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Topic Title: Polar Bear Attacks Increasing Due to Rising Temperatures caused by Climate Change
Topic Summary: Is sea ice extent in the Hudson Bay Area most influenced by Temperature or Surface Salinity?
Created On: 04 November 2013 05:21 PM
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 04 November 2013 05:21 PM
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Polar bear attacks: scientists warn of fresh dangers in warming Arctic

"Two people injured in latest attack as hungry bears deprived of access to sea ice increasingly look for food on land"

"The number of bear-human interactions, bear-human conflicts, may be somewhat on the rise," said Steven Amstrup, chief scientist for Polar Bears International."

" We have predicted in no uncertain times that as bears become hungrier as the sea ice absence period is longer, more and more of these animals are going to be venturing into communities, venturing into villages, raiding food caches, getting into garbage, and even attacking people. So we predict these kinds of events are going to be more frequent and more severe because of climate change."

This story is about Churchill, in Manitoba, Canada, (the polar bear capital of the world) on the shore of the Hudson Bay

The trouble for me in all this is that sea ice extent is not just a function of average temperature, it depends on other factors as well, most importantly the salinity of the surface layer of the sea. Surface salinity in the Hudson Bay will depend on wider precipitation levels and on the ice melt of the previous year(s) (amongst other things).

Other less likely factors may be river run-off changes, chemical or biological changes etc.

When you look at the data for ice extent the changes since the late 1960's are very clear; see Hudson Bay.

However looking at the climate data for Churchill in Manitoba, Canada; the data seems less clear

Data from 2012

Data from 1959

You can view the weather records for many years between the late 40's and this year.

It is very hard to see any sort of systematic shifts in average air temperatures over the last few decades in Churchill.

It would be interesting to see how surface salinity of the Hudson Bay has changed over the same 60 year priod, but I am not sure where to find this data. The sea ice changes may be partly due to wider precipitation shifts across the Hudson Bay area rather than solely being related to changes in average temperature across the region in the last few decades.

The polar bear experts may be right in other places with the causal chain:
Higher temperatures -> Less Sea Ice -> More Hungry Polar Bears -> More Polar Bear Attacks on Humans.

However I have a sneaking suspicion that the situation is slightly more complicated than this in the Hudson Bay area of North Eastern Canada.

Perhaps other people who know more about the climate history of this area could comment. The weather records from Churchill in the 1960's are incomplete; what was the reason for this?

James Arathoon

James Arathoon
 07 November 2013 01:21 AM
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What does this have to do with energy? Most likely cause of attacks being 'maybe somewhat on the rise' is more bears due to hunting bans and more people moving into the area for tourism. If sea ice does have an impact in a given year it seems that's more likely to be due to natural variations in winds, currents and weather rather than man-made emissions of CO2. Another one to add to the Warmlist of 800 spurious things blamed on man-made global warming.
 18 November 2013 07:08 AM
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Global warming is the inevitable trend of development of the earth

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