Assumptions in Polar Bear Populations

Rustee

5-8-2008 1:05 AM

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<div style="margin: 12px 0px; font-family: arial; color: #333333; background: #ffffff; border: solid 4px #e5e5e5; width: 100%; clear: left;"><div class="CM_CTB_Content_Wrap" style="margin: 0px; padding: 0px;background-color: #ffffff;"><div style="border-bottom: solid 1px #dcdcdc; white-space: nowrap; margin-bottom: 8px; background-color: #eeeeee ;background-image: url(http://clipmarks.com/images/source-bg.gif); background-repeat: repeat-x; height: 24px; line-height: 24px; vertical-align: middle; padding-bottom: 4px; color: #666666; font-size: 10px;" ><a href="http://clipmarks.com/clip-to-blog/" title="see clips that are hot right now"><img src="http://content.clipmarks.com/blog_embed/a3f21922-704f-4d8c-a15a-708b3b053383/37C1A6E4-D0AB-4300-9AC8-1A15643B85EA/" alt="" width="19" height="19" border="0" style="vertical-align: middle; margin: 0px 4px; display: inline; border: none; float:none;" /></a>clipped from <a title="http://www.aei.org/publications/pubID.27918/pub_detail.asp" href="http://www.aei.org/publications/pubID.27918/pub_detail.asp" style="font-size: 11px;">www.aei.org</a></div><blockquote style="text-align: left; padding: 0px 8px; margin: 4px 0px 8px 0px; background: transparent; border: none;" cite="http://www.aei.org/publications/pubID.27918/pub_detail.asp">The first assumption is that global warming has caused, and will cause, a predictable reduction in sea ice. The second assumption holds that polar bear populations will dwindle because they are dependent on sea ice to hunt for prey. But each of these assumptions is fraught with problems.</blockquote><div style="height: 2px; font-size: 2px; background: #dcdcdc; border-bottom: solid 1px #f5f5f5; margin: 2px 4px;"></div><blockquote style="text-align: left; padding: 0px 8px; margin: 4px 0px 8px 0px; background: transparent; border: none;" cite="http://www.aei.org/publications/pubID.27918/pub_detail.asp">But the IPCC projections are based on the assumption that Arctic ice melting is the result of global warming caused by greenhouse gas emissions--an assumption that was recently shown to be of dubious merit by NASA, which is hardly a hotbed of climate skepticism.</blockquote><div style="height: 2px; font-size: 2px; background: #dcdcdc; border-bottom: solid 1px #f5f5f5; margin: 2px 4px;"></div><blockquote style="text-align: left; padding: 0px 8px; margin: 4px 0px 8px 0px; background: transparent; border: none;" cite="http://www.aei.org/publications/pubID.27918/pub_detail.asp">Son Nghiem explained that the warming of recent years was, in fact, caused by a change in wind patterns. </blockquote><div style="height: 2px; font-size: 2px; background: #dcdcdc; border-bottom: solid 1px #f5f5f5; margin: 2px 4px;"></div><blockquote style="text-align: left; padding: 0px 8px; margin: 4px 0px 8px 0px; background: transparent; border: none;" cite="http://www.aei.org/publications/pubID.27918/pub_detail.asp">Thus, to determine whether polar bears will be endangered by the disappearance of sea ice, trends in population are predicted using something called population viability analysis (PVA)</blockquote><div style="height: 2px; font-size: 2px; background: #dcdcdc; border-bottom: solid 1px #f5f5f5; margin: 2px 4px;"></div><blockquote style="text-align: left; padding: 0px 8px; margin: 4px 0px 8px 0px; background: transparent; border: none;" cite="http://www.aei.org/publications/pubID.27918/pub_detail.asp">PVA can be a useful tool in policy cost-benefit analysis, but its results are only as accurate as the data and the model assumptions that go into it. </blockquote></div><div style="margin: 0px 6px 6px 4px;"><table style="font-size: 11px;border-spacing: 0px;padding: 0px;" cellpadding="0" cellspacing="0" width="100%"><tr><td style="background:transparent;border-width:0px;padding:0px;">&nbsp;</td><td align="right" style="background:transparent;border-width:0px;padding:0px;width:107px" width="107"><a href="http://clipmarks.com/share/37C1A6E4-D0AB-4300-9AC8-1A15643B85EA/blog/" title="blog or email this clip"><img src="http://content7.clipmarks.com/images/c2b-foot.png" border="0" alt="blog it" width="107" height="17" style="border-width:0px;padding:0px;margin:0px;" /></a></td></tr></table></div></div>

Rustee says:

What we do know about polar bears is that, contrary to media portrayals, they are not fragile "canary in the coal mine" animals, but are robust creatures that have survived past periods of extensive deglaciation. Polar bear fossils have been dated to over one hundred thousand years, which means that polar bears have already survived an interglacial period when temperatures were considerably warmer than they are at present and when, quite probably, levels of summertime Arctic sea ice were correspondingly low.

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