and there is less data on this phenomenon than you would believe.

Ringed seal lair_snow and ice thickness_PolarBearScience_sm

Regional snow depth in spring (April-May) varies naturally from year to year due to weather patterns driven in part by long-term climate cycles (like the Atlantic Multidecadal Oscillation, Pacific Decadal Oscillation, and the Arctic Oscillation).

This year, it was very cold in Eastern North America, with record-breaking snow fall in some areas. Snow depth was apparently greater than average over Hudson Bay sea ice this spring but was it deep enough to have impaired polar bear hunting success?

Figure 1. Adult Barents Sea ringed seal, Norwegian Polar Institute, Kit Kovacs photo.

Figure 1. Barents Sea ringed seal, Norwegian Polar Institute, Kit Kovacs photo.

Deep snow over birthing lairs (diagram above, see also Lydersen and Gjerz 1986) means ringed seal pups are well protected from polar bear predation – the seals do well but the polar bears do not. For example, deep snow over ice was suspected to have negatively impacted the body condition of Western Hudson Bay polar bears in 1983, a year that Churchill had a spike in problem bears, bears in poor condition were documented, and cub survival was lower than average (Calvert et al. 1986:19, 24; Derocher and Stirling 1996:1247; Ramsay and Stirling 1988:627).

This conclusion is corroborated by the fact that in 1983, ringed seal researchers working in Western Hudson Bay (Ferguson et al. 2005) reported high mean snow depths in April-May (> 50cm). Onshore measurements had to be used as a proxy for on-ice snow depth, since there are no data for snow depth over sea ice on Hudson Bay.

Ferguson and colleagues instead used data from shore-based weather stations along the WHB coast for April-May (Ferguson et al. 2005:125):

“For snowfall, snow depth, and rainfall data, we averaged precipitation for five weather stations: Arviat, Chesterfield Inlet, Churchill, Coral Harbour, and Whale Cove.” [my bold]

The fact that spring mean snow depth of 50 cm or more was reported for four years in the 1960s, and one year in the 1970s (Ferguson et al. 2005:Fig. 2a) suggests that polar bear may have had an equally poor hunting success in those years as well – it just wasn’t documented, as far as I know. Deep snow in spring might be good news for ringed seals but it’s usually bad news for polar bears.

Shallow snow cover over birthing lairs, which are built against pressure ridges as shown in the diagram above (considered to be less than 25-32 cm over the lair, or less than 20 cm over flat ice),1 can mean the snow caves are easier for polar bears to break into (and consume the pup) – that’s good news for polar bears (in the short term) but bad news for ringed seals.

Mean snow depth was reportedly at or below the critical 20 cm threshold in April-May in Western Hudson Bay once in the 1960s and eight times between 1993 and 2000 (Ferguson et al. 2005: Fig. 2a).

There is an added risk for ringed seal snow caves with little snow cover – they can collapse if there is a warm spell (made worse by rain), although this can occur when snow depth is average or even above average (Stirling and Smith 2004:61). Lair collapse (or snow made soft by spring rain) leaves pups especially vulnerable to predation, which was documented off the coast of southeastern Baffin Island in April 1979 (Stirling and Derocher 2012:2700; Stirling and Smith 2004; Hammill and Smith 1991).

Lair collapse in early spring (March/April, depending on location), just after the pups are born, could also leave newborns (Fig. 2) at risk for death by hyperthermia, although this phenomenon has so far not been documented as being a significant risk over and above increased predation.

Figure 3. Newborn Barents Sea ringed seal with its white natal coat. Norwegian Polar Institute,Bjorn Frantzen photo.

Figure 2. Newborn Barents Sea ringed seal with its white natal coat. Norwegian Polar Institute,Bjorn Frantzen photo. See ringed seal life history details here, copied below.2

Unfortunately, several bad years for ringed seal pup survival caused by shallow snow depth in spring means that in subsequent years, fewer seal pups will be produced for polar bears to eat – polar bears end up suffering after a bit of a lag.

Shallow snow depths in the 1980s (Ferguson et al. 2005: Fig. 2a) seem to have been the cause of the marked decline in Western Hudson Bay polar bear numbers documented between 1989 and 1990 (Derocher and Stirling 1996; Lunn et al. 2013), while thick ice in 1991 (Chambellant et al. 2012:274) contributed to a continued decline (Fig. 3, below).

Figure 1. This is Fig. 8 from Lunn et al. (2013), the most recent report on the estimated size of the Western Hudson Bay polar bear population.

Figure 3. This is Fig. 8 from Lunn et al. (2013), the most recent report on the estimated size of the Western Hudson Bay polar bear population. Click to enlarge.

Snow depth over sea ice data
You might be surprised to find out how few data on snow depth over sea ice exists (i.e., actual observations or measurements), apart from measurements that ringed seal researchers have collected.

This year, weather records show that snow depth in mid-April was >30 cm over Hudson Bay but how much greater may not be recorded (Fig. 4, below):

Figure 2. Snow depth over North America, including Hudson Bay, at 25 April 2015. Courtesy The Weather Network.

Figure 4. Snow depth over North America, including Hudson Bay, at 25 April 2015. Courtesy The Weather Network. Click to enlarge.

See also the Sea Surface Temperature Anomalies, Ice and Snow Cover, 1 year animation, from Environment Canada, for snow depth records over the last 365 days that include Hudson Bay.

But what about historical records? Surprisingly, there isn’t much.

One study (Warren et al. 1999) took measurements of snow depth over 37 years, between 1954 and 1991, in the central Arctic Basin over multiyear ice only. Since polar bears and ringed seals prefer annual ice over continental shelves for hunting in spring, this data is not especially useful.

Kwok et al. 2011 measured snow depth from the air in April 2009, via microwave radar, along several Arctic tracks that included a transect from the Alaskan shore through annual ice in the Beaufort Sea, several through multiyear ice and one through mixed annual plus multiyear ice. However, this technique worked only over smooth sea ice.

Nevertheless, the authors found that smooth ice snow depth over annual ice was above the critical threshold of 20 cm suggested by ringed seal studies:

“In early April, mean snow depths are 28.5 ± 16.6 cm and 41.0 ± 22.2 cm over first‐year and multiyear sea ice (MYI), respectively.”

There are important implications of this poor record of snow depth observations over sea ice for predicting future conditions.

Hezel and colleagues (2012), who developed a model to project April snow depths into the 21st century to see how ringed seals might be affected by global warming, used simulated data generated by other models developed by the Climate Model Intercomparison Project (CMIP5; explained in Taylor et al. 2012); Hudson Bay, Foxe Basin and Davis Strait regions were not included in this analysis.

In other words, there were so few archived observations of snow depth over sea ice across the range of ringed seals that they had to be made up by a computer model – and even then, the models could not be applied across the entire species range.

Yet, this analysis played a large role in the 2012 US Fish and Wildlife Service listing of ringed seals as ‘threatened’ with extinction (USFWS 2012a). (see previous posts here and here).

In addition, it is apparent that there could have been no expectation by Hezel and colleagues that their predictions of snow depth over sea ice changes in the 21st century would ever be validated by observations, given that so few actual measurements of snow depth have been taken so far.

Conclusions
Early ice breakup in summer and/or late freeze-up in fall cannot exclusively be blamed when polar bears struggle to get through the ice-free period. Snow depth over sea ice is also a factor, but one that is very difficult to document.

As a result of snow depth variations, polar bear hunting success and cub survival can fluctuate rather dramatically, which in turn can cause the subpopulation size to fluctuate as well.

Therefore, due to entirely natural variations in spring snow conditions over sea ice (and thickness of the ice),2 polar bear population sizes can vary by region. This natural variation in population size is seldom mentioned by those who rush to blame all polar bear subpopulation declines on recent increases in the open water season.

Regarding Hudson Bay bears, we probably won’t know until later in the summer if they were affected by deep snow and/or thick sea ice this spring. Once the bears are onshore this summer, the body condition of most bears will tell us if they were well-fed over the spring or not (of course, some bears will be in average or poor condition every year because they are inexperienced hunters, too old to defend their kills, or simply ran into bad luck). This will be especially apparent if breakup is not particularly early – but we’ll have to wait and see.

Footnote 1. Smith and Stirling (1975:1299) found that the minimum snow depth over birth lairs in the Eastern Beaufort in 1971-1974 was about 20 cm, while Ferguson et al. (2005) found that the critical depth in Western Hudson Bay was 32 cm.

Footnote 2. Birthing success of female ringed seals (Phoca hispida) is also affected by regional sea ice thickness in early spring. For example, in the eastern Beaufort Sea, repeated bouts of thick spring ice, lasting 2-3 years out of every 10 years or so since the 1960s, have occurred. It appears that pregnant ringed seals abandon traditional near shore pupping areas because the ice is too thick to maintain breathing holes. When these conditions occurred, polar bear females with new cubs (as well as young bears on their own) had difficulty finding enough to eat – without a bumper crop of fat young ringed seals to consume, they didn’t have enough fat to see them through the rest of the year. Many females lost most or all of their cubs.

A similar but somewhat less devastating phenomenon affected Western Hudson Bay ringed seals and polar bears in 1991, which was a very cold year in Eastern Canada (Chambellant et al. 2012:274). It was very cold in 1992 as well – however, polar bears apparently compensated for the reduced number of seals available by staying on the sea ice and hunting for an extended period of time, which was possible because breakup was very late that year.

References
Calvert, W., Stirling, I., Schweinsburg, R.E., Lee, L.J., Kolenosky, G.B., Shoesmith, M., Smith, B., Crete, M. and Luttich, S. 1986. Polar bear management in Canada 1982-84. In: Polar Bears: Proceedings of the 9th meeting of the Polar Bear Specialists Group IUCN/SSC, 9-11 August, 1985, Edmonton, Canada. Anonymous (eds). Gland, Switzerland and Cambridge UK, IUCN. http://pbsg.npolar.no/en/meetings/ pg. 19-34.

Chambellant, M., Stirling, I., Gough, W.A. and Ferguson, S.H. 2012. Temporal variations in Hudson Bay ringed seal (Phoca hispida) life-history parameters in relation to environment. Journal of Mammalogy 93:267-281.

Derocher, A.E. and Stirling, I. 1996. Aspects of survival in juvenile polar bears. Canadian Journal of Zoology 73:1246-1252.

