Today I’ll discuss the response by Polar Bears International representative Steven Amstrup to a comment submitted during their recent “webchat” at The Guardian (Wednesday, November 6), which had to do with the fact that polar bears survived warm periods in the geological past, particularly interglacials.
[Here’s a pdf file of all the questions that were answered by PBI staff: PBI webchat Q&A, also available here]
This is the comment (the first portion of #4 on my list), submitted by MarkBLR:
There was a paper in Science magazine last year (link …) indicating that polar bears became a distinct species about 600kya (+/- 300k years).
This means that they have survived at least two (and possibly eight) previous inter-glacials, in particular the Eemian (130kya to 110kya), when temperatures in the Arctic were 5 to 8 degrees Celcius warmer than current temperatures for several thousand years.
Note that their numbers apparently decreased significantly during the Eemian, and slowly increased as temperatures cooled, but “climate change” was not enough on its own to make them extinct. [my bold]
[We can perhaps forgive Mark for not being able to spell “Celsius” correctly, but Amstrup (see below) has no excuse. The paper in Science Mark refers to is Hailer et al. 2012, discussed in a previous post here. Note that the actual question Mark asked is not included here because Amstrup responded to this portion of his comment only]
Amstrup tries to convince Mark and other readers that polar bear resilience through Eemian warming is irrelevant to the issue of future survival, which I’ll demonstrate is not the case at all.
Here is what Amstrup had to say:
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