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.
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.
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.
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.
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.
Posted in Life History, Sea ice habitat
Tagged Chukchi Sea, Derocher, habitat, Hudson Bay, melt ponds, polar bear, polar bear science, sea ice, Southern Beaufort, spring ice conditions, summer sea ice, Svalbard, thick spring ice, tracking polar bears, walking hibernation
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.
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.
Posted in Life History, Sea ice habitat
Tagged Barents Sea, Beaufort Sea, Canadian Ice Service, Davis Strait, harp seal, hunting, Labrador, Newfoundland, NSIDC, polar bear, preferred habitat, sea ice, sea ice concentration, spring ice conditions
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.
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.
Posted in Sea ice habitat
Tagged average breakup date, breakup, Canadian Ice Service, concentration, eastern Hudson Bay, habitat, Hudson Bay, Mt. Pinatubo, sea ice, spring ice conditions, western hudson bay
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.
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.
Posted in Life History, Sea ice habitat
Tagged AMO, Barents Sea, Churchill, cubs of the year, Davis Strait, Norwegian Ice Service, polar bear, sea ice, spring ice conditions, spring ice maximum, Svalbard, western hudson bay
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?
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
Posted in Advocacy, Population, Sea ice habitat
Tagged abundance, aerial survey, Amstrup, Beaufort Sea, Bromaghin, Mark Serreze, mark-recapture, polar bear, population estimate, population recovery, Red list, Rode, sea ice, Southern Beaufort, spring ice conditions, summer ice minimum, USFWS
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).
[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.
Posted in Sea ice habitat
Tagged blog stats, Canadian Arctic, Canadian Ice Service, Davis Strait, Gulf of St. Lawrence, Labrador, Newfoundland, pack ice, polar bear habitat, sea ice, sea ice declines, sea ice maximum, southern-most polar bears, spring, spring ice conditions, spring ice maximum
Oddly, it seems some people expect polar bears to sit around and suffer (or die) when local conditions deteriorate, rather than move elsewhere.
While there are perhaps a few places where moving is not really an option over the short term, over the long term (more than one season) polar bears are free to shift to another locale if ice conditions change (either too much ice or too little).
An announcement by the WWF last week (10 April) caught my eye, as it talked about bears moving from one area to another because of changing ice conditions — as if this was surprising, extraordinary and newsworthy. That said, at least they weren’t suggesting the bears are all going to die because of declining ice, which is a huge improvement.
See what you think of this part of the press release (below), in the context of what we know about the movement of bears between regions:
Posted in Conservation Status, Life History, Sea ice habitat
Tagged adaptation, AMO, Amstrup, Barents Sea, dens, Franz Josef Land, Kara Sea, Mauritzen, polar bear, polar bear resilience, pregnant females, satellite radio collars, spring ice conditions, Svalbard, WWF
Following up on my last post (Ian Stirling’s latest howler: “the polar bear who died of climate change”), I tracked down some details contained in the original Norwegian news report but which were left out of the articles that spread the story around the world. I also found some pertinent research posted online that appears to be the work of the researchers who captured this bear in April.
Figure 1. The Norwegian newspaper, The Local (Aug. 7, 2013), says the bear was found on “a small island near Texas Bar” (marked by the square on the above map) in the very north of Spitsbergen, and states it was found on July 7 – details other reports did not bother to include. [“Texas Bar” is a hut built by a Norwegian hunter in 1927]. To have been 250km south of that position in April (when he was tagged), he must have left the ice near the southern tip of Spitsbergen when there was still lots of ice further north.
Posted in Advocacy, Life History, Sea ice habitat
Tagged Ashley Cooper, body condition, climate change, Environmental Monitoring of Svalbard and Jan Mayen, Jon Aars, Magnus Andersen, male polar bears, norwegian news, pertinent research, Spitsbergen, spring ice conditions, starvation, Stirling, Svalbard, Texas Bar, victim of climate change