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

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.

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