Ferguson, S.H., Stirling, I., and McLoughlin, P. 2005. Climate change and ringed seal (Phoca hispida) recruitment in Western Hudson Bay. Marine Mammal Science 21:121-135.

Hammill, M.O. and Smith T.G. 1991. The role of predation in the ecology of the ringed seal in Barrow Strait, Northwest Territories, Canada. Marine Mammal Science 7:123–135.

Hezel, P.J., Zhang,X., Bitz, C.M., Kelly,B.P., and Massonnet, F. 2012. Projected decline in spring snow depth on Arctic sea ice caused by progressively later autumn open ocean freeze-up this century. Geophysical Research Letters 39, L17505, doi:10.1029/2012GL052794.

Kwok, R., Panzer, B., Leuschen, C., Pang, S., Markus, T., Holt, B. and Gogineni, S. 2011. Airborne surveys of snow depth over Arctic sea ice. Journal of Geophysical Research 116, C11018, doi:10.1029/2011JC007371.

Lunn, N.J., Regehr, E.V., Servanty, S., Converse, S., Richardson, E. and Stirling, I. 2013. Demography and population assessment of polar bears in Western Hudson Bay, Canada. Environment Canada Research Report. 26 November 2013. PDF HERE

Lydersen, C. and Gjertz, I. 1986. Studies of the ringed seal (Phoca hispida Schreber 1775) in its breeding habitat in Kongsfjorden, Svalbard. Polar Research 4:57-63. Open access. http://www.polarresearch.net/index.php/polar/article/viewFile/6920/7753 [contains a copy of the birthing lair graphic modified at the beginning of this post, originally produced in “Gjertz, I. and Lydersen, C. (1983). Pupping in ringed seals in Svalbard. Fauna, 36, 65-66 (in Norwegian)” and reproduced in colour (with permission) by GRID Arendal (original graphic here).

Ramsay, M.A. and Stirling, I. 1988. Reproductive biology and ecology of female polar bears (Ursus maritimus). Journal of Zoology London 214:601-624. http://onlinelibrary.wiley.com/doi/10.1111/j.1469-7998.1988.tb03762.x/abstract

Smith, T.G. and Stirling, I. 1975. The breeding habitat of the ringed seal (Phoca hispida): the birth lair and associated structures. Canadian Journal of Zoology 53:1297-1305.

Stirling, I. and Derocher, A.E. 2012. Effects of climate warming on polar bears: a review of the evidence. Global Change Biology 18(9):2694-2706. http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2486.2012.02753.x/abstract [paywalled]

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  Open access.

Stirling, I. and Parkinson, C.L. 2006. Possible effects of climate warming on selected populations of polar bears (Ursus maritimus) in the Canadian Arctic. Arctic 59:261-275. http://arctic.synergiesprairies.ca/arctic/index.php/arctic/issue/view/16  Open access.

Stirling, I. and Smith, T.G. 2004. Implications of warm temperatures and an unusual rain event for the survival of ringed seals on the coast of southeastern Baffin Island. Arctic 57:59–67. http://arctic.journalhosting.ucalgary.ca/arctic/index.php/arctic/article/view/483   Open access. See abstract below:

We recorded an unusually warm period in early April 1979 along the coastline at the end of the Hall Peninsula on southeastern Baffin Island, Nunavut. Maximum temperatures remained at or above freezing for almost a week, and rain fell on our field camp on three consecutive days. In contrast, meteorological data collected from three nearby coastal stations (Brevoort Island, Cape Dyer, and Resolution Island) between 1950 and 1992 indicated that the mean minimum and maximum air temperatures for the month of April are normally 10-20°C cooler than the averages we recorded at our camp. Periodic warming to near freezing, probably due to the maritime influence of nearby open water in Davis Strait, occurs in this area in late March and early April, but not usually to the degree we observed. Between 1950 and 1992, additional similar rain events were recorded only twice at the coastal weather stations. In late March, we found slumped roofs over some ringed seal (Phoca hispida) birth lairs and others that had collapsed, probably because of four days of weather only slightly below freezing and heat generated by seals within the lairs. After the rain in April, we found subnivean lairs with melted roofs, and several snowdrifts that had previously contained lairs were completely washed away. Newborn pups were left lying on the bare ice, subject to thermoregulatory stress and vulnerable to significantly increased predation by polar bears (Ursus maritimus) and arctic foxes (Alopex lagopus). If the climate continues to warm in the Arctic, as is predicted, it is likely that rain will be more widespread during early spring. If that occurs, the premature removal of protection offered by subnivean birth lairs may expose young ringed seal pups to high levels of predation, which may negatively affect populations of ringed seals and the polar bears that depend on them for food.

Taylor, K.E., Stouffer, R.J. and Meehl, G.A. 2012. An overview of CMIP5 and the experiment design. Bulletin of the American Meteorological Society 93(4):485-498.

US Fish and Wildlife Service. 2012a. Threatened status for the Arctic, Okhotsk and Baltic subspecies of the ringed seal. Federal Register 77(249):76706-76738.

Warren, S. G., Rigor, I.G., Untersteiner, N., Radionov, V.F., Bryazgin, N.N., Aleksandrov, Y.I., and Colony, R. 1999. Snow depth on Arctic sea ice. Journal of Climate 12:1814–1829.

Beaufort Sea polynyas open two weeks before 1975 – open water is good news for polar bears

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With masses of very thick, multiyear ice off Alaska this spring, the developing polynyas (open water) at either end of the Beaufort Sea are providing essential polar bear hunting habitat.

SB polynyas on ice thickness map 14 May 2015_PolarBearScience

Patches of open water in the Beaufort Sea are naturally recurring phenomena. This year we have two excellent examples, shown by the yellow arrows in the sea ice thickness map above (from the Naval Research Laboratory).

The eastern-most polynya forms in the Canadian portion of the Beaufort most years in the spring. This open water feature is so common it has a name – the Cape Bathurst polynya. Last year, there wasn’t an obvious polynya there until sometime in June, but in 1975, a patch of open water almost as large (or larger) as this year’s had developed by the end of May (Fig. 1).

Figure 1. Cape Bathurst polynya at 28 May 1975 (Smith and Rigby 1981: Fig. 14h), with the extent probably underestimated, and the polynya this year at 14 May (Canadian Ice Service). Click to enlarge.

Figure 1. Cape Bathurst polynya at 28 May 1975 (Smith and Rigby 1981:Fig. 14h) and the polynya this year at 14 May (Canadian Ice Service). See discussion in the text below about the relative sizes. Click to enlarge.

According to the experts that study them, the timing and extent of the polynya formation depends on wind (Dunbar 1981:29), not temperature. This means that this spring’s polynya formation in the eastern Beaufort isn’t a symptom of global warming, it isn’t missing polar bear habitat,” and it isn’t a sign of early sea ice breakup.

In fact, the Cape Bathurst polynya is a critical place for ringed seals and bearded seals to congregate in spring. Therefore, this is where many Southern Beaufort polar bears go to hunt. The presence of the polynya is especially crucial in years like this one, when very thick sea ice covers most of the Beaufort Sea. 

Cape Bathurst polynya
A little-known edited volume published by the Canadian Wildlife Service almost 35 years ago (Stirling and Cleator 1981) outlined the state of Canada’s Arctic polynyas between 1975 and 1979, provided an overview of why these open water features are so important to the ecology of the Arctic. It provides some much-needed historical perspective on the area of open water that appeared this year in late April in the eastern Beaufort.

A paper by Smith and Rigby contains maps that show conditions as they developed in May 1975 (Fig. 1 above and Fig. 2 below). The ice data they had to work with at the time appear to have underestimated the extent of open water, as I discuss below, but the location and timing compare well with this year’s polynya.

Here is what Smith and Rigby (1981:24) had to say about the development of open water in eastern Beaufort in the spring:

“Some open water can be found in virtually all months somewhere in western Amundsen Gulf in the area of Cape Bathurst, Cape Parry, and Cape Kellet (Banks Island). Open water can appear as early as sometime in December, although it is not until April that a characteristic form to the polynya appears.

During each of the 5 years [of the study: 1975-1979] an open lead developed off the eastern side of Cape Bathurst sometime in January (Fig.14a). This coincided with the appearance of open water just north of Cape Parry in 4 of the 5 years. Open water remains in the general area, in some form, until late May to early June when, characteristically, the area between Cape Bathurst and Cape Kellett opens up to form a disintegration area. Until April, the size, shape, and location of open water is quite variable by month and by year (e. g. Fig. 14b). By April in most years, however, the polynya exhibits a more or less typical form (Fig. l4(c-f). With the advance of break-up, the open water between Cape Bathurst and Cape Kellett enlarges into Amundsen Gulf. In addition, open water develops northwards, along Banks Island, and westwards to Mackenzie Bay (see Fig. 14g. h). The extent to which the shorelead polynya system in the Beaufort Sea is open is mainly dependent upon wind since this influences the movement of the Arctic pack. The coast was open to Mackenzie Bay in all five summers, and as far west as Barter Island in three.” [my bold]

West of Cape Barrow polynya
It may surprise you to learn that there is also a patch of open water off the western end of the Alaska coast near Barrow, which shows up in the Beaufort Sea ice concentration map below (Fig. 2). That polynya is not unusual either.

Figure 2. West Barrow polynya at 17 May 1975 (Smith and Rigby 1981: Fig. 15c) and the polynya this year at 14 May (Naval Research Laboratory). Click to enlarge.

Figure 2. West Barrow polynya at 17 May 1975 (Smith and Rigby 1981:Fig. 15c) and the polynya this year at 14 May (Naval Research Laboratory). Click to enlarge.

Back in 1975, a polynya had formed west of Point Barrow as well. As researchers Smith and Rigby (1981:24) pointed out, based on records from the early 1970s, this polynya usually became prominent about this time of year:

“In contrast to the region discussed above, sizeable areas of open water rarely occur between Mackenzie Bay [mouth of the Mackenzie River] and Point Barrow for any length of lime during the winter. The lead along this part of the coast tends to remain closed. In the area west of Point Barrow, however, open water and new ice is evident in most months, but again, it does not become continuous and extensive until about mid May.

