September sea-ice gone by end of century? (or much sooner)
Ken Caldeira
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 kcal...@carnegie.stanford.edu
http://dge.stanford.edu/labs/caldeiralab @kencaldeira
rongre...@comcast.net
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" <kcal...@carnegie.stanford.edu>
To: "geoengineering" <geoengi...@googlegroups.com>
Sent: Monday, July 18, 2011 6:41:17 AM
Subject: [geo] September sea-ice gone by end of century? (or much sooner)
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Emily
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.
> ------------------------------------------------------------------------
> *From: *"Ken Caldeira" <kcal...@carnegie.stanford.edu>
> *To: *"geoengineering" <geoengi...@googlegroups.com>
> *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 kcal...@carnegie.stanford.edu
> <mailto:kcal...@carnegie.stanford.edu>
Mike MacCracken
extinct) that when there are no more in a region or in the wild, the
appropriate term is (from biology online):
Extirpation
The act of extirpating or rooting out, or the state of being extirpated;
eradication; excision; total destruction; as, the extirpation of weeds from
land, of evil from the heart, of a race of men, of heresy.
Extinction only applies when there are none either in the wild or in
captivity.
I am not sure that applying this word to sea ice would work very well,
however.
Mike MacCracken
Emily
thanks, extinct, I think means it isn't in the wild or captivity for 30
years... which is a long time to wait.
The point I'm making is that other terms are created when there is
little sense in waiting for 30 years for non existence to exist...
The point about sea ice, is an important one. Communicating an issue is
key. If, as is possible, that some sea ice remains in pockets or as a
thin film over the Arctic in areas at some times of the year, do we wait
before accepting that the ecosystem is functionally, well, dysfunctional?
I think a term can be adopted in this case, which refers to the sea ice
as so severely reduced that it is no longer performing its critical
previous functions.
Communicating in phrases and terms which are accurate but also readily
accessible is key. I am not sure what the correct phrase for the
diminishing sea ice is, and I am hopeful that we wont need one. I am
optimistic that we will restore the Arctic ecosystem, just as we re
plant a forest when we realise we need it, we clean up an oil spill, and
we clean up a coal spoil heap.
thanks so much,
Emily.
Mike MacCracken
marine animals, for indigenous communities on barrier islands (absence means
less suppression of winter storm waves), indigenous hunting at certain times
of the year is disrupted, disruption of the creation of the very cold air of
the Arctic in some seasons (so we have a longer season with the Arctic
supplying a lot of heat to the atmosphere and affecting the weather in
mid-latitudes), etc.
Even thin ice or shorter ice-in situations leads to dysfunction--we don't
have to wait until 100% is gone in a particular season, etc.
Mike
Emily
now we need a way to communicate this.
A few years ago, we moved from talking about the extent to depth and volume.
Perhaps this September, a new narrative can emerge about the
functionality of the sea ice rather than the extent.
I think this reinforces the need for active intervention to stabilise
the Arctic and restore the sea ice, or at least its functionality.
very best wishes,
Emily.
Andrew Revkin
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Veli Albert Kallio
Date: Mon, 18 Jul 2011 13:04:34 -0400
Subject: Re: [geo] September sea-ice gone by end of century? (or much sooner)
From: rev...@gmail.com
To: kcal...@gmail.com
CC: geoengi...@googlegroups.com
Eugene Gordon
At last some sanity.
From: geoengi...@googlegroups.com [mailto:geoengi...@googlegroups.com] On Behalf Of Andrew Revkin
Sent: Monday, July 18, 2011 1:05 PM
To: kcal...@gmail.com
Cc: geoengineering
Subject: Re: [geo] September sea-ice gone by end of century? (or much sooner)
Andrew Lockley
Schaeffer et al have already estimated c fluxes from permafrost at ~1.8Gtpa over coming decades. Some of these fluxes may be methane, and the process will be accelerated by feedbacks
However, it is likely of course that premature thaw of the arctic will accelerate this process.
I wonder if anyone can hazard a guess at the new c fluxes we might have to face as a result of the rapid sea ice loss currently observed?
A
>
> I would just ask people to draw attention to sea ice volume models. In addition to look at i.e. Cryosphere Today how the terrestrial defrost progressed this year, and check out temperature legend maps for North Canada and Siberia. How many natural processes behave the same way on their very last legs as they do in the mid journey. Almost none.
>
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David Appell
about 12 years:
http://davidappell.blogspot.com/2011/07/arctic-ice-is-at-record-low.html
David
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John Nissen
I disagree with your estimation of 12 years and suggest 5 years is more likely and could even be optimistic, at least for September sea ice decline to below the 10% mark.
The PIOMAS graph, updated to end June 2011 here [1], made me think that 2016 was the most likely date, fitting a curve rather a straight line because of positive feedback. This is confirmed by Ron Larson from his analysis, see earlier in thread. You have to work out what the y-axis anomaly represents. When we get to -14 thousand km-3, which is a gnat's whisker below the line across the bottom of the graph, I estimate that we'd have less than 10% of ice volume left in September. Unfortunately [1] does not give you the vital data as to what the total sea ice volume is that they are measuring anomaly against! However, you can see that this year is almost as down on 2007 as 2007 was on the 1979-2010 average. If we assume that September 2007 was 40% down on the 1979-2010 average (which was true for the area), the 2011 could be almost 80% down. We only need to reach 90% down to have 10% sea ice volume left, that Ron talks about as being a critically low level. That makes the 2016 date seem quite reasonable, if not optimistic!
Peter Wadhams points out that the sea ice thickness is decreasing faster than the sea ice extent. These trends are of course masked by much wind and weather variability from year to year, which affects ice flow, not just direct melting. This explains why one can have had relatively little change in the minimum sea ice extent since September 2007, although the volume has been declining.
64 trillion dollar question*
If geoengineering is to have a good chance to save the Arctic sea ice, then it needs to be deployed quickly, building up to maximum strength by summer 2013. By then the Arctic annually-averaged radiative forcing of the "albedo flip" (as ice/snow reflection of sunlight turns to sea/land absorption of sunlight) may exceed 10 Watts per square metre [2]. Could a combination of SRM methods, with deployment ramped up as fast as possible, have a chance to exceed 10 W/m-2 of negative forcing in the Arctic by summer 2013, in order to halt Arctic warming and save the Arctic sea ice?
Note that cloud brightening and other SRM methods could contribute to negative forcing by cooling the water flowing into the Arctic, especially the currents from the North Atlantic. So cooling does not have to be directly of the Arctic itself.
Cheers from Chiswick,
John
* P.S. It's a 64 trillion dollar question if you consider that losing the sea ice could have repercussions affecting the total global GDP, which is around that value.
[1] http://psc.apl.washington.edu/wordpress/research/projects/arctic-sea-ice-volume-anomaly/
[2] http://www.mail-archive.com/geoengi...@googlegroups.com/msg00660.html
[geo] Re: Geoengineering - cloud effects
John Nissen
Wed, 10 Dec 2008 13:42:10 -0800