Hudson Bay in early July this year is a mosaic of more-than-average and less-than-average sea ice coverage but apparently, only the less-than-average ice areas constitute the “early breakup” caused by climate change, and only “deniers” would say otherwise.
I say some folks are cherry picking the ice conditions that support a story line they prefer, forgetting that polar bears know better than they do when to come in off the ice.
Continue readingComments Off on Natural flexibility explains W Hudson Bay polar bear movements at breakup better than climate change
Posted in Evolution, Life History, Sea ice habitat
Tagged breakup, climate change, Derocher, evolution, ice charts, melt ponds, polar bear, sea ice, western hudson bay
Contrary to all expert expectations, five female polar bears (45%) out of eleven that had tracking collars attached last year were still out on the sea ice that’s lingering along the western shore of Hudson Bay as of 7 August. And if five collared bears are out there, then there are almost certainly many more without collars doing the same thing. This pattern of bears staying out on the ice long after the so-called ‘critical threshold’ of 50% concentration has passed has been going on since at least 2015 and many bears on tracking maps in July and August appear to be on ice that doesn’t exist.
There are two explanations for this pattern and both are likely true: 1) much more ice actually exists on Hudson Bay than satellites can detect and 2) polar bear experts are wrong that Western Hudson Bay polar bears head to land soon after sea ice concentration drops below 50%. Models that predict a catastrophic future for Western Hudson Bay polar bears (Castro de la Guardia et al. 2013; Molnar et al. 2020) assume that ice coverage of less than 50% in summer greatly reduces polar bear survival. However, if polar bears do not always head to land when sea ice drops below 50% then the models cannot possibly describe their future accurately. In other words, depending on the discredited ‘worst case’ RCP8.5 climate scenario for the most recent polar bear survival model that extrapolates from Western Hudson Bay bear data to many other subpopulations, as I discussed previously, may not be its only fault.
Comments Off on Many W Hudson Bay polar bears still offshore at 7 August despite apparent low ice levels
Posted in Conservation Status, Life History, Sea ice habitat
Tagged assumptions, behavioural plasticity, breakup, contradictions, extinction, Hudson Bay, melt ponds, polar bear, predictions, RCP8.5, sea ice, western hudson bay
Walt Meier, sea ice scientist at NASA Goddard, made a statement yesterday about this year’s ice conditions [2016 Climate Trends Continue to Break Records: July 19, 2016]:
“It has been a record year so far for global temperatures, but the record high temperatures in the Arctic over the past six months have been even more extreme,” Meier said. “This warmth as well as unusual weather patterns have led to the record low sea ice extents so far this year.“ [my bold]
Well, except for Davis Strait/Labrador Sea this spring. And Western Hudson Bay/Foxe Basin this month – plus the fact that late July sea ice in the Laptev Sea is higher than it’s been for more than a decade (more on that below).
I guess totals matter for some things – just not for polar bears. However, it’s nice to see the issue of melt ponds get some attention, since they are such a prominent feature of polar bear habitat during the summer melt season.
Comments Off on Arctic melt ponds get media spotlight as Laptev Sea ice hits an 11 year high
Posted in Life History, Sea ice habitat
Tagged accuracy, Beaufort, Chukchi, extent, ICEBRIDGE, Laptev Sea, melt ponds, NASA, Northeast Passage, satellite radio collars, sea ice, summer
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.
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Comments Off on Alarm over future summer polar bear habitat disguises how good conditions are right now
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
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.
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. Click to enlarge.
Comments Off on Polar bear habitat update: many bears on the ice in Hudson Bay, lots of sea ice globally
Posted in Life History, Sea ice habitat
Tagged Arctic, Barents Sea, Beaufort Sea, breakup, global, habitat, Hudson Bay, melt ponds, polar bear, satellite collars, science, sea ice, spring, summer fast, Svalbard, western hudson bay
USGS biologists were clearly busy this spring putting more satellite radio collars and glue-on tags on Southern Beaufort Sea polar bears but there’s some surprising information in their April 2015 tracking map about current sea ice conditions.
From the 2013-2014 issue of “Polar Bear News” (USFWS).
What’s interesting is that the sea ice maps they use show less dark spots that might be open water this year than were present last year in late April. Oddly, this phenomenon has one prominent biologist worried about “challenging” polar bear habitat developing this year – without mentioning last year at all.
The USGS track map for April 2015 is copied below.1
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Comments Off on Tracking polar bears in the Southern Beaufort, with a sea ice surprise – April 2015 map
Posted in Life History, Sea ice habitat
Tagged Beaufort Sea, Chukchi Sea, Eastern Beaufort, habitat, ice maps, melt ponds, polar bear movements, polar bears, satellite collars, satellite images, sea ice, Southern Beaufort, tracking polar bears, USGS
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