Break-up, which is characterized by progressive widening of the lead system, usually commences in mid June (except mid May in 1979). As break-up progresses, a narrow continuous lead develops along the whole coast from Cape Bathurst to Point Barrow, with the region between Mackenzie Bay and Point Barrow being the last to open.” [my bold]

And here is what marine mammal biologists Ian Stirling and colleagues had to say about polar bears and the Cape Bathurst polynya in spring (Stirling et al. 1981:49):

Polar bears prey mainly upon ringed seals and, to a lesser degree, on bearded seals. Polar bears appear to be more abundant in polynya areas and along shoreleads, probably because the densities of seals are greater and they are more assessable. For example, between March and June in the Beaufort Sea from 1971 through 1975, 87% of the sightings of polar bears were made adjacent to floe edges or in unstable areas of 9/10 or 10/10 ice cover with intermittent patches of young ice.” [my bold]

Later, they discussed why these areas of open water can be so important in the Southern Beaufort area (Stirling et al. 1981:54):

“One useful approach is to ask what would happen if the polynya was not there? Obviously this is impossible to evaluate on an experimental basis, but by examining the consequences or natural seasonal variation, some useful insights can be gained. For example, the influence of rapidly changing ice conditions on the availability of open water, and consequently on populations of seals and polar bears, has been observed in the western Arctic. Apparently in response to severe ice conditions in the Beaufort Sea during winter 1973-74, and to a lesser degree in winter 1974-75, numbers of ringed and bearded seals dropped by about 50% and productivity by about 90%. Concomitantly, numbers and productivity of polar bears declined markedly because of the reduction in the abundance of their prey species. …If the shoreleads of the western Arctic or Hudson Bay ceased opening during winter and spring, the effect on marine mammals would be devastating.”[my bold]

In other words, Stirling and colleagues suggested in 1981 that the marked declines in ringed seal, bearded seal and polar bear numbers in the mid-1970s (discussed many times on this blog) was due primarily to the fact that the Cape Bathurst polynya did not develop as usual because thick ice conditions prevented it.

[See previous posts here, here, here and here]

All in all, considering how much thick, multiyear ice there has been in the Southern Beaufort this year since early April (Figs. 3 and 4 below), it seems to me that polar bears are very lucky that the Cape Bathurst polynya developed a bit earlier than usual this year.

Figure 3. Ice thickness map from the Naval Research Laboratory for 14 May 2015.

Figure 3. Ice thickness map from the Naval Research Laboratory for 14 May 2015.

Figure 4. Ice thickness map from the Naval Research Laboratory for 8 April 2015.

Figure 4. Ice thickness map from the Naval Research Laboratory for 8 April 2015.

Watch the ice thickness conditions develop over the winter in the NRL animation below, remembering that green, yellow, red, and black show multiyear ice (from the Naval Research Laboratory ):

Sea ice coverage as a proxy for polynya size
The Canadian Ice Service (CIS) weekly graphs for historical ice coverage in the Beaufort Sea (Fig. 5, below) show that sea ice this year is slightly below average for this date (14 May) but not as low as virtually every year from 1968 to 1979 (only 1968 and 1974 had average ice levels).

Without polynyas and extensive shoreleads, the Beaufort Sea is nearly 100% ice covered in late winter and spring. When ice coverage is not close to 100% at this time of year, it indicates not only the presence of polynyas, but their relative size.

Take a look at the value for 1975 in Fig 5 (below), the year the Smith and Rigby maps featured in Figs. 1 and 2 were constructed (using different sea ice data). CIS attributes 1975 with an ice coverage of about 86-87%, well below the level seen this year, which has about 93% ice coverage. That suggests to me that the 1975 polynya may have been as large as this year’s, or even larger.

Figure 5. Ice cover in the Beaufort Sea for the week of 14 May, 1968-2015, using Canadian Ice Service data. Click to enlarge.

Figure 5. Ice cover in the Beaufort Sea for the week of 14 May, 1968-2015, using Canadian Ice Service data. Click to enlarge.

Conclusion
The areas of open water in the eastern Beaufort and west of Point Barrow that are obvious in Beaufort Sea ice maps for early to mid-May are not unusual, not as large as they have been in the past, and are beneficial to polar bears and their prey. Given the amount of thick, multiyear ice present along the north slope of Alaska and in the offshore region, polar bears are very lucky that these polynyas developed when they did.

References
Dunbar, M.J. 1981. Physical causes and biological significance of polynyas and other open water in sea ice. In: Polynyas in the Canadian Arctic, Stirling, I. and Cleator, H. (eds), pg. 29-43. Canadian Wildlife Service, Occasional Paper No. 45. Ottawa.

Stirling, I. and Cleator, H. (eds). 1981. Polynyas in the Canadian Arctic. Canadian Wildlife Service, Occasional Paper No. 45. Ottawa.

Smith, M. and Rigby, B. 1981. Distribution of polynyas in the Canadian Arctic. In: Polynyas in the Canadian Arctic, Stirling, I. and Cleator, H. (eds), pg. 7-28. Canadian Wildlife Service, Occasional Paper No. 45. Ottawa.

Stirling, I, Cleator, H. and Smith, T.G. 1981. Marine mammals. In: Polynyas in the Canadian Arctic, Stirling, I. and Cleator, H. (eds), pg. 45-58. Canadian Wildlife Service, Occasional Paper No. 45. Ottawa.

Pdf of pertinent excerpts of above papers here.


Polar bear habitat update: Hudson Bay sea ice breakup on track

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Hudson Bay sea ice coverage is only slightly below average for this time of year (week of 14 May, below) but well above levels for 2006, when Western Hudson Bay breakup was relatively early).

Sea ice Canada 2015 May 14_CIS

Figure 1. Sea ice coverage over Hudson Bay for the week of 14 May, 1971-2015. Canadian Ice Service. Click to enlarge.

Figure 1. Sea ice coverage over Hudson Bay for the week of 14 May, 1971-2015. Canadian Ice Service. Click to enlarge.

Even at its highest extent in April, Hudson Bay is only 97-98% ice covered (due to persistent shoreleads and polynyas), which means ice levels are currently only 10% or so below maximum. In other words, there is still lots of polar bear hunting habitat over the bay.

That’s a bit lower than ice coverage was for the last two years at this date (2013-2014), which had average or above average ice cover. However, there is currently a bit more ice on Hudson Bay than there was in 2011 and 2012 – and much more than there was in 2010 and 2006.

Note that in mid-late May 2013 (Fig. 2), sea ice was breaking up in southwest Hudson Bay, around Churchill, as well as along the east coast.

The difference from 2015 is almost certainly due to currents and prevailing winds (known to drive the formation of spring polynyas, as discussed in my last post regarding open water in the Beaufort Sea), not temperature (Danielson 1990).

Figure 2. Sea ice coverage over Canada at 23 May 2013, showing patches of open water and/or low ice concentrations along the southwest coast of Hudson Bay, near Churchill (a bit south of where an opening occurs this year), and along the west coast.

Figure 2. Sea ice coverage over Canada at 23 May 2013, showing patches of open water and/or low ice concentrations along the southwest coast of Hudson Bay, near Churchill (a bit south of where an opening occurs this year), and along the west coast. Click to enlarge.

Breakup of sea ice over Hudson Bay usually proceeds from the east and north, with the last remaining ice converging on the southwest shore (Fig. 3, discussed previously here). The pattern and ultimate date of breakup is highly variable year to year (Fig. 5).

Figure 3. The peculiar pattern of ice melt on Hudson Bay is illustrated by this figure from Stirling et al. (2004). Ice along the southwest coast of Hudson Bay (darkest gray) is the last to melt each season. As a consequence, the southwest quadrant is where most Western Hudson Bay bears come ashore. Note that the “time of breakup” on this map uses the old, out-of-date method (50% ice coverage).

Figure 3. The peculiar pattern of ice melt on Hudson Bay is illustrated by this figure from Stirling et al. (2004). Ice along the southwest coast of Hudson Bay (darkest gray) is the last to melt each season. Note that the “time of breakup” on this map uses the old, out-of-date method (50% ice coverage). Click to enlarge. See previous discussion here.

Sea ice Canada 2015 May 18_CIS

Figure 4. Sea ice coverage over Canada at 18 May 2015. Not much has changed since last week (at 14 May, opening image above). Click to enlarge.

Figure 5. Hudson Bay breakup patterns for 17 May (Region 10, day 137) compared: 2015, 2011, 2009, 2010, 2007, 2006. NSIDC MAISE products archive. Note that 2009 had one of the latest breakup dates on record (30 July), while 2006 was relatively early (mid-June). Comparing the current year to only one previous year is uninformative because breakup patterns and dates are so variable year to year. Click to enlarge.

Figure 5. Hudson Bay breakup patterns for 17 May (Region 10, day 137) compared: 2015, 2011, 2009, 2010, 2007, 2006. NSIDC MAISE products archive. Note that 2009 had one of the latest breakup dates on record (30 July), while 2006 was relatively early (mid-June). Breakup patterns and dates are variable year to year. Click to enlarge.

References
Danielson Jr., E.W. 1990. Hudson Bay ice conditions. Arctic 24(2):90-107. pdf here.

Stirling, I., Lunn, N.J., Iacozza, J., Elliott, C., and Obbard, M. 2004. Polar bear distribution and abundance on the southwestern Hudson Bay coast during open water season, in relation to population trends and annual ice patterns. Arctic 57:15-26. http://arctic.synergiesprairies.ca/arctic/index.php/arctic/article/view/479/509

Arctic polynyas and sea ice extent in Canada at 20 May 2015

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The map of sea ice extent in Canada at 20 May 2015 is an almost-perfect example of the placement of recurring patches of open water polynyas that were present in the Canadian Arctic at this time of year in 1975-1979. Notes from field work on shore leads in Hudson Bay ice at May, 1948 offer further insight into the current pattern of sea ice cover on the bay.

Polynyas and shore leads vs sea ice at 20 May 2015_PolarBearScience

May is traditionally the time when recurring polynyas in the Canadian Arctic become more prominent and persistent shore leads (cracks in the ice near shore, also called “flaw leads”) become wider. Polar bears hunt around these polynyas because ringed and bearded seals congregate around them in the spring (Stirling et al. 1981; Stirling 1997). These polynyas are often not truly “open water” but covered by thin ice that’s easy for seals to break through.

