Tag Archives: polar bear habitat

Polar bear habitat update: regional differences, melting vs. freezing

The freeze is on: from an annual low of ~5.1 m sq km at 15 September 2014, the sea ice that provides a hunting platform for polar bears is rapidly reforming.

Note that polar bear habitat world-wide is pretty well defined by the extent of sea ice in spring, with three notable exceptions. There are no polar bears (or fossil evidence of polar bears), in the Sea of Okhotsk, the Gulf of St. Lawrence, or the Baltic Sea.

Bears in some areas spend time on land in late summer/early fall but the amount of time varies widely.

Polar bear distribution and ice extent_PolarBearScience
Have a look at the maps below: the difference in regional coverage between the sea ice at 4 August and 16 October (73 days apart, both covering 7.3 mkm2) might surprise you.
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Tracking polar bears in the Beaufort Sea – August 2014 map

Here is the August 2014 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.”

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 August 2014 is copied below (Fig. 1).

Compare this to July’s map (Fig. 4). The 20 bears from May (down to 13 in June) are now down to 11. All seven of the bears outfitted with glue-on satellite transmitters in April [either males or subadult animals] have either moved out of the area or their tags have fallen off or stopped transmitting. This means that all of the bears shown on the maps below are females.

At the end of August, nearing the minimum extent of ice for this year, seven bears were on the ice and only four were on land.
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Foxe Basin and Hudson Bay have more than average polar bear hunting habitat

This is shaping up to be a banner year for polar bears in Foxe Basin (central Canada), with more ice in this region than there’s been since 1992. Hudson Bay still has a large patch of thick first year ice, more than there has been at this date since 2009, which was a late breakup year.

Hudson Bay Foxe Basin ice map Aug 7 2014 labeled_sm

Ice maps and charts below tell the story.
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Sea ice experts make astonishing admissions to polar bear specialists

Climate scientists specializing in future sea ice predictions made some remarkable statements to polar bear scientists at their last meeting – admissions that may really surprise you.

USFWS_PolarBearNews2013_pg5 labeled

Back on June 26 (reported here), the IUCN Polar Bear Specialist Group (PBSG) posted a summary of its last meeting. So, I was very surprised to find (while there looking for something else), that on 18 July 2014 they had added minutes from the meeting to that summary.

These minutes are a bonanza because among the juicy nuggets of information is a summary of what the three invited climate scientists from Colorado (Jennifer Kay, Mark Serreze, and Marika Holland) had to say and what questions were asked. While real transparency would have involved posting copies of the sea ice presentations and transcripts of the question and answer sessions, this is certainly better than nothing.
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Polar bear habitat: Spring 2014 in Eastern Canada was much better than 1969

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.
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Spring/summer sea ice bonanza for polar bears – conditions excellent again for 2014

Again this year – contrary to predictions – there has been no early breakup of the sea ice on Hudson Bay and even though it’s the height of summer, there is plenty of ice throughout the Arctic to act as a feeding platform for polar bears. This makes it unlikely there will be a longer-than-average summer fast for polar bears again this year.

Figure 1. NSIDC MASIE map for June 21, 2014.

Figure 1. NSIDC MASIE map for June 21, 2014.

Sea ice maps around the Arctic for June 21 (and June 24, for Hudson Bay) reviewed and discussed below in relation to polar bear habitat — have a look.

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Davis Strait polar bear habitat higher now than in 1979 and early 1980s

The Davis Strait polar bear subpopulation is said to be ‘vulnerable’ to the supposed effects of global warming because, like Hudson Bay, Davis Strait sea ice retreats every summer, leaving polar bears on land for several months.

However, Davis Strait bears have been upgraded to ‘stable’ status, according to the latest table (2013) issued by the IUCN Polar Bear Specialist Group (see their boundary map for Davis Strait bears below). Recent development of sea ice in the region can only improve that rating.

