[CRYOLIST] When is a glacier no longer a glacier?

SUSAN digbycarsey at comcast.net
Wed Aug 15 20:02:44 PDT 2018


From: Frank Carsey
To: Cole Green-Smith, Oerlemans, J. (Hans), Jeffrey Kargel
Cc: cryolist at lists.cryolist.org
Sent: August 15, 2018 at 10:40 AM
Subject: Re: [CRYOLIST] When is a glacier no longer a glacier?

Jeff’s comments and Hans’ succinct observation also serve to highlight a wonderful reality: Glaciology is a healthy, dynamic and lively science. This energy is so nice for me to witness as a noncombatant. “If I am not here for breakfast, geologize at will.” (John Ciardi)
Cheers
Frank Carsey

Sent from XFINITY Connect App



------ Original Message ------

From: Jeffrey Kargel
To: Cole Green-Smith, Oerlemans, J. (Hans)
Cc: cryolist at lists.cryolist.org
Sent: August 15, 2018 at 8:36 AM
Subject: Re: [CRYOLIST] When is a glacier no longer a glacier?

Cole:
Of course science is merely the best thing around to describe reality at a level enough to act rationally on the information. All the rest falls into the categories of wishes, guesses, and other forms ofirrationality or stabs-in-the-dark. So of course when trying to describe reality using imperfect or impreciselanguages and equations that are approximations, there will be differences between science and reality. And there will also always be differing approaches... a great strength of science.
--Jeff


From: CRYOLIST<cryolist-bounces at lists.cryolist.org>on behalf of Cole Green-Smith<cole.greensmith at gmail.com>
Sent: Wednesday, August 15, 2018 3:15 PM
To: Oerlemans, J. (Hans)
Cc: cryolist at lists.cryolist.org
Subject: Re: [CRYOLIST] When is a glacier no longer a glacier?

Great discussion on the difference between science and reality.

Ahemm.

>On Aug 15, 2018, at 7:49 AM, Oerlemans, J. (Hans)<J.Oerlemans at uu.nl>wrote:
>
>Dear all,
>
>Classifications are problematical by definition. That is why we invented DIFFERENTIAL EQUATIONS - to deal with a world that presents itself as a continuum.
>Classification is useful for basic teaching and communication. But let us not push it too far….
>
>Cheers !
>Hans Oerlemans
>=============
>
>
>
>>On 15Aug, 2018, at 13:10 , Francisco Navarro<francisco.navarro at upm.es>wrote:
>>
>>Dear all,
>>
>>In fact, definitions involving quantities are rarely (if ever) suitable in the natural sciences. But even when they include just concepts and no quantities. Strictly speaking, only when abstract objects or structures are defined a definition can be considered as precise. For instance, when in mathematics a boolean algebra, or a set of orthogonal functions with respect to agiven inner product, are defined. But, when natural sciences are involved, it is nearly impossible to find a precise definition encompassing all cases that we aimed to include; always exceptions or counter-examples appear.
>>
>>To put an example, thinking of glaciers, even the