Slight differences in location and size of polynyas and shore leads from year to year (especially in spring) are governed primarily by prevailing winds (Dunbar 1981:29) and to a lesser extent, currents. See my previous discussion on Beaufort Sea polynyas, with references: Beaufort Sea polynyas open two weeks before 1975 – open water is good news for polar bears.

This suggests that while sea ice cover over Hudson Bay and the Beaufort Sea is now a bit below average for this time of year (as the maps for this week show), it does not necessarily portend an earlier breakup or longer open-water period later in the year.

Dunbar (1981:32) had this to say about Hudson Bay’s persistent flaw leads:

“The largest flaw leads normally found in Canada are in Hudson Bay. The Hudson Bay lead, seaward of the fast ice, is so wide as to have generated the belief that the whole of the bay, except for the fast ice region along the shore, stayed unfrozen all winter…In the Hudson Bay instance, the myth of an open bay all winter was dispelled by Hare and Montgomery (1949), who showed that the pattern of of air temperatures over the whole region made an open Hudson Bay in winter very improbable. By overflying the area, they demonstrated that in fact the central bay is covered with ice in winter, although there normally exists a large flaw lead seaward of the fast ice on both sides of the bay and extending into northern James Bay. This flaw lead varies in width according to the direction of the wind from “about a mile and a half to 30 or 40 nautical miles” (Hare and Montgomery 1949).” [my bold]

Here is what Hare and Montgomery (1949:160, 163) said about Hudson Bay shore leads:

“The shore lead, which seems to have caused so much confusion in estimating the ice cover of Hudson Bay, may at times be entirely absent. Along the east coast from Great Whale River to Port Harrison the “Ice” reconnaissance of 8 March 1949 found no suggestion of open water. There were traces of old refrozen leads but none of them as large or as continuous as the one found along this same coast by the “Cariberg” reconnaissance of 6 May 1948. At that time the lane of open water off Port Harrison [now called Inukjuak, on the east coast] was 25 to 30 miles wide and seemed to stretch north and south along the coast as far as could be seen. It should be noted that this wide shore lead resulted after several days of NE winds which had effectively driven the ice offshore. [my bold]

In contrast, this year, the shore lead is expanding on the western side.

Arctic melt progress (click maps and graphs to enlarge)

For Canadian waters, courtesy Canadian Ice Service (see maps in red, top left corner, for area covered by the graphs) [compare to last week here]

East Coast (regional), week of 21 May (1969-2015) – about average.
Regional East Coast week of May 21 1968-2015 CIS

Davis Strait, week of 21 May (1969-2015), well above average.
Davis Strait same week May 21 1971-2015 CIS

Hudson Bay (regional), week of 21 May (1971-2015), just about average. Hudson Bay Regional same week May 21 1971-2015 CIS

Hudson Bay only, week of 21 May (1971-2015), slightly below average. Hudson Bay same week May 21 1971-2015 CIS

Beaufort Sea, week of 21 May (1968-2015), slightly below average. Beaufort Sea same week 21 May 1968_2015 with average_CIS

Sea ice extent and concentration for Barents Sea and East Greenland
Courtesy Norwegian Ice Service.

For 19 May 2015 – note the high ice concentration (red, “very close drift ice”) Barents Sea ice plus East Greenland 2015 May 19_NIS

Compare to 19 May 2014:
Barents Sea ice 2014_19 May_NIS

Compare to 19 May 2009:
Barents Sea ice 2009_19 May_NIS

Sea ice extent for the entire Arctic, at 19 May 2015, courtesy NSIDC MASIE
masie_all_zoom_v01_2015139_4km

Polynya map from Smith and Rigby 1981 below (click to enlarge):
Polynyas and shore leads_Smith and Rigby 1981

Sea ice map for Canada at 20 May 2015 (click to enlarge):
Sea ice Canada 2015 May 20_CIS

References
Dunbar, M.J. 1981. Physical causes and biological significance of polynyas and other open water in sea ice. In: Polynyas in the Canadian Arctic, Stirling, I. and Cleator, H. (eds), pg. 29-43. Canadian Wildlife Service, Occasional Paper No. 45. Ottawa.

Stirling, I. and Cleator, H. (eds). 1981. Polynyas in the Canadian Arctic. Canadian Wildlife Service, Occasional Paper No. 45. Ottawa.

Smith, M. and Rigby, B. 1981. Distribution of polynyas in the Canadian Arctic. In: Polynyas in the Canadian Arctic, Stirling, I. and Cleator, H. (eds), pg. 7-28. Canadian Wildlife Service, Occasional Paper No. 45. Ottawa.
Stirling, I, Cleator, H. and Smith, T.G. 1981. Marine mammals. In: Polynyas in the Canadian Arctic, Stirling, I. and Cleator, H. (eds), pg. 45-58. Canadian Wildlife Service, Occasional Paper No. 45. Ottawa.

[Pdf of pertinent excerpts of above papers here]

Hare, F.K. and Montgomery, M.R. 1949. Ice, Open Water, and Winter Climate in the Eastern Arctic of North America: Part II. Arctic 2(3):149-164. http://arctic.journalhosting.ucalgary.ca/arctic/index.php/arctic/article/view/3985 Pdf here.

[see also: Hare, F.K. and Montgomery, M.R. 1949. Ice, Open Water, and Winter Climate in the Eastern Arctic of North America: Part I. Arctic 2(2):79-89. http://arctic.journalhosting.ucalgary.ca/arctic/index.php/arctic/article/view/3976 ]

Stirling, I. 1997. The importance of polynyas, ice edges and leads to marine mammals and birds. Journal of Marine Systems 10:9-21.

Many polar bears cubs seen in Svalbard this year, says Norwegian biologist

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Good news from Norway: polar bears around Svalbard are in excellent condition this spring and many females with new cubs have been spotted. This is a marked turn around from conditions just last year.

 Roy Mangersnes / Wildphoto


Roy Mangersnes / Wildphoto

According to a Norwegian news outlet yesterday, Jon Aars (Fig. 1, below), from the Norwegian Polar Institute, confirms that this has been an excellent year for polar bear cubs around Svalbard because there has been abundant sea ice near denning areas on the east coast.

Figure 1. Biologist Jon Aars with a Svalbard cub.

Figure 1. Biologist Jon Aars with a Svalbard cub.

In an interview with Norwegian broadcaster Sigrid Agnethe Hansen (23 June 2015), polar bear biologist Jon Aars from the Norwegian Polar Institute said (via Google Translate and some inference on my part for a few words):

“Last year [2014] in autumn we saw that there was more ice, particularly in denning areas. And throughout the year the ice conditions have held up good… It has been an excellent year, with a lot of ice. It appears that there are many females in good condition that have cubs of the year, and the cubs appear to be in good shape…. Many of the females we saw this year had cubs, and it is natural to believe that the abundance of ice exerted a positive effect. It may be a little difficult to say they [the bears?] are completely safe, as we can not always explain all the variation we see. But it is safe to say [?], that a bad ice year can contribute to the reason why the count of cubs are poor [or low].” [my bold]

Read the whole thing here, in Norwegian [note “isår” is “ice year”; Google Translate offered me “Hungarians” for the word “ungar” which made for an amusing read until I figured out the right word was “cubs” – strictly speaking, “young ones” (as in, “mothers with cubs” rather than “mothers with Hungarians”). Many thanks to Bjorn L. for passing this along with a few translation tips]  More photos of Svalbard polar bears here.

Fig. 3 below shows sea ice maps for the fall of 2014 and the fall of 2013 (1 November). It is clear why most pregnant females apparently moved east to Franz Josef Land (discussed here) in the fall of 2013, where ice was more abundant – in 2013 there was no ice around the denning areas on the east coast of Svalbard. They had little choice but to go to Franz Josef Land or make their dens on the sea ice (as many females in the Barents Sea do on a regular basis).

Figure 2. Barents Sea ice coverage at 1 November 2013 (top) and 2014 (bottom). Click to enlarge.

Figure 2. Barents Sea ice coverage at 1 November 2013 (top) and 2014 (bottom). Click to enlarge.

That would explain why few females with cubs were seen in the spring of 2014 around Svalbard – most mothers pregnant with cubs had moved to Franz Josef Land, so that’s where the cubs would have been born. Based on interviews with Jon Aars, media outlets (e.g. the Guardian, 28 May 2014 and CBC, 29 May 2014) made this phenomenon sound like a catastrophe that could only get worse.

One short year later, it’s a completely different story with a very happy ending. The improved ice conditions over last year are almost certainly due to the recent change in state of the Atlantic Multidecadal Oscillation (AMO) [more here] with perhaps some influence from the newly-described Madden-Julian Oscillation (MJO), which tends to affect sea ice from November to January (Henderson et al. 2014).1

Such natural variations in sea ice conditions that occur outside the summer season (and which are strong enough to negatively affect local polar bear populations) are the topic of my recent Arctic Fallacy paper published by the Global Warming Policy Foundation (Crockford 2015).

Time will tell if the Guardian and the CBC are as eager to report the positive change this year.

[Note, this is the same Jon Aars who gave numerous media interviews a couple of weeks ago regarding the phenomenon of a Svalbard polar bear eating a white-beaked dolphin in April 2014 that got hyped around the world. Somehow, the pronounced turn-around in sea ice conditions that was in progress at the time the dolphin eating occurred (Svalbard had average or above-average sea ice from early August onward, Fig. 3 below) did not enter into the story – if Aars mentioned it, the media didn’t report it.]

Figure 3. Sea ice extent at 5 August 2014. Almost everywhere except Svalbard was below average.

Figure 3. Sea ice extent at 5 August 2014. Almost everywhere except Svalbard was below average; Svalbard had more ice than usual. Click to enlarge.

See these related posts, with maps and references:
Barents Sea polar bear condition varies with AMO and spring sea ice conditions March 10, 2014

Barents Sea polar bear status and sea ice declines October 15 2013

Polar bears move around as sea ice habitat changes – this is what resilience looks like April 14, 2014

Barents Sea polar bear cubs – new data for 2014 made to sound ominous June 2, 2014

Footnote 1. From the NSIDC report for October 2014:

Arctic sea ice and the Madden-Julian Oscillation
A new study looks at the impact of a different mode of large-scale atmospheric variability, the Madden-Julian Oscillation, which appears to impact the ice cover on a shorter 30- to 90-day time scale. The Madden-Julian Oscillation is primarily driven by convection in the tropics, but causes changes in atmospheric circulation that impact the high latitudes. The impact on sea ice was found to be stronger during the winter season than in summer. It affected both the Atlantic and Pacific sectors and was confined to the marginal ice zone [which “extends 100 to 200 km from the ice edge into the ice pack, where waves and swells affect the ice”]. The impact on sea ice also varies regionally, often showing opposing effects, such as between the Barents and Greenland seas in winter. [my bold]

References
Crockford, S.J. 2015. The Arctic fallacy: sea ice stability and the polar bear. GWPF Briefing 16, Global Warming Policy Foundation, London. http://polarbearscience.com/2015/06/08/my-new-arctic-fallacy-paper-sea-ice-stability-and-the-polar-bear/  Open access.

