Tag Archives: melting ice

Polar bears of W Hudson Bay utilizing a substantial patch of thick first year ice

There’s been no word as yet, either from tour operators or polar bear researchers, that Western Hudson Bay polar bears have come ashore for the summer/fall season. Andrew Derocher reported at the end of June that the bears tagged by his team were still on the ice and as I write this, has not yet reported them ashore.

That pattern is consistent with the presence of thick ice along the west coast of the Bay — from well north of Churchill to the south of Wapusk National Park — for the last few weeks. The weekly chart for 3 July 2017 below from the Canadian Ice Service shows that virtually all of the ice remaining is thick first year ice (>1.2m, dark green on this map):

Hudson Bay weekly ice stage of development 2017 July 3

By the 9 July, the extent of this patch of ice was somewhat reduced but still a very prominent feature over the Bay, suggesting that if adult seals are using this ice as a refuge while molting, some bears may still be attempting to hunt even though their success rate may not be very high:

Sea ice Canada 2017 July 9

Bottom line: As has been the pattern for more than a decade, 2017 will not go down in history as an especially early year for WHB polar bears coming off the ice for the summer/fall season but instead may be as late as last year, when lots of bears were reported off the ice by mid-July at Seal River (just north of Churchill), all in excellent condition.

It remains to be seen if the condition of bears will be as good this year as they were in 2016, given the late start to the season. But it does mean that the lack of trend in breakup dates since 2001 continues: breakup of the sea ice in WHB since 2001 has been about one week later than it was before 1998 (Castro de la Guardia 2017; Cherry et al. 2013; Lunn et al. 2016).

If some polar bear struggle to survive this year it will be due to the late freeze-up date last fall combined with challenging winter conditions over Hudson Bay, not because of an early breakup of the sea ice.

And while it is certainly true that the overall trend in time spent onshore by WHB polar bears since 1979 has increased by about three weeks, the lack of a continued trend since 2001 is not what was expected or predicted, especially given the marked decline in global sea ice levels that have made headlines since 2007 (Crockford 2017), and the predictions of how devastating such low levels of ice would be to polar bears in areas like Hudson Bay that have to deal with a total disappearance of sea ice in summer and early fall.

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Longest-swimming polar bear lost less weight than if she had stayed onshore

Recent media hype over swimming polar bears in the Southern Beaufort has been quite spectacular (still going strong today at the Washington Post here) but a close look at relevant data shows the message is bogus. Researchers admit (in their methods section) they couldn’t tell if bears said to have swum “non-stop” actually hauled out for half a day or more to rest on small ice flows invisible to satellites and astonishingly, the bear getting all the media attention – who swam the longest of any bear – lost less weight than a bear would have done simply sitting on shore for the same length of time.

Washington Post_swimming polar bears_snapshot 21 April 2016

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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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Polar bears and melting ice: three facts that shouldn’t surprise you

If I was invited by USA TODAY to discuss how climate change is affecting polar bears now – summed up in three talking points – this is what I’d say. I’d use some meaningful images rather than cute pictures of cuddly bear cubs and I’d provide links to my work with references and details to back up my answers.

Compare my responses to those supplied by Steve Amstrup in his capacity as spokesperson for Polar Bears International (“Save our sea ice!”) to Jolie Lee at USA TODAY last week, who’s word is expected to be taken as gospel.

AK PB N Shore-USFWS Barrow_labeled

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Polar bear researchers still withholding Hudson Bay data

The latest polar bear propaganda emanating from The Guardian is unscientific nonsense fed to them by activist Canadian polar bear researchers: Polar bear numbers in Hudson Bay of Canada on verge of collapse.

This episode of Goldenberg’s polar bear grandstanding includes a photo caption with a totally unsubstantiated claim that some folks might call a lie:

Melting ice is cutting polar bears off from their food source in Hudson Bay, and death rates have soared.

“Death rates have soared”? Where are all the bodies? Show us the starving bears!

In fact, the ice of Hudson Bay melts every summer and always has done. When it does, polar bears go ashore and live off the many inches of stored blubber they put on during their spring feasting on fat baby seals. The last three years, the open-water season has been only about two weeks longer than it was in the 1980s. There has been no steady increase but lots of variability.

Below I dismantle the rest of this transparently political posturing ahead of the international polar bear forum next week.
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