Not much change in sea ice coverage since last week – most of Hudson Bay is still covered with concentrated ice, which is good news for Western and Southern Hudson Bay polar bears. They are still free to roam and hunt over most of the ice-covered bay.
There may be slightly less ice than average for this time of year (Fig. 1, below) but coverage is still >70% with concentrated ice and does not appear to be melting quickly (see charts above and Fig. 2, below).
The dates for three previous earliest breakups according to Lunn and colleagues (Fig. 3) have come and gone, as all were in the first week of June (more on that in an upcoming post) – no records broken. More graphs and maps below, see previous posts here and here.
Posted in Life History, Sea ice habitat
Tagged breakup, Cherry, concentration, habitat, Hudson Bay, Hudson Strait, hunting, Lunn, polar bears, sea ice, Southern Hudson Bay, western hudson bay
I have a new paper out that explains a fundamental problem with polar bear conservation.
I’m convinced that a flawed and out-dated ecological concept — that sea ice, under natural conditions, provides a stable, predictable habitat — is what has allowed the present doom and gloom attitude of most polar bear specialists to develop.
Sea ice changes, of course, from season to season. However, the concept that sea ice is a stable habitat assumes that these seasonal changes are predictable and virtually the same from one year to the next – at least, similar enough that the differences are not responsible for causing marked declines in population size.
The assumption is that under natural, stable conditions populations of Arctic animals will either stay the same over time or increase. Biologists were taught at university that sea ice should be a stable habitat and as a result, they’ve glossed over evidence they collected to the contrary. [see recent posts here and here, for example]
Negative effects on populations of short-term natural variations in spring sea ice or spring snow cover on sea ice have been entirely ignored in modeled predictions of future conditions. The focus has been on summer ice extent.
I have summarized this evidence in a fully referenced, peer-reviewed essay that explores how the acceptance of this fallacy (“sea ice is a stable habitat”) has so skewed the conservation biology of polar bears that to outsiders it may look like a scientific integrity issue.
The summary and the essay are below (with embedded links and references). The Global Warming Policy Foundation (GWPF) has published the essay in their “Briefing Paper” series (#16, The Arctic Fallacy: Sea Ice Stability and the Polar Bear), which includes a must-read foreword by Dr. Matthew Cronin, Professor of Animal Genetics at the University of Alaska Fairbanks. Press release here, pdf here.
I think you’ll find it timely and thought-provoking.
Posted in Conservation Status, Sea ice habitat
Tagged Beaufort Sea, climate change, Cronin, ecology, global warming, GWPF, habitat, Hudson Bay, IUCN Polar Bear Specialist Group, K-selection, model, PBSG, polar bear, Polar Bears International, polarbearscience, population size, predictions, ringed seal, sea ice, snow depth, stable, summer, thick spring ice, variability
Is breakup imminent for Hudson Bay sea ice? Probably not, but this year more than ever, it will depend on how you define it. Despite a large patch of open water in western Hudson Bay (CIS chart above, for 1 June), there is still more than 70% sea ice coverage over the entire bay as of this week, when you use the standard breakup definition of 50% ice coverage (Fig. 1). Ice remaining over the bay is mostly 90% or greater, as the chart above shows – which means there is still a lot of polar bear hunting habitat remaining.
Figure 1. Sea ice coverage over Hudson Bay, as a percentage, for the week of 4 June, 1971-2015. Click to enlarge.
The interconnected region of Hudson Bay, Hudson Strait, and southern Davis Strait (Fig. 2), what the Canadian Ice Service calls “Regional Hudson Bay,” is only slightly below average for the week of 4 June.
Figure 2. Regional Hudson Bay, week of 4 June. Click to enlarge.
Since ice concentration is factored into breakup date calculation, a record-early breakup is simply not possible, since the previous record date (2 June, for 1990) has already passed. It might be an earlier than average breakup year but not very early, based on the 50% coverage definition (Fig. 3, below). This year, because of the unusual pattern of breakup of Hudson Bay ice, it will be critical for polar bears which definition of breakup is used – the old, 50% method (adopted because it’s what sea ice professionals used) or the newest one, which was determined to be most relevant to WHB polar bears (Cherry et al. 2013).
UPDATE 6 June 2015: I’ve added the forecast for ice conditions over the summer for North America (which for these folks includes June because it’s aimed at temperate NA, polar bear folks call June the end of spring), provided by the Canadian Ice Service: “Seasonal outlook for North American Arctic Waters issued by the North American Ice Service on 2 June 2015” [points of potential interest marked] The sea ice forecast (Table 1) for southwestern Hudson Bay (where most western and southern Hudson Bay polar bears come ashore) is for complete ice melt by 1 Aug, eight days later than the earliest date over the period 1968-2013. Time will tell if that’s what happens.
Posted in Advocacy, Sea ice habitat
Tagged breakup, Cherry, Churchill, climate change, Derocher, global warming, Lunn, Polar Bears International, polarbearscience, sea ice, western hudson bay
Polar bear habitat in the Southern Beaufort for May 2015 was a contrast between the development of recurring polynyas (patches of open water) and tremendously thick sea ice. So it’s interesting to see where the polar bears tagged by USGS biologists chose to hang out.
The total number of bears being tracked in May – 23 – is down markedly from the 30 bears USGS biologists started with in April.
Most of the collared bears were concentrated in May along the shore lead (crack of open water) that normally develops between the shorefast ice and the pack ice offshore. That’s especially understandable this year, since most of that pack ice is 3-5 m thick (10-16 ft) – see the maps below.
Posted in Sea ice habitat
Tagged Beaufort Sea, Chukchi Sea, habitat, open water, polar bear, polynya, satellite collars, sea ice, shore lead, spring sea ice, thick ice, tracking, USGS