Henderson, G. R., B. S. Barrett, and D. M. Lafleur. 2014. Arctic sea ice and the Madden-Julian Oscillation (MJO). Climate Dynamics 43 (7-8): 2185-2196. http://link.springer.com/article/10.1007/s00382-013-2043-y?wt_mc=alerts.TOCjournals Open access.

Abstract
Arctic sea ice responds to atmospheric forcing in primarily a top-down manner, whereby near-surface air circulation and temperature govern motion, formation, melting, and accretion. As a result, concentrations of sea ice vary with phases of many of the major modes of atmospheric variability, including the North Atlantic Oscillation, the Arctic Oscillation, and the El Niño-Southern Oscillation. However, until this present study, variability of sea ice by phase of the leading mode of atmospheric intraseasonal variability, the Madden–Julian Oscillation (MJO), which has been found to modify Arctic circulation and temperature, remained largely unstudied. Anomalies in daily change in sea ice concentration were isolated for all phases of the real-time multivariate MJO index during both summer (May–July) and winter (November–January) months. The three principal findings of the current study were as follows. (1) The MJO projects onto the Arctic atmosphere, as evidenced by statistically significant wavy patterns and consistent anomaly sign changes in composites of surface and mid-tropospheric atmospheric fields. (2) The MJO modulates Arctic sea ice in both summer and winter seasons, with the region of greatest variability shifting with the migration of the ice margin poleward (equatorward) during the summer (winter) period. Active regions of coherent ice concentration variability were identified in the Atlantic sector on days when the MJO was in phases 4 and 7 and the Pacific sector on days when the MJO was in phases 2 and 6, all supported by corresponding anomalies in surface wind and temperature. During July, similar variability in sea ice concentration was found in the North Atlantic sector during MJO phases 2 and 6 and Siberian sector during MJO phases 1 and 5, also supported by corresponding anomalies in surface wind. (3) The MJO modulates Arctic sea ice regionally, often resulting in dipole-shaped patterns of variability between anomaly centers. These results provide an important first look at intraseasonal variability of sea ice in the Arctic.

Polar bear habitat update: many bears on the ice in Hudson Bay, lots of sea ice globally

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Polar bear habitat over Hudson Bay was average this week (at 60% coverage), despite the odd pattern of breakup – but the end of spring in the Arctic is only 5 days away and there is still plenty of polar bear habitat in all regions.

Hudson Bay breakup 2015 June 22 and 24_sm

According to the Canadian Ice Service (CIS), there is still more ice in the eastern portion of the bay than usual and much less in the northwest (Fig. 1 below). There is far more ice than average ice in Hudson Strait, the approach to southern Davis Strait.

Figure 1. Hudson Bay sea ice, difference from average at 22 June 2015. Blue is less than average, red is more than average. CIS.

Figure 1. Hudson Bay sea ice, difference from average at 22 June 2015. Blue is less than average, red is more than average. CIS. Click to enlarge.

Figure 2. Sea ice concentration for Canada at 25 June 2015. End of spring for the Arctic is 30 June. CIS.

Figure 2. Sea ice concentration for Canada at 25 June 2015. End of spring for the Arctic is 30 June. CIS. Click to enlarge.

Andrew Derocher reports (Fig. 3, via twitter) that 7 out of 9 Western Hudson Bay females with collars are still out on the ice (see previous post: Up to 20% of collared polar bears found on ice that officially does not exist, says the PBSG). Notice in his map that at least 3 of those bears appear to be in open water. It’s likely the ice-melt phenomenon I’ve discussed before, that satellites interpret melt-ponds on ice as open water. This suggests, as far as polar bears are concerned, that there is actually more “useable” sea ice out there than the ice maps indicate.

A few bears have come ashore (a few always do before it’s absolutely necessary), but at least one of those captured on camera was in excellent condition (see video here).

See discussion of breakup dates here, here, and here – but it is clear we are well past the point of breakup being “early” (for dates since 1991) for Western Hudson Bay polar bears, and approaching average (1 July).

Figure 3. Locations of nine Western Hudson Bay polar bears on 22 June 2015. Tweet from polar bear biologist Andrew Derocher, 23 June 2015.

Figure 3. Locations of nine Western Hudson Bay polar bears on 22 June 2015. Tweet from polar bear biologist Andrew Derocher, 23 June 2015. Click to enlarge.

In the Beaufort Sea, ice coverage is a bit below average (Fig. 4) but there is still lots of ice left for bears to keep hunting (Figs. 5), with much 40-50% concentration of ice showing.

Figure 4. Sea ice coverage for the Beaufort Sea, week of 25 June, 1968-2015. CIS.

Figure 4. Sea ice coverage for the Beaufort Sea, week of 25 June, 1968-2015. CIS. Click to enlarge.

Figure 6. Sea ice concentration over the Chukchi and Beaufort Seas. NRL, http://www.nrlmry.navy.mil/  courtesy WUWT Beaufort Sea Ice Page.

Figure 6. Sea ice concentration over the Chukchi and Beaufort Seas. NRL, courtesy WUWT Beaufort Sea Ice Page. Click to enlarge.

The same is true for Barents Sea bears (Fig. 7) – somewhat less ice than average but still enough to serve as a hunting platform, according to the Norwegian Ice Service (NIS). And despite what some folks will tell you, apparently that’s good enough – Svalbard bears are doing very well this year, with a good crop of new cubs.

Figure 7. Barents Sea ice concentration at 25 June 2015. NIS.

Figure 7. Barents Sea ice concentration at 25 June 2015. NIS. Click to enlarge.

What about the entire Arctic? A bit less sea ice than average globally (Fig. 8) but still enough over continental shelves for polar bears who will eventually have to spend their summer fast on shore, to continue hunting seals a bit longer.

Figure 8. Global sea ice extend with anomaly for 23 June 2015. NSIDC,  courtesy. WUWT Sea Ice Page.

Figure 8. Global sea ice extend with anomaly for 23 June 2015. NSIDC, courtesy. WUWT Sea Ice Page. Click to enlarge.

Pacific walrus sob stories begin again

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Now we have poor hunting conditions in the Bering Strait touted as evidence that “walrus migration patterns have changed” with the implication that this is because “…the past eight years have had the eight lowest amounts of summer sea ice on record” due to man-made global warming.

Walrus 2012 July USGS

A subsistence lifestyle is hard, particularly so if it depends on a highly mobile, migratory herd animal. Think Barren-ground Inuit caribou hunters, who often starved because herd sizes declined for a few years or moved unpredictably.

Many factors – seasonal weather, last year’s winter conditions, size of the herd, food supply – all affect where and when a migratory herd will move and the likelihood it will be positioned for optimal harvesting by hunters. Add another highly variable factor into that – Bering Sea ice – and you have a highly unpredictable food supply, especially if you sit in one spot (like on St. Lawrence Island) and expect that migratory herd animal to come within reach.

Hunting walrus from St. Lawrence Island depends on just the right combination of ice and winds. Too much ice is not good, too much open water is not good, and too much wind is not good.

Alaska Dispatch, courtesy the Associated Press, reports St. Lawrence natives are again short of walrus meat because of “warm temperatures”: “Warming temps push walrus north, leaving Alaska villages without traditional food source” (Rachel D’Oro, The Associated Press, August 6, 2015). And the caption of the above USGS (A. Sonsthagen) photo predictably implies all current hunting troubles can be blamed on climate channge:

“The walruses in this July 2012 file photo are hauled out in the Eastern Chukchi Sea. Walrus migration patterns have changed as sea ice and other environmental factors have shifted — and that’s spelled trouble for Alaska Native communities who hunt them for subsistence.”

The people of St. Lawrence Island and the Bering Strait that depend on walrus for subsistence have my sympathy, they indeed have a hard life – but this is not a tale of woe about the status of Pacific walrus and changing summer sea ice.

Bering Strait natives hunt walrus in spring, from mid-April to early June (Huntington et al. 2013). All indications are that walrus are moving differently than they used to in summer because the population is now very large.  As far as I know, there is no new population information on walrus that wasn’t available last year, when I covered this topic extensively (Crockford 2014; video below).



Pt Lay map Google marked
From the above news item, which included an interview with Wales (Bering Strait) resident Anna Oxereok:

Her brother caught two animals this spring and shared the meat and fat, but it didn’t go very far in the village of 150. She’s thankful for what she got, though. It’s become increasingly difficult to land a walrus.

Other remote communities at the edge of the Bering Sea also are seeing a steep decline in walrus harvested the past several years. Walrus, described by some as having a taste between veal and beef, is highly prized by Alaska Natives as a subsistence food to store for winter, with the adult male animals averaging 2,700 pounds. The sale of carved ivory from the tusks, legal only for Alaska Natives, also brings in supplemental income to communities with high unemployment rates.

Hunters and scientists say walrus migration patterns are veering from historical hunting grounds as temperatures warm and the ocean ice used by the animals to dive and rest recedes farther north. Village elders also tell biologists the wind is blowing in new directions. In 2013, a late-season icepack clustered around St. Lawrence Island, blocking hunters from the sea.

“I think one of the biggest issues is that things have gotten so variable. It’s hard to really predict what’s going to happen,” said Jim MacCracken, Alaska walrus program supervisor for the U.S. Fish and Wildlife Service.

Iver Campbell and other Yup’ik Eskimo hunters from two St. Lawrence Island communities harvested more than 1,100 walrus in 2003. But a decade later, hunters managed to take only 555 — a fraction of the ideal of one walrus per resident, per year. Things still aren’t looking any better for the 1,430 residents of the villages of Gambell and Savoonga. The recent spring take was 233 walrus, according to preliminary Fish and Wildlife figures.

