Tag Archives: spring ice conditions

2016 record low maximum will make headlines but unlikely to affect polar bears

Never mind that the sea ice maximum this year came almost a month later than last year (and close to latest since 1979) – and was lower by only .02 – the US National Sea Ice Data Center (NSIDC) today trumpeted a new record low.  What this means to polar bears, if anything, remains to be seen.

Sea ice extent 2016 March 24 NSIDC_max 14_52mkm2 sm

2015: maximum set February 25 (day 56), at 14.54 mkm2

2016: maximum set March 24 (day 84), at 14.52 mkm2

[The difference in area? Smaller than the Islands of the Bahamas]

Latest maximum extent (since 1979) occurred in 2010 on April 2 (Day 92).

The average date for maximum extent is March 12.

I note, however, that given the lateness of the winter sea ice surge meant that the amount of ice present at 24 March 2016 (see NSIDC Interactive) was more than was present on the same date in 2006, 2007 and 2015.

Clearly, there was plenty enough sea ice in the spring of those years for most polar bears to hunt seals successfully and put on the weight they needed to survive the summer fast ahead. I see no reason to expect 2016 to be different.

Polar_Bear_male_Regehr photo_March 21 2010_labeled
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Worrywart biologists fuel media fearmongering over winter sea ice levels

Have you heard the old adage, “Don’t buy trouble”? I’m thinking we could use a lot more of that attitude from polar bear and Arctic seal biologists these days.

Gulf St Lawrence ice conc 7 March 2016_CIS

In an interview with CBC News yesterday, Department of Fisheries and Oceans Canada (DFO) seal specialist Mike Hammill fed the fear the media wanted to hear while admitting this year’s low ice levels in the Gulf of St. Lawrence will not affect harp seal numbers significantly (7 March 2016, Lack of ice means fewer seal pups off the Magdalen Islands this year: Researcher says impact on overall herd limited, but ice patterns over time could be concern”).

Harp sea newborn_wikipedia

And University of Alberta’s Andrew Derocher has been busy tweeting his heart out that slightly lower than average sea ice levels this winter could mean a “challenging” spring for some polar bears – as if spring isn’t always challenging for some bears (especially young bears that are inexperienced hunters and low in the social hierarchy – meaning bigger, older bears often steal their kills – and old bears that are running out of steam).
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Alarm over future summer polar bear habitat disguises how good conditions are right now

Despite the public outcry last week over future polar bear survival, the polar-bears-are-doomed crowd can’t hide the fact that this year, spring sea ice habitat for polar bears worldwide has been excellent.

A polar bear walks on the Arctic Ocean ice Aug. 21, 2009.

This year on 19 July, for example, Hudson Bay had greater than 150,000 square km more sea ice than there was in 2009 on that date (526.2 vs. 368.5 mkm2)(1992 was a particularly cold year and most bears left the ice as late in 2009 as they did in 1992).1 Conditions have also been excellent for pregnant females around Svalbard – Norwegian polar bear researchers recently reported a good crop of cubs this spring.

Hudson Bay breakup July 20 2015_CIS

Worldwide, there was exactly the same amount of Arctic sea ice present on 18 July 2015 as there was back in 2006 (Day 199) – 8.4 mkm2. By 19 July (day 200), 2015 had more ice than 2006 (8.4 mkm2 vs. 8.3).

All this means that recent summer ice melt has not impinged on the spring feeding period that is so critically important for polar bears. So much ice left in early summer means there was lots of sea ice in the spring (April-June), even in the Southern Beaufort Sea.

The only region with sea ice coverage well below the last five years is the Chukchi Sea (see plots below, click to enlarge). So why aren’t we hearing the-sky-is-falling stories about Chukchi bears? Because biologist have already demonstrated that polar bears in the Chukchi do very well even with no summer sea ice.
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Polar bear habitat update – sea ice for hunting plentiful in all subpopulation regions

Preferred polar bear habitat is said to be 50% concentration or higher over continental shelves, which describes all but the fringes of sea ice extent today, including Hudson Bay, the Southern Beaufort, and the Barents Sea.

Preferred polar bear habitat 50pc concentration_May 8 2015_PolarBearScience

However, polar bears – excellent swimmers that they are – are quite capable of utilizing areas with 15-50% sea ice concentration if necessary (Durner et al. 2004; Rode et al. 2014:79), especially when prey are plentiful.  This would account for the fact that there are still sightings of polar bears in and around northern Newfoundland (see previous post here and photo below1), where ice concentration is in the 30-50% range.

Photo with this news story (7 May 2015): "(Update) Polar bear sighting in Croque"

Photo with this news story (7 May 2015): “(Update) Polar bear sighting in Croque”

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Polar bear habitat update: highly concentrated ice in eastern Hudson Bay this spring

Sea ice in eastern Hudson Bay (bright white in the map below) is more concentrated than at this time last year and similar to the ice found in the Central Canadian Arctic.

Sea ice extent Canada 2015 April 11 CIS

There is more concentrated ice (10/10 concentration) in the east side of the Bay than there was in 1992, a heavy ice year blamed in part on the eruption of Mt. Pinatubo (Chambellant et al. 2012) that resulted in the latest breakup date for Western Hudson Bay since 1991.

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Polar bear habitat update – more spring sea ice around Svalbard than 2014 & 2012

Polar bear habitat for the last week of March is well above average in eastern Canada for the second year in a row. The very low extent of ice in the Sea of Okhotsk – which has contributed strongly to the low maximum extent this year – is irrelevant to our discussion, since no polar bears live there.

Polar_Bear_male_Regehr photo_March 21 2010_labeled

There is a bit more concentrated ice around Svalbard than last year (or in 2012), although ice in the Barents Sea in general is still below average due to the state of the Atlantic Multidecadal Oscillation (AMO). The state of the AMO and its effects on Barents Sea polar bear sea ice habitat has nothing to do with global warming: it’s a cycle that has been documented for centuries (Miles et al. 2014).

Still, there is plenty enough sea ice for polar bear hunting: this is the beginning of the critical feeding time for all polar bears (see here and here), but especially for the survival of new cubs-of-the-year, so I have a few words about Western Hudson Bay cubs below.

Have a look for yourself.
Update: Added 20 March 2015, comparison maps from Cryosphere Today for 2006 vs. 2015.
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If summer ice was critical for S. Beaufort polar bears, 2012 would have decimated them

Did we hear a huge hue and cry in 2013 about starving polar bears and low cub survival in the Southern Beaufort Sea? No, we did not. Despite the record-breaking low summer sea ice extent the year before (2012), and despite the fact that USGS biologists were putting collars on polar bear females there the spring of 2013 (Rode et al. 2014), we heard not a peep about a polar bear catastrophe in the Southern Beaufort. Odd, isn’t it?

Sea ice extent 2012 Southern Beaufort_PolarBearScience

Several polar bear biologists and sea ice experts were busy late last fall suggesting to the media that a decline in polar bear numbers in the Southern Beaufort was due to declines in summer sea ice, which they blamed on global warming (see quotes below and earlier discussions here, here and here). However, they made no mention of the fact that the record-breaking September ice extent in 2012 did not seem to have any noticeable effect on polar bear health or survival in 2013.

Sea ice maps from the National Snow and Ice Data Center (NSIDC) tell most of the story about what the media were, and were not, told about summer sea ice in the Southern Beaufort between 2001 and 2013.  Continue reading