Hi,
a term used for species extinctions comes to mind - when a species is
reduced to such a small number of animals in the wild but isn't extinct,
it is sometimes referred to as 'functionally extinct'.
If we consider the functions of the Arctic sea ice - in areas it is
pretty near functionally extinct already... eg in Hudson Bay...
Sea ice performs so many different functions it's hard to even list them.
best wishes,
Emily.
On 18/07/2011 17:24, [email protected] wrote:
Ken (cc list)
I have tried (as a rank amateur observer, not participant) to
follow this retreatjng September arctic ice topic for the last 5
years. I have come to a different conclusion than expressed in your
two articles.. The website I have found most valuable can be located
by remembering the name "Neven" - and googling with "arctic" and "ice"
. This blog averages more than one message per hour - and the folks
commenting there seem to be putting a lot of time into the topic. Not
experts on this blog, but dedicated amateurs, who do seem to be
talking to the ice experts, however.
The key question is what are we to be measuring when we talk of
"gone"? I gather that 10% remainder is considered "gone". One also
has to consider whether one will be talking area, extent, or volume.
I like the volume definition - as thickness is dropping much more
rapidly than area (the smaller number) or extent - and the volume is
easier to find data on than thickness. A good (April 2011)
discussion of these differences is at
http://neven1.typepad.com/blog/2011/04/trends-in-arctic-sea-ice-volume.html#more
This short write-up, using experimental volume data, suggests about
2016 as a best guess to get to this 10% value. This uses a "Gompertz"
model - which has no particular theoretical validity - but seems to
have more validity than a linear or quadratic approach to absolute
zero. It might be overly conservative.
For today's blog exchange (several dozen so far today), go to just
the early part of the above URL.
The modeler who seems (to me) to have done the best job in modeling
this (the subject of Ken's two articles) is Dr. Wieslaw Maslowski who
has supported this 2016 "gone" date since 2008 or so (and again this
year). The following 2008 cite is given in the above URL for a
Maslowski Ppt:
http://www.ees.hokudai.ac.jp/coe21/dc2008/DC/report/Maslowski.pdf
His work doesn't show up in literature comparisons such as in
Ken's articles because his (highly detailed) model is limited only to
the Arctic; it is not a global model, although of course it is linked
to the rest of the world. We should also note that Maslowski has
supported 2013 as not being out of the question. (and still does)
I don't believe we have the luxury of relying on a "gone" date in
the 2030's or even 2020's - and this is based on interpretations of
recent data - not model outputs. It seems to me the lesson is that
the global models need retuning.
Ron
------------------------------------------------------------------------
*From: *"Ken Caldeira" <[email protected]>
*To: *"geoengineering" <[email protected]>
*Sent: *Monday, July 18, 2011 6:41:17 AM
*Subject: *[geo] September sea-ice gone by end of century? (or much
sooner)
Folks,
There has been a fair amount of discussion on this group that talks
about imminent September sea ice loss in the Arctic.
The attached paper indicates that around half of the normal September
sea-ice should still be around in the 2020-2040 time frame.
Boe, J., Hall, A., Qu, Z. Nature Geosci 2, 341-343 (2009).
I am not saying that the situation in the Arctic is not dire, however,
are the suggestions that September sea-ice in the Arctic is soon to be
a thing of the past a bit overblown and without foundation?
Best,
Ken
___________________________________________________
Ken Caldeira
Carnegie Institution Dept of Global Ecology
260 Panama Street, Stanford, CA 94305 USA
+1 650 704 7212 [email protected]
<mailto:[email protected]>
http://dge.stanford.edu/labs/caldeiralab @kencaldeira
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