The shore ice once served to block the wind for hunters but that’s no longer the case, said Campbell, who’s lived all 64 years in Gambell, population 713.

“The ice goes out real fast, melts real fast,” he said. “We don’t have anything to counter the wind and the rough water.”

Science backs that observation. According to the Office of Naval Research, the past eight years have had the eight lowest amounts of summer sea ice on record.

This year, 10 walrus were harvested, according to Diomede hunter Robert Soolook. There’s no shortage of walrus, he said, but they’re migrating sooner. No one has initiated any long-range planning to address the shift, but Soolook believes hunters eventually will need to change their practices, even going out earlier.

“Now that we’ve seen this, we have to start adapting,” he said. [my bold]

Read the rest here.  Something similar was reported last month (8 July 2015).

However, no mention is made in these stories of the low spring ice in 1979, nor of the documented variability of Bering Sea spring ice.

In a study published in 2011, Zachary Brown and colleagues Gert van Dijken and Kevin Arrigo reported that while the Bering Sea was thought to be “rapidly warming and losing sea ice,” the results of their study indicate that “mean annual sea ice extent in the Bering Sea has exhibited no significant change over the satellite record (1979-2009)” and that “the Bering Sea as a whole has undergone no significant change in the timing of ice retreat or advance, or in the length of the ice-free season.”

Brown et al. also said that sea ice cover in the Bering Sea ice is “most aptly characterized by its intense interannual variability.”

Sea ice extent in the Bering Sea varied over their period of study (1979-2009) from a low of 130,000 km2 (in 1979) to a high of 256,000 km2 (in 1999). Ice in 2012 was higher than 1999 by a considerable amount and it was reached in May.

Posts from last year on the walrus issue:

Walrus and sea ice, a summary October 20, 2014

Where have all the walrus gone? October 12, 2014

Mass haulouts of female Pacific walrus as a sign of population health October 7, 2014

High walrus numbers may explain why females and calves are hauling out in droves October 4 2014

References
Brown, Z.W., van Dijken, G.L. and Arrigo, K.R. 2011. A reassessment of primary production and environmental change in the Bering Sea. Journal of Geophysical Research 116:C08014. doi:10.1029/2010JC006766.

Crockford, S.J. 2014. On The Beach: Walrus haulouts are nothing new. GWPF Briefing 11. The Global Warming Policy Foundation, London. Pdf here.

Huntington, H.P., Noongwook, G., Bond, N.A., Benter, B., Snyder, J.A., and Zhang. J. 2013. The influence of wind and ice on spring walrus hunting success on St. Lawrence Island, Alaska. Deep-Sea Research II 94:312-322. Pdf here.

 

Sea ice is not a stable habitat for polar bears – summarized today in The Arctic Journal

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In The Arctic Journal, 7 October 2015: Unstable thinking about polar bear habitat [not my title choice]

Unstable thinking about polar bear habitat_Oct 7 2015 title page

This is a previously unpublished summary, written exclusively for The Arctic Journal, of my peer-reviewed, fully referenced essay on this topic that was published earlier this year by the Global Warming Policy Foundation in their “Briefing Paper” series (#16, June 8, 2015: The Arctic Fallacy: Sea Ice Stability and the Polar Bear), which includes a foreword by Dr. Matthew Cronin, Professor of Animal Genetics at the University of Alaska Fairbanks. Pdf here.

Here are the essential points, one by one:

• Wide variations in spring sea ice habitat are a natural phenomenon and occur independently of any summer sea ice changes that may be due to human-caused global warming.

• Fast ice, where many ringed seals have their pups, can get extremely thick during especially cold winters.

• Strong winds can also drive sea ice onshore, as happens about every 10 years or so off Eastern Alaska and the Northwest Territories of Canada, leaving buckled ice that is too thick in most places for ringed seal breathing holes and birthing lairs, so they move elsewhere; polar bear females emerging from onshore dens with new cubs find no newborn ringed seals to eat, so the tiny cubs die from starvation (as do young bears on their own for the first time).

• Deep snow over sea ice in spring can effectively hide ringed seal birth lairs from hungry polar bears when they need abundant food the most, so many cubs die and adult females may not be able to eat enough to maintain a pregnancy the following year.

• Spring sea ice thickness has been naturally variable over time scales of a few years to decades in the Beaufort Sea, East Greenland, and Hudson Bay; spring snow depth on sea ice is known to vary over short periods – all with devastating effects on local polar bear populations.

• For example, the last time that thick spring ice conditions developed in the Beaufort Sea (2004-2006), biologists estimated the local population dropped 25-50%; similar conditions in 1974-1976 were described as equally devastating.

• Conditions in spring (April- June) are critical because it is the period of on-ice birth, nursing, and mating for ringed seals and is also when polar bears consume two-thirds of their annual prey and seek their mates.

• None of these naturally devastating effects of thick spring ice are included in models that forecast the future for polar bear populations, which model only summer ice changes.

• Biologists now attribute virtually every downturn in population size of polar bears to declines in summer sea ice blamed on human use of fossil fuels: they have shifted the blame for the devastation caused by thick spring ice or heavy snow onto recent summer ice declines, allowing them to claim that summer ice changes are manifestations of unprecedented, human-caused habitat instability.

• The assumption that Arctic sea ice is a naturally stable habitat over short time frames is a biological fallacy: predictive population models based on this myth are flawed, their results illusory because they do not take critical spring sea ice changes into account.

• However, the International Union for the Conservation of Nature (IUCN) and the US government have, for the first time, accepted modeled (future) population declines of Arctic species based on modeled (future) summer sea ice changes as valid threats to their survival, all built upon this fallacy.

Given what we now know about the animals and their naturally changing habitat, it is time to concede that existing data do not support predictions that polar bears are threatened with extinction due to summer habitat instability.

Spring sea ice prediction for next year off Newfoundland: extensive ice coverage

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EATEN – my new polar bear attack novel – is set in Newfoundland 2025 for a reason. I wondered: what if sea ice coverage 10 years from now is as high or higher than it has been for the last two years, with inevitable positive effects on Davis Strait harp seal and polar bear populations?

The Canadian Ice Service prediction for this region, released earlier this week (1 December 2015, see references for link), is that 2016 is set to meet my “what-if” scenario handily. Nine years to go! See the CIS expected ice coverage for 19 February 2016 below (CIS fig. 3):

2016 Newfoundland Ice outlook for 19 Feb 2016_at Dec 1 2015

How does the above ice map compare to the last two years? At least as high or higher. Have a look below.

18 February 2015

Sea ice Canada 2015 Feb 18_CIS

19 February 2014

Sea ice extent Canada_2014 Feb 19_CIS

Fast forward about three weeks to see what ice coverage was like as it neared its peak for the region (the time of year when the action in EATEN takes place), starting with last year (two weeks before a polar bear was sighted swimming near the Hibernia oil drilling platform):

12 March 2015

Sea ice extent Canada 2015 March 12 CIS

12 March 2014

Sea ice extent Canada 2014 March 12_CIS

In conclusion, if CIS proves to be correct in their seasonal outlook then sea ice coverage in eastern Canada in the spring of 2016 will be as great or greater than 2014 and 2015.

Remember that sea ice experts have said (Swart et al. 2015) that the recent lack of overall decline in sea ice coverage for September (2007-2014, now extended to 2015: extreme variation but no statistically significant declining trend, see their fig. 3 below) could last another 10 years or more, even if their modeled prediction for much reduced ice cover by 2100 are correct.

 

Swart et al 2015 sea ice pause Fig 1

In contrast, winter sea ice coverage (March) is not predicted to decline by 2100 (Amstrup et al. 2007:9; Durner et al. 2009:44).

References
Amstrup, S.C., Marcot, B.G. and Douglas,D.C. 2007. Forecasting the rangewide status of polar bears at selected times in the 21st century. Administrative Report, US Geological Survey. Reston, Virginia.

Canadian Ice Service 2015. Seasonal Outlook, Gulf of St Lawrence, East Newfoundland Waters and Labrador Coast, Winter 2015-2016. Environment Canada, CIS, December 1. PDF 2016 Newfoundland St Lawrence outlook_Dec 1 2015

Durner, G.M., Douglas, D.C., Nielson, R.M., Amstrup, S.C., McDonald, T.L. and 12 others. 2009. Predicting 21st-century polar bear habitat distribution from global climate models. Ecological Monographs 79: 25–58.

Swart, N.C., Fyfe, J.C., Hawkins, E., Kay, J.E. and Jahn, A. 2015. Influence of internal variability on Arctic sea-ice trends. Nature Climate Change 5(2): 86–89. [paywalled]


Hungry polar bear attacks: why my novel “Eaten” is set in early March

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As I’ve pointed out previously, polar bears are leanest – and thus, hungriest and potentially the most dangerous to humans – at the end of winter (i.e. March).

Polar bear feeding by season simple_Nov 29 2015

That is why the unexpected prospect of hundreds of lean and hungry polar bears coming ashore in early March hunting available human prey would be a truly terrifying and daunting experience. Such a speculative scenario stands in marked contrast to an actual incident in July that involved a single well-fed bear that attacked a man asleep in a tent because he and his companions had chosen to dismiss the known risk.

Any predatory attack by a polar bear is terrifying but which is potentially the more deadly? One you can reasonably expect (and thus prepare for) or one that comes out of the blue and catches everyone unprepared?

The first scenario is what happens in my novel, Eaten: it is truly a fierce battle between man, beast and Nature, where an unpredictable twist of biological fate takes scores of Newfoundland communities by surprise, leaving them unprepared for a deadly onslaught of hungry, man-eating polar bears. [Buy before December 15 for shipping before Christmas! Details and links below; some discounts available]

EATEN_cover full sm

The second scenario is what happened to a Sierra Club lawyer, depicted in a little book called “Meltdown: Terror at the Top of the World” by Sabrina Shankman. Shankman’s book is a contrived battle between man, beast and Nature and is being promoted with the phrase “ice melts, bears starve” – as if Arctic sea ice did not melt every year at this time and the bear who attacked the lawyer in July was starving.

The bear was not starving – none of the descriptions of the attack suggested it was skinny or starving. It was only described as a big male that was chased away after the attack and not seen again. The attack had nothing to do with unprecedented melting ice or ‘climate change’ (i.e., anthropogenic global warming), yet that is how it is portrayed in Shankman’s little book.

