In contrast to summer sea ice, winter ice in the Arctic was again abundant this year. The slight decline since 1979 has so far been no cause for concern to polar bears, who are thriving.

The fact that multiyear sea ice got thinner between 2018 and 2021 as documented by a new study, is ultimately good news for polar bears: less multiyear ice compared to first year ice is better for all marine mammals in the Arctic. Polar bears and seals, for example, are dependent on the seasonal ice that forms every winter (Atwood et al. 2016; Durner et al. 2009). Multiyear ice is simply too thick for any purpose except as a summer refuge for polar bears (for which land will do just as well) and a platform for maternity dens over the winter, for which thick first year ice will often do just as well (Anderson et al. 2012; Rode et al. 2018).
Continue readingComments Off on Good news for polar bears and seals: new study finds multiyear Arctic sea ice is getting thinner
Posted in Life History, Sea ice habitat
Tagged first year ice, ice thickness, Last Ice Area, multiyear ice, polar bears
Polar bear populations in most of the Canadian Arctic Archipelago (CAA) must be booming, as they are elsewhere. That’s because the ‘experts’ were even more wrong in their predictions of future sea ice conditions than most people realize: they expected the CAA would remain choked with ice during a ‘nearly ice-free’ summer driven by human-caused global warming.
Map presented by Wang and Overland (2012: Fig 3) shows what these experts thought a ‘nearly ice-free’ summer would look like, which they expected to occur by 2030 or so.
Look at the map from Wang and Overland (2012) above, which is what they thought a ‘nearly ice-free’ summer would look like in the year 2030 or so.
Wang and Overland used the same models used by USGS biologists to predict the future survival of polar bears based on habitat loss (Amstrup et al. 2007; Atwood et al. 2016; Durner et al. 2007, 2009). Note the thick ice in the CAA — what USGS experts call the ‘Archipelago’ sea ice ecoregion (denoted by white in the map), indicating ice about 1 metre thick (2-3 feet) — expected to remain at the height of summer in 2030.
The problem is that ice in this region has been largely absent most summers since 2006, even though overall ice extent has been much more extensive than expected for a ‘nearly ice-free’ summer, as I show below.
This is not another “worse than we thought” moment (Amstrup et al. 2007) — this is sea ice models so wrong as to be useless: failed models used to inform future polar bear survival models that got the bears declared ‘threatened’ with extinction in the US in 2008 (Crockford 2017).
It also means polar bears are almost certainly doing much better than recent population counts indicate, since only one subpopulation out of the six in the CAA has recently been assessed. But since polar bear specialists have consistently underestimated the adaptability of this species and the resilience of the Arctic ecosystem to respond to changing conditions, it’s hard to take any of their hyperbole about the future of polar bears seriously. Continue reading
Comments Off on Experts’ vision of an ice-free summer is already wrong & benefitting polar bears
Posted in Conservation Status, Population, Sea ice habitat
Tagged Canadian Arctic Archipelago, Crockford, first year ice, Gulf of Boothia, ice-free, IUCN Polar Bear Specialist Group, IUCN Red List, Kane Basin, Lancaster Sound, multiyear ice, Northwest Passage, PBSG, predictions, sea ice, wrong
To counter the misleading ploy used by the Sunday Times — of implying polar bears are in peril because of recent changes in Arctic sea ice (Sunday Times & The Australian, 21/22 Sept. 2014 Arctic ice cap in a ‘death spiral’) — I’ll go over again why the polar bear as a species is not threatened by declines in summer sea ice or even winter ice that is predominantly “thin” (first year) ice.
Graphic above from the Sunday Times, September 21, 2014
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Comments Off on Polar bears are not in peril due to recent sea ice changes
Posted in Conservation Status, Sea ice habitat, Summary
Tagged Arctic ice cap, arctic sea ice, Chukchi Sea, death spiral, denning females, evidence, first year ice, ice thickness, ice-free Arctic, Mark Serreze, North Pole, Peter Wadhams, polar bear, sea ice extent, thin sea ice
On Monday, March 25, the National Snow and Ice Data Center (NSIDC) announced that March 15 2013 was likely the maximum extent reached this winter. Note that just a few days ago, I discussed the relationship between maximum extent of sea ice and the global distribution of polar bears around the Arctic (see March 20th post here).
Comments Off on Sea ice maximum reached March 15: what it means for polar bears
Posted in Sea ice habitat
Tagged first year ice, ice thickness, Newfoundland, NSIDC, polar bears, ringed seals, sea ice extent, shorefast ice, winter ice maximum
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