[More background here and heremap-DavisStrait

It seems that sea ice in Davis Strait is well above normal for this time of year – a recent announcement by the Canadian Ice Service (CIS) says it’s 10% above average, higher than it’s been in 25 years (h/t S. Goddard).

The Canadian Ice Service, an arm of Environment Canada, said there is 10 per cent more ice this year compared to the 30-year average.

We probably haven’t seen a winter this bad as far as ice for the past 25 years,” said Voight, referring to both the amount and thickness of the ice.

He said the Gulf of St. Lawrence is covered and some areas are “quite severe.” [my bold]

Full story here.

Latest ice map (March 12) below from the US National Snow and Ice Data Service (NSIDC).

As I pointed out recently here, Barents Sea ice is below average this year, largely due to natural variation in the Atlantic Multidecal Oscillation (AMO), but is higher over the western Atlantic (Sea of Okhotsk ice is below average too but there are no polar bears there).

There is lots of ice around Labrador and Newfoundland, however.

Sea ice extent 2014 March 12 NSIDC

I thought I let you see exactly what CIS are talking about: what did the ice look like 25 years ago, in 1989? What about 35 years ago, in 1979, the start of the satellite record for sea ice? It might surprise you. Continue reading

Chukchi-Beaufort sea ice atlas: check out polar bear habitat 1850-2013

It’s here – as promised and right on schedule — the sea ice atlas put together by University of Alaska Fairbanks (UAF) now has ice concentration maps for Alaska going back to 1850 — and for every year up to 2013. 

Several examples are included below: August 1850 vs August 1870, and April 1850 vs. April 1920 and April 2012.

For background, see my post announcing the site preview, which was then limited to 1953-2012 data, when it became available in late January.

Sea ice atlas_1850_Aug
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Polar bear habitat update, December – still like 2009

From the end of October to mid-December, there has been a rapid expansion of polar bear habitat.

This month, I’ve constructed two all-in-one images that show the progressive growth of the ice relative to some critical polar bear onshore summer refuge areas and denning territory. I’ve also included a map that compares 2013 to 2009 at 18 December with the average for the 1980s, and one that shows ice thickness.
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Polar bear habitat update, end of November 2013

Freeze-up in the Arctic (~October-November) is important to polar bears because for those animals that have spent the ice-free period on shore (not all do), it marks the end of their summer fast — they can finally resume seal hunting.

Polar bears in the most southern regions, like Southern Hudson Bay, Western Hudson Bay, and Davis Strait (see Fig. 1), routinely experience the longest ice-free period. As these bears all spend the summer on shore, they appreciate a timely return of the ice.

 Figure 1. Polar bear subpopulations defined by the IUCN Polar Bear Specialist Group (PBSG), with a few extra labels added. I’ve rotated the original map 90 degrees (right) to make it easier to relate to the ice maps below. WH is Western Hudson Bay. Courtesy PBSG.  Click to enlarge.


Figure 1. Polar bear subpopulations defined by the IUCN Polar Bear Specialist Group (PBSG), with a few extra labels added. I’ve rotated the original map 90 degrees (right) to make it easier to relate to the ice maps below. WH is Western Hudson Bay; SB is Southern Beaufort. Courtesy PBSG. Click to enlarge.

Southern Hudson Bay bear populations routinely experience an ice-free season that is just as long as it is for Western Hudson Bay bears. However, Southern Hudson Bay polar bears numbers have remained stable over the last 30 years. Some folks insist that Western Hudson Bay bear numbers are shrinking to a worrisome degree, despite indications that the recent decline could be nothing more than a return to sustainable levels after a rapid population increase in the late 20th century (similar to changes documented for the Davis Strait and Barents Sea subpopulations).

Have a look at how sea ice – essential polar bear hunting habitat – has developed within these regions over the last 10 days or so (end of November 2013) and how November 2013 compares to November 1979. The ice maps tell the freeze-up story.
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