Melt-down_Terror at the Top of the World_Nov 12 2014 press release book cover

“Ice Melts, Bears Starve: Meltdown, Terror at the Top of the World” Below is an excerpt from my review of the book (RANGE Magazine, Spring 2015: A Harrowing Encounter, longer excerpt here).

Harrowing encounter_2015 title

“I have little doubt the man mauled by the bear was indeed terrified and that his companions were as well. However, that horror is exploited shamelessly in this book as a means to promote anxiety over the future survival of polar bears and instill panic over a prophesied Arctic “meltdown.” It uses the gruesome details of a predatory polar bear attack—a known media and publishing draw—as bait to sell a false message that Arctic sea ice is in an unnatural state of decline and polar bears are in peril.

Not only did the attack itself have nothing to do with a starving bear but the population to which the bear belonged has been increasing in size despite sea ice declines. As for the “peril” of polar bear extinction emphasized in the book, models used to predict such a dismal future have been declared unscientific by top conservation experts. [SJC: see recent IUCN Red List update here]

The polar bear is not “losing its natural habitat to a manmade meltdown”– neither is it “battling starvation” or “facing extinction.” Such blatant misinformation distracts from the take-home message that should have been the focus of this book: hikers who travel unprepared in polar bear territory put their lives at risk.” [my bold]

Polar bears are most hungry in March and that is the time when they are most at risk of starvation – and therefore the most dangerous of predators – if there is a shortage of their natural food (newborn Arctic seals).

The terror described in Eaten is not only possible but quite plausible under certain circumstances, which makes it all the more horrifying. You thought JAWS was scary? This is even scarier.

Give this novel a try – it’s available in paperback and ebook formats (Amazon; Barnes & Noble; iTunes, Kobo ebooks; for outlets outside North America, search your local Amazon site or here). I think you’ll find this piece of speculative fiction to be a much more thought-provoking and informative read than the false shock and alarm found in Shankman’s 94 page volume. Makes a great gift for friends and family that would never read a science book.

EATEN_A new novel_final_lg

Polar bear survival: habitat 2013 vs. 2016 for 22 January

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Using sea ice maps issued by the National Sea Ice Data Center (NSIDC), it’s interesting to compare these two years with respect to polar bear health and survival (keeping in mind that no polar bears live in what I like to call the armpits of the Arctic – the Sea of Okhotsk, the Baltic Sea or in the Gulf of St. Lawrence)1:

22 January 2016

Sea ice extent 2016 Jan 22 NSIDC

22 January 2013

Sea ice extent 2013 Jan 22 NSIDC

Ice extent is below average in the Barents Sea this year, as it was at this time in 2013 (especially around the Svalbard Archipelago, see map below) and yet, all the Svalbard polar bears did not die: in fact, a count conducted in August 2015 revealed a 42% increase in Svalbard-area bears since 2004.

22 January 2016 Svalbard:

Svalbard sea ice extent 2016 Jan 22_NIS

22 January 2013 Svalbard:

Svalbard sea ice extent 2013 Jan 22_NIS

Conclusion

At the local level, slightly less extent of sea ice in winter (Jan-March) does not make any appreciable difference to polar bear health and survival, despite what some outspoken polar bear specialists imply. The fact is, the biologists own studies have shown that most polar bears eat few seals during the dark and cold of winter months. That’s why polar bears are at their leanest at the end of winter (see “Polar bears in winter” review here) and why good spring feeding conditions (April-June) are so critical.

Polar bear feeding by season simple_Nov 29 2015

Footnote 1. There are a few historic records of polar bear sightings in the Gulf of St. Lawrence during the cold Little Ice Age time period which I will review in a future post.

Beaufort Sea fractured ice due to strong Beaufort Gyre action – not early melt

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The Canadian Ice Service has a cool NASA animated video showing the Beaufort Gyre in action – you can actually see the solid mass of ice crack and swirl west and north under the pressure of the massive corkscrew current – see original here (tips on getting yourself oriented in the video below the screencap) and view below, for Apri 4- May 3, 2016:

Beaufort Gyre video screencap_21 April 2016_labelled

Note that the video is oriented with Banks Island on the bottom and the shore of Alaska along the left-hand side, as if the locator map provided was rotated as below:

Beaufort Gyre video screencap_locator map_rotated

The big ‘bite” of ice being torn out to the south of Banks Island is the Amundsen Gulf.

The caption for the NASA video says this (my bold):

“MODIS Terra imagery taken between April 4 and May 3, 2016 of the Beaufort Sea. The animation highlights the gradual ice breakup due to the Beaufort gyre.

So, early breakup here is due to Beaufort Gyre action – not early seasonal melt.

A simplified graphic of the Beaufort Gyre in relation to Arctic circulation (from Athropolis):

Beaufort Gyre_Athropolis

Here’s how that open water looks on the Canadian Sea ice map for 11 May 2016:

Sea ice extent Canada 2016 May 11 CIS

Here it is according to the NASA Worldview imagery (for 9 May, due to clear skies; my labels):

Beaufort Gyre_NASA at 9 May 2016_WORLDVIEW

Two maps from the US Naval Research Lab shows how ice thickness has changed between early April (7 April, below) and early May (11 May 2016, follows). The fracturing of the ice is evident in the most recent image and makes it clear it is not only thin ice that is breaking – there is fracturing in 3.5-4.0 m and even 5.0 m thick ice as well as in the thinner (see more maps at the WUWT Sea Ice Page):

Beaufort sea ice thickness_2016 April 6 NRL

Beaufort sea ice thickness_2016 May 11 NRL

As I pointed out in my last post, open water at this time of year is generally good news for polar bears because it’s good news for seals, which I discussed last year in relation to open water in spring:

“…here is what marine mammal biologists Ian Stirling and colleagues had to say about polar bears and the Cape Bathurst polynya in spring (Stirling et al. 1981:49):

Polar bears prey mainly upon ringed seals and, to a lesser degree, on bearded seals. Polar bears appear to be more abundant in polynya areas and along shoreleads, probably because the densities of seals are greater and they are more assessable. For example, between March and June in the Beaufort Sea from 1971 through 1975, 87% of the sightings of polar bears were made adjacent to floe edges or in unstable areas of 9/10 or 10/10 ice cover with intermittent patches of young ice.” [my bold]

Later, they discussed why these areas of open water can be so important in the Southern Beaufort area (Stirling et al. 1981:54):

“One useful approach is to ask what would happen if the polynya was not there? Obviously this is impossible to evaluate on an experimental basis, but by examining the consequences or natural seasonal variation, some useful insights can be gained. For example, the influence of rapidly changing ice conditions on the availability of open water, and consequently on populations of seals and polar bears, has been observed in the western Arctic. Apparently in response to severe ice conditions in the Beaufort Sea during winter 1973-74, and to a lesser degree in winter 1974-75, numbers of ringed and bearded seals dropped by about 50% and productivity by about 90%. Concomitantly, numbers and productivity of polar bears declined markedly because of the reduction in the abundance of their prey species. …If the shoreleads of the western Arctic or Hudson Bay ceased opening during winter and spring, the effect on marine mammals would be devastating.”[my bold]

In other words, Stirling and colleagues suggested in 1981 that the marked declines in ringed seal, bearded seal and polar bear numbers in the mid-1970s (discussed many times on this blog – most recently here) was due primarily to the fact that the Cape Bathurst polynya did not develop as usual because thick ice conditions prevented it.

Polynya references cited above are in that post (Tracking polar bears in the Beaufort Sea in April 2016 and early polyna formation).

It’s possible the kind of open water we’re seeing this spring is good for seals but not so good for polar bears but that remains to be seen. As far as I know, this is a new situation that has not previously been witnessed with this kind of precision – it doesn’t mean it has never happened before, just that we have never been able to watch it happen.

But if it’s bad news for polar bears, it will only serve to emphasize how critical spring conditions are for the bears – if more individuals than usual cannot feed as intensively as they need to, they will have trouble making it through the summer and winter later in the year. However, conditions would have to be exceedingly bad to be more harmful to polar bears than thick spring ice conditions, such as occurred in 1974-76 and 2004-2006, when many, many bears died of starvation.

Beaufort Sea breakup in April 2016 NASA video

More polar bear habitat in Hudson Bay region at mid-May than in 2006 & 2011

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What a difference a bit of historical perspective can make to one’s attitude on the annual Arctic sea ice breakup.

masie_all_r10_v01_2016137_4km

The usual recent pattern (since 1979) has been for breakup to begin on the east side. However, this year and last (below), it has begun in the NW (as it did in 1990 and a few other years).

Not all of the open water is due to melt, of course. As I discussed last week in relation to the Southern Beaufort Sea, winds and prevailing currents at this time of year start to fracture the ice and move it around well before much significant melt has begun.

Compare 2016 (above) to 2006 (below), when there was 0.1 mkm2 less overall – with much less ice in Hudson Strait and in the east of Hudson Bay than this year:
masie_all_r10_v01_2006136_4km

Compare to 2011, when there was also 0.1 mkm2 less overall than this year:
masie_all_r10_v01_2011136_4km

It’s important to keep in mind that the intensive feeding season for polar bears is drawing to a close – within another two weeks, most young-of-the-year seals will be in the water feeding and inaccessible to bears.

The only seals on the ice during June and July are predator-savvy adults and subadults that have hauled out to moult and for these seals the rapidly disintegrating ice creates many escape routes. That means that as long as the ice breakup sequence allows polar bears to get their fill of young seals before the end of May, even during early breakup years most bears should be fat enough to survive the coming summer and winter fasts (see more here). So we should expect to see some bears coming ashore within the next two weeks.

Last year? Rather like this year – certainly the same overall total:

masie_all_r10_v01_2015136_4km

Not all of this newly-opened water is melt, of course. Strong winds and prevailing currents also have an impact, and this year the sea ice is being driven away from the NW coast.

Ice speed drift 2016 NRL May 16

Here’s what the Canadian Ice Service map looks like for 17 May 2016:

Sea ice extent Canada 2016 May 17 CIS

East Coast crawling with polar bears since early March thanks to the pack ice

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The  hot polar bear news right now is the large number of sightings of bears onshore in Newfoundland and Labrador – even the CBC is impressed.

