View topic - Canadian polar bears - no climate crisis?

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PostPosted: March 29th, 2016, 8:39 am 
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Canadian polar bear populations have been reassessed, suggesting that previous population estimates were poorly done.

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Demographic and traditional knowledge perspectives on the current status of Canadian polar bear subpopulations

23 March 2016


"...we suggest that the current status of Canadian polar bear subpopulations in 2013 was 12 stable/increasing and one declining (Kane Basin). We do not find support for the perspective that polar bears within or shared with Canada are currently in any sort of climate crisis."

“...much of the scientific evidence indicating that some polar bear subpopulations are declining due to climate change-mediated sea ice reductions is likely flawed by poor mark–recapture sampling.”




http://onlinelibrary.wiley.com/doi/10.1 ... .2030/full

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PostPosted: March 29th, 2016, 10:14 am 
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This is not particularly surprising to me. I think there is little evidence that climate change is adversely affecting most polar bear populations, at least not yet. That is not to say that we won't see it in the future, particularly in southern populations (like south Hudson Bay) where the ice-free season might become too long to support ice-dependent bears.

It is important to note also that climate warming will also open up some habitat for polar bears that was previously marginal because of extensive multi-year ice coverage, which does not support large seal populations. I am thinking here about the High Central Arctic, areas like Norwegian Bay. These areas have much less multi-year ice than previously and probably better seal populations. The same is true for narwhal, beluga, walrus and bowhead populations, for which these areas were previously only accessible in some years.

Right now the most important factor affecting polar bear populations in Canada is human hunting pressure. That is being carefully managed so the outlook for most stocks in the medium term is rather good right now.

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PostPosted: March 31st, 2016, 11:36 am 
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Its my understanding that polar bear habitat is generally on the sea ice. If that sea ice is in decline it would stand to reason that we'd see more of them on the land as they probably don't have anywhere else to go. As a polar bear has traditionally been sustained by living on the sea ice one has to wonder how they can remain healthy outside their normal environment. How do they get the seals if there's no ice? [The Atomic Bulletin of Scientists (2012) forecast a year-round north west passage by 2030 - initially on the Russian side but will eventually be completely free of ice by 2060]. Not that far off...

I would assume that a scientific study would take this into account but we seem to call many things "science" these days even those that have a bias or preconceived perception (depending on who is funding the study) which of course is not a valid approach.
Sometimes what is rational is probably closer to the truth.


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PostPosted: March 31st, 2016, 1:08 pm 
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Keep in mind that the reason the bears are on the sea ice is to get to the seals on the sea ice. If there is less ice then the seals will be coming out of the water on land - which the seals couldn't get to before because the ice was in the way.

The net result may end up being more safe islands for seals that are too far offshore for the Bears to get to. However that may also result in a net increase in seal populations. As long as seals are coming out of the water where the Bears can eat them, then it won't really matter if that is on ice or on land.

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PostPosted: April 1st, 2016, 8:44 am 
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Unless Bridgette Bardot et. al. show up to protect those cute little seals from those big nasty polar bears!! :o :roll:

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PostPosted: April 1st, 2016, 10:40 am 
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Splake wrote:
Keep in mind that the reason the bears are on the sea ice is to get to the seals on the sea ice. If there is less ice then the seals will be coming out of the water on land - which the seals couldn't get to before because the ice was in the way.

The net result may end up being more safe islands for seals that are too far offshore for the Bears to get to. However that may also result in a net increase in seal populations. As long as seals are coming out of the water where the Bears can eat them, then it won't really matter if that is on ice or on land.


Polar bears feed almost exclusively on ringed seals, which are obligate ice breeders. Ringed seals almost never haul out on land and require landfast ice for breeding. As the climate warms, one might expect land breeding seals like gray and harbour seals to shift northward. At present, their distribution does not overlap very much with that of polar bears, although harbour seals do occur in low numbers in some areas of the Arctic.

mark m wrote:
Its my understanding that polar bear habitat is generally on the sea ice. If that sea ice is in decline it would stand to reason that we'd see more of them on the land as they probably don't have anywhere else to go. As a polar bear has traditionally been sustained by living on the sea ice one has to wonder how they can remain healthy outside their normal environment. How do they get the seals if there's no ice? [The Atomic Bulletin of Scientists (2012) forecast a year-round north west passage by 2030 - initially on the Russian side but will eventually be completely free of ice by 2060]. Not that far off...


Polar bears require seasonal sea ice coverage but do spend several months on land in the southern part of their range. During this period they live mostly off their fat reserves. So yes, if the ice free season gets longer, this will detrimentally affect polar bears in some areas. And, as I said, it will open up some marginal High Arctic habitat for them.

Kinguq


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