Arctic refreeze is well underway. Less than half way through the Arctic autumn (Oct-Dec), polar bear habitat on 11 November 2015 covered the same total area as it did on the last day of Arctic spring (April-June); it’s just distributed differently.
Yesterday, courtesy NSIDC Masie
Here is what 30 June 2015 ice extent looked like, with the same amount of ice coverage:
For the week of 12 November, Hudson Bay sea ice development is well underway, with more ice in the north than there has been in many years; Davis Strait ice is the highest this week since 1999 and Baffin Bay ice coverage is above average. Foxe Basin and the Beaufort Sea are both approaching maximum coverage, which means bears there will be back out on the ice hunting. Chukchi Sea ice has finally surrounded Wrangel Island but the Svalbard Archipelago in the Barents Sea is still ice-free. More ice maps and charts below.
There may not be ice for Western Hudson Bay polar bears to walk on yet but there is still more ice forming along the northwest shore of the bay than last year at this time or even the year before. The Canadian Ice Service (CIS) map for 5 November shows this early formation.
What’s present is mostly grey ice defined by CIS as:
“Young ice 10-15 cm thick, less elastic than nilas [a kind of new ice] and breaks on swell. It usually rafts under pressure.”
Polar bears generally need ice about 30 cm thick to support their weight, which could take a day or two – or a week or two, depending on the weather in northwestern Hudson Bay. For Churchill, along the central coast of western Hudson Bay, ice thick enough for walking will not likely be far behind, given the long-range forecast of freezing weather. In recent years, most Churchill polar bears have left the ice by around 20 November. More maps and graphs for this week below.
Great news for Western Hudson Bay polar bears! Following up from sea ice conditions last week, CIS maps show ice forming all along western Hudson Bay – not a huge amount, but the beginning of the end of the ice-free season, which recently has not occurred until mid-November (Cherry et al. 2013).
There is above-average sea ice coverage in Foxe Basin and Davis Strait, and only slightly below average coverage in the Beaufort Sea (see graphs below). Polar bear habitat is shaping up very nicely indeed across Canada and the US this year.
Now, not so much. Here is a 16- year old CBC TV special on Churchill polar bears – listen to Ian Stirling and reporter Eve Savory use the early breakup of sea ice on Hudson Bay in 1999 to hype the alarm about Western Hudson Bay polar bears. Watch Stirling in action darting and measuring bears and bemoaning the good old days of the 1980s, claiming the “bears are sending a signal from the ecosystem.”
Watch this archived copy of “The Shrinking Bears of Hudson Bay” and compare his claims to what has actually happened in the 16 years since then. It runs just over 15 minutes.
“Just as the ice is shrinking in Hudson Bay, so are its polar bears. Climate change has shortened the season for winter ice, a crucial period for the bears to feast on seals and build up their fat reserves. And so, over the 18 years that wildlife biologist Ian Stirling has been studying them, the polar bears have become skinnier and their offspring fewer. In this 1999 report for CBC-TV’s The National, Stirling says once their habitat is gone, there’s nowhere else the Hudson Bay polar bears can go.” [my bold – see notes below]
• Program: The National [Canadian Broadcasting Company, CBC]
• Broadcast Date: Sept. 23, 1999
• Duration: 16:39
Stirling has continue to make these claims since 1999, yet no updated evidence has been provided. There is no plausible evidence that the decline of polar bear numbers in Western Hudson Bay was due to sea ice changes caused by human-caused global warming (Crockford 2015) or that continued declines in condition of bears or litter size have occurred. Note that the latest survey of Western Hudson Bay polar bears found no trend in either breakup or freeze-up dates since 2001 (Lunn et al. 2013) and that the population is now stable.
Ice coverage charts and breakup dates graph below, for context.
UPDATE ADDED – see below
Posted in Life History, Sea ice habitat
Tagged body condition, breakup, CBC, Churchill, climate change, freeze-up, global warming, Hudson Bay, litter sizes, polar bear, population estimate, sea ice, Shrinking Bears, Stirling, western hudson bay
At this time of year, sea ice extent numbers are meaningless for polar bears. The extreme low September minimum of 2012 – when masses of polar bears didn’t die – showed rational people that this is true. Even the low 2007 summer extent, which hit earlier in the season than 2012, had little to no negative impact.
In late summer, bears outside the Canadian Archipelago either retreat to shore or stay on the sea ice as it retreats north into the Arctic Basin (see image below, click to enlarge). Most bears in the Archipelago have ice year round, so life doesn’t change much. This means that it does not matter to polar bears how much area the Arctic Basin ice covers in September – for their needs, 1.0 mkm2 would be plenty.
Still, Southern Hudson Bay polar bears had extended hunting opportunities in July this year (whether or not they hunted successfully) and for this date, Hudson Bay had more ice remaining than any year on record. Yes, more than even 1992 but only by a few percent. See charts and maps below.
Posted in Life History, Sea ice habitat
Tagged Arctic basin, fasting, habitat, Hudson Bay, MASIE, minimum, passive microwave, polar bear, sea ice, September, starving, summer, thin ice
From the CBC this morning, we have the report of a female polar bear and her cub paying a visit to an Nunavut campsite near Chesterfield Inlet in northwestern Hudson Bay, which is technically within the boundary of the Foxe Basin polar bear subpopulation.
Maggie Putulik photo, 29 July 2015 Chesterfield Inlet, Nunavut.
These are not the desperate bear victims of global warming we have been warned about by polar bear specialists but well-fed curious ursids not averse to an easy meal if there’s one to be had. Such bears are easily deterred by a loud noise. Note this was the second visit by polar bears this Nunavut family had experienced at this location within a three-week period – two other bears had stopped by earlier. Note that ice in this region of Hudson Bay broke up earlier than usual this year yet these bears seem to be in fine condition and can expect the first fall ice of the season (freeze-up) to appear in their neighbourhood, see maps below.
Posted in Polar bear attacks, Sea ice habitat
Tagged breakup, CBC, Chesterfield Inlet, cub, Foxe Basin, freeze-up, Hudson Bay, Nunavut, onshore, polar bear, problem bears, Putulik, sea ice, summer
Since 1971, there has been no year when there was as much ice left on Hudson Bay as there is this year at August 13th, except 1992 – the year when Mt. Pinatubo seemingly affected Hudson Bay ice levels but not any other region in Eastern Canada or the Beaufort Sea. Odd, that – see the graphs below.
Doesn’t mean that much to polar bears, since they will mostly be fasting whether they are onshore for the summer or riding the ice – they primarily live off their fat this time of year. Still, the relative ice levels are interesting because it could impact freeze-up dates later this fall, which will influence the bears’ ability to hunt before the winter fast sets in.