In discussing what defines "functionally extinct" ice, it's also clear that the term "ice-free arctic" is not well defined: if ice "extent" is generally defined as the area with >15% continuous ice cover, then the whole arctic as "ice free" seems to be starting to get defined in some circles as that percentage cover (which itself seems somewhat arbitrary, and, I believe, originates from issues of navigability and not from any 'vital functions') being confined to 1 million sq km. From a recent paper, (Wang and Zhang, 2010):
Following Wang and Overland (2009), the ice-free state is defined as occurring when the total September Arctic Ocean sea ice extent, the area with a sea ice concentration ≥15%, is less than 1 million km2. This cutoff is used because models suggest that even when the Arctic can be considered ‘‘nearly sea ice free’’ at the end of the summer, the regions north of Greenland and Canada will still retain some sea ice. But in the Boe et al paper that Ken posted, this doesn't seem to have been followed, and perhaps partly thus the low probability of "ice-free" conditions coming soon? - On the basis of our approach, there is a probability of 16% that at least 20% of the baseline sea-ice cover in September remains at the end of the twenty-first century and the same probability that the ice disappears completely by 2046-2065. And since all of this only concerns "extent" and not volume, and yet we know that thickness is vital to stability, isn't this really all just a house of cards, as far as accurately predicting the future path of the arctic? I agree with Ron about Maslowski.......... Cheers, Nathan On Tue, Jul 19, 2011 at 7:39 AM, <[email protected]>wrote: > Today's Topic Summary > > Group: http://groups.google.com/group/geoengineering/topics > > - September sea-ice gone by end of century? (or much > sooner)<#1314231fd53034d0_group_thread_0>[9 Updates] > > Topic: September sea-ice gone by end of century? (or much > sooner)<http://groups.google.com/group/geoengineering/t/d416291f7ce28ab7> > > Ken Caldeira <[email protected]> Jul 18 02:41PM +0200 > ^<#1314231fd53034d0_digest_top> > > 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] > http://dge.stanford.edu/labs/caldeiralab @kencaldeira > > > > > [email protected] Jul 18 04:24PM ^<#1314231fd53034d0_digest_top> > > 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 > ----- Original Message ----- > 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] > http://dge.stanford.edu/labs/caldeiralab @kencaldeira > > > -- > You received this message because you are subscribed to the Google > Groups "geoengineering" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]. > For more options, visit this group at > http://groups.google.com/group/geoengineering?hl=en. > > > > > Emily <[email protected]> Jul 18 08:53PM +0100 > ^<#1314231fd53034d0_digest_top> > > 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. > > > > > > > Mike MacCracken <[email protected]> Jul 18 04:50PM -0400 > ^<#1314231fd53034d0_digest_top> > > For species, I have heard (e.g., from reviewers when I have misused the > word > 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 <[email protected]> Jul 18 10:00PM +0100 > ^<#1314231fd53034d0_digest_top> > > hi > 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. > > On 18/07/2011 21:50, Mike MacCracken wrote: > > > > > Mike MacCracken <[email protected]> Jul 18 05:16PM -0400 > ^<#1314231fd53034d0_digest_top> > > The sea ice is already becoming dysfunctional in a number of ways--for > some > 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 <[email protected]> Jul 19 07:26AM +0100 > ^<#1314231fd53034d0_digest_top> > > absolutely. > > 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. > > On 18/07/2011 22:16, Mike MacCracken wrote: > > > > > Andrew Revkin <[email protected]> Jul 18 01:04PM -0400 > ^<#1314231fd53034d0_digest_top> > > > > http://dotearth.blogs.nytimes.com/2010/03/22/new-light-shed-on-north-pole-ice-trends/ > > The bottom line, expressed here before, is that no one should expect to > find > much broad meaning in short-term variability in Arctic sea ice — in one > direction or the other. If there is a death spiral, expect a lot of > loop the > loops< > > http://dotearth.blogs.nytimes.com/2009/10/06/spread-of-thicker-arctic-ice-seen-last-summer/ > >along > the way. Those most passionately pushing for and against action on > greenhouse gases have a tendency to jump to the National Snow and Ice > Data > Center Web site to chart each wiggle. > > > > > [email protected]. > > For more options, visit this group at > > http://groups.google.com/group/geoengineering?hl=en. > > -- > *Please excuse typos; as you may be aware, I had a stroke 1 > July<http://dotearth.blogs.nytimes.com/2011/07/01/time-for-a-checkup/> > .* > > ANDREW C. REVKIN > Dot Earth blogger, The New York Times > http://www.nytimes.com/dotearth > Senior Fellow, Pace Acad. for Applied Env. Studies > Cell: 914-441-5556 Fax/voicemail: 509-357-0965 > Twitter: @revkin Skype: Andrew.Revkin > > > > > Veli Albert Kallio <[email protected]> Jul 19 08:43AM > ^<#1314231fd53034d0_digest_top> > > 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. > > > > > > > Date: Mon, 18 Jul 2011 13:04:34 -0400 > Subject: Re: [geo] September sea-ice gone by end of century? (or much > sooner) > From: [email protected] > To: [email protected] > CC: [email protected] > > > > http://dotearth.blogs.nytimes.com/2010/03/22/new-light-shed-on-north-pole-ice-trends/ > > > The bottom line, expressed here before, is that no one should expect to > find much broad meaning in short-term variability in Arctic sea ice — in > one > direction or the other. If there is a death spiral, expect a lot of loop > the > loopsalong the way. Those most passionately pushing for and against action > on greenhouse gases have a tendency to jump to the National Snow and Ice > Data Center Web site to chart each wiggle. > > > > > > On Mon, Jul 18, 2011 at 8:41 AM, Ken Caldeira < > [email protected]> wrote: > > 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] > http://dge.stanford.edu/labs/caldeiralab @kencaldeira > > -- > You received this message because you are subscribed to the Google > Groups "geoengineering" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]. > For more options, visit this group at > http://groups.google.com/group/geoengineering?hl=en. > > > -- > Please excuse typos; as you may be aware, I had a stroke 1 July.ANDREW > C. REVKINDot Earth blogger, The New York Times > http://www.nytimes.com/dotearthSenior Fellow, Pace Acad. for Applied > Env. StudiesCell: 914-441-5556 Fax/voicemail: 509-357-0965 Twitter: > @revkin Skype: Andrew.Revkin > > -- > You received this message because you are subscribed to the Google > Groups "geoengineering" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]. > For more options, visit this group at > http://groups.google.com/group/geoengineering?hl=en. > > > > -- > You received this message because you are subscribed to the Google Groups > "geoengineering" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]. > For more options, visit this group at > http://groups.google.com/group/geoengineering?hl=en. > -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/geoengineering?hl=en.