Melrose nfld Polar Bear 02_2017 April 3_Brandon Collins shared photo The Packet

Photo taken by Brandon Collins in Melrose (on the Trinity Bay side of the peninsula) Monday 3 April 2017

All the bears have been brought to land by the abundant pack ice that’s been present off Labrador and northern Newfoundland (the territory of Davis Strait polar bears), which also killed a humpback whale that got trapped against the north shore (a not unusual event, apparently).

Mapping the reports of polar bear sightings since early March helped me get a handle on the total number of encounters: more than a dozen, it turns out.  There have been a few bear sightings in this region every year recently but such high numbers are remarkable, especially so early in the season. When will it end?

Increased numbers of bears in the population is one explanation for increased numbers of encounters onshore at this time of year, although recent storms may have encouraged more bears than usual to come ashore in Newfoundland.

My picture annotated map and a list of sighting reports, with links, is below but stay tuned: this story may not be over yet.

UPDATE 4 April: more photos and sea ice maps added below.

UPDATE 5 April: another sighting, in St. Brendan’s (west of Bonavista), added to the map below and quotes from one witness. The map is now Version 2. A sea ice map for 5 April has also been added at the end of the post.

UPDATE 9 April: another sighting and a bear casualty, see below. Map revised again.

UPDATE 14 April: CBC Newfoundland article (12 April: Highway of ice: Easy route for polar bears chasing food, prof says) based on my radio interview that aired 11 April.

UPDATE 22 April: Another sighting west of St. Anthony on Wednesday, 19 April has been added to the map (now Version 4) and an alert that I’ve added a new post (21 April) about the claim by one vocal polar bear specialist that all of these sightings are the result of “failed” sea ice conditions off Newfoundland and Labrador this year (seriously, I’m not making this up). I’ve added the most recent ice map at the end of this post.

Here’s a map of the sightings (photos acknowledged below), now Version 4 (updated 22 April ):

East Coast March April polar bear sightings 2017 V4_22 April_PolarBearScience

List of sightings, by date and location

All the encounters of bears that generated photos show well fed bears in good condition.

St. Anthony area, in Great Brehat (early March 2017, reported 1 April) “Driver narrowly misses polar bear on commute to St. Anthony”

Footprint photos was all Amy Randell got of the polar bear that ran in front of her car, with 6 year old son Cruz for scale:

Great Brehat footprints_Early March 2017 cruz-randell_Amy Randell submitted to CBC

Twillingate, Newfoundland (9 March 2017) “Polar bear drifts past Twillingate” (last sighting was in March 2000)  [no photo]

Black Tickle, Labrador (7 March 2017) “7 polar bears visit stormbound Black Tickle”

Sherman Downey shared this photo he took in Black Tickle:

Black Tickle polar-bear 7 March 2017_Sherman Downey shared photo

Mary’s Harbour, Red Bay and Black Tickle (15 March 2017) “Polar bears spotted near three coastal Labrador communities”

Photo from one of those communities submitted to The Telegraph below (I’ve put it in Red Bay on the map):

Labrador polar-bear-2070615_submitted photo 15 March 2017 Telegraph

Wesleyville, Newfoundland (29 March 2017) “Photographer captures ‘praying’ polar bear in front of cross in Newfoundland” (See more of the copyrighted photos here).

Wesleyville nfld praying bear_THE STAR 30 March 2017 headline

The “praying bear” appears to be the same animal as photographed by Dana Blackmore, below (shared with the CBC):

polar-bear-new-wes-valley_Dana Blackmore shared_CBC 3 April 2017

Bonavista, Newfoundland (2-3 April 2017) “There could be more than one polar bear on Bonavista Peninsula”  (older story here).

Photo below by Brandon Collins at Birchy Cove near Bonavista on Sunday 2 April of a female and cub (an older one, not a young of the year), shared with the CBC:

Bonavista nfld Polar Bear 2017 April 2_Brandon Collins shared photo CBC

Photo below by Brandon Collins in Melrose (on the Trinity Bay side of the peninsula) of a large lone male spotted Monday 3 April, shared with The Packet:

Melrose nfld Polar Bear 01_2017 April 3_Brandon Collins shared photo The Packet

ADDED 4 April: More photos of the Melrose bear from this morning of a bear who is really poking around close to houses and sheds and causing trouble.

Submitted to the CBC, “Polar bear plans getaway after warning issued in Bonavista area” taken 4 April and submitted by Shelly Ryan – see the link for more photos – pulling apart a snowmobile seat and investigating a shed:

Melrose nfld Polar Bear 01 snowmobile_2017 April 3_Shelly Ryan shared photo CBC

Melrose nfld Polar Bear 02_2017 April 3_Shelly Ryan shared photo CBC

Same bear, different photographer (there is also a video at the link), taken 4 April by Dion Diamond at Melrose (sounds like the same area as the CBC incident), reported in The Packet “Polar bear steals snowmobile seat in Melrose”:

Melrose nfld Polar Bear 02_2017 April 4_Dion Diamond shared photo THE PACKET

St. Brendan’s, an offshore island between Wesleyville and Bonavista (5 April 2017) “Polar bear spotted near St. Brendan’s” Another report (via VOCM, has more photos shared by resident Tracey Hynes, including the one below):

“After exploring St. Brendan’s, Hynes said the bear headed back to the ice, where he killed and ate a seal, cleaned himself up, and ventured back to explore the community. He was startled, however, and rushed back to the ice and disappeared from sight.” [The Packet, 5 April 2017]

St brendan's bear 01 VOCM report 5 April 2017 Tracy Hynes

However, just after 5 pm local time, the St. Brendan’s bear was tranquilized, captured and airlifted out of the community (5 April 2017), after getting a little too close for comfort.

St brendan's bear airlifted out 5 April 2017 VOCM 5 PM

Another view of the airlift operation in St. Brendan’s:

Stbrendansbear2 airlift

Resident Vernon Buckle reported on 4 April via Twitter that he’d seen polar bear footprints a few days earlier on the Labrador coast south of Red Bay:

“Followed fresh tracks inland on Saturday, north of Pinware. An adult/2 young were seen earlier in day swimming near Capstan Island.”

Footprints from Pinware sighting:

Pinware footprint_Vernon Buckle

Pinware and Capstan Island locations on the south shore of Labrador:

Pinware and Capstan Island location Labrador

Little Catalina, just southeast of Bonavista (8 April 2017), with an unhappy ending: “Conservation officers tracking polar bear in Little Catalina”  and “Department of Fisheries and Land Resources explains situation that led to killing of polar bear” follow-up.

A polar bear spent the day on the ice flows just off the community but decided to come ashore for a look around town. That made local conservation officers nervous, especially with all the people crowding around for a look and a snapshot. Unfortunately, the bear ended up dead by the end of the day, shot by conservation officers, which caused some hard feelings.

Photos below by Brandon Collins:

Little Catalina pb 8 on the rocks April 2017 Brandon Collins_The Pilot

Little Catalina pb 8 April 2017 Brandon Collins_The Pilot

Brookside, on the Burin Peninsula, southern Newfoundland (9 April 2017): “Brookside Gets Surprise Visit from Polar Bear

It’s unusual for a polar bear to get this far south but pans of ice and mini-icebergs that don’t show up on ice maps can swirl around quite a bit, especially with the storms that Newfoundland has had over the last couple of weeks. Brookside is on the south shore of Newfoundland, west of St. John’s.

Brookside southern Nfld location

“The Department of Fisheries and Land Resources is advising the public there are reports a polar bear was seen Sunday on the Burin Peninsula near the communities of Brookside, Parker’s Cove and Boat Harbour.

Roslyn Denty managed to snap several photos of the animal in Brookside and posted them to her Facebook page.

“A lot of pack ice outside and he came in on the ice,” she commented.”

This photo by Roslyn Denty is the clearest and shows the bear’s fat little rump; there are other shots at the link. While it seemed unlikely that this bear’s adventure would end well, conservation officers apparently managed to safely capture the bear and plan to relocate it to the north on Monday (10 April).

Brookside southern Nfld pb_Rosyln Denty_9 April 2017

Parker’s Brook, on Pistolet Bay west of St. Anthony at the tip of the Great Northern Peninsula, northern Newfoundland (21 April 2017): “Public Advisory: Polar Bear Warning Issued for St. Anthony”

No picture is available of the bear but the approximate location is shown below (see marker for “Wildberry Country Lodge” in Parker’s Brook). You can see by the latest ice maps added below and the end of this post that the region is still choked with ice:

Parkers Brook location on Pistolet Bay

According to the latest report,  ice conditions in the Strait of Belle Isle (other side of the Northern Peninsula, facing the Labrador coast) are anything but usual  (19 April 2017, in The Western Star)(my bold):

“According to the Canadian Coast Guard, the ice pack is currently four feet thick or more in places. Combined with chunks of older, harder ice and unseasonably cold temperatures, the ice has cemented together to form a formidable navigational obstacle.

The pressure on the shoreline is so great that the Terry Fox, Canada’s second biggest icebreaker, cannot get through it.

The ferry MV Apollo, which is the link between southern Labrador and the Northern Peninsula on the Newfoundland side of the Strait of Belle Isle, is docked in Blanc Sablon and not going anywhere for the foreseeable future until the ice eases up.

“There was a bit of a southwesterly blow today, but it was not enough wind to move the ice and the pressure there is going to remain,” Rebecca Acton-Bond, the Canadian Coast Guard’s acting superintendent of ice operations in Atlantic Canada, said Wednesday.

“It’s like a wall of solid ice. The captains I have spoken with say they have never seen anything like these conditions in this area ever.”

Ice concentration chart for 19 April 2017 (Canadian Ice Service), St. Anthony is marked:

Newfoundland East daily ice conc 19 April 2017_CIS

Sea ice maps for 2 April through 9 April below (don’t forget that polar bears are strong swimmers), with April 19 (the day of the latest sighting) and April 22 (the date of the latest update) added:

Sea ice extent Canada 2017 April 2 CIS

Sea ice Canada 2017 April 3 CIS

Sea ice Canada 2017 April 4 CIS

Sea ice Canada 2017 April 5 CIS

Sea ice Canada 2017 April 7 CIS

Sea ice Canada 2017 April 8 CIS

Sea ice Canada 2017 April 9 CIS

Sea ice extent Canada 2017 April 19 CIS

Sea ice extent Canada 2017 April 22 CIS

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