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Sunday, August 26, 2012

Arctic sea ice and 'natural cycles'

It's a favorite climate change denier meme: "It's all natural cycles--the climate is always changing."

So, here is one of the things that is new.  A blogger has taken a graphic from a 2011 scientific paper (Kinnard et al) reconstructing the extent of Arctic sea ice for the past 1,450 years and updated it to show actual observations of the last 12 years:



(Minor caveat: This was posted to the Skeptical Science blog and an astute reader pointed out that it is exaggerated slightly--because of the time of year at which measurements were compared, 2012 should actually be about five dashes higher than it is in the graphic.)

I cannot help but note that this is yet another version of the "hockey stick" shape that shows up in many areas of climate research and that results from the speed with which humanity is impacting the Earth's climate (see, e.g., this similar graphic, in reverse, of surface temperatures of Lake Tanganyika over a similar time frame).

Anyone out there think the above graphic looks like a natural cycle?  If so, please send me a small sample of what you are smoking--I'd like to give it a try.

UPDATE 8/26/12: Joe Romm's excellent Climate Progress blog has an article today titled "Why the Arctic sea ice death spiral matters" that includes the graphic above (minus the extension to 2012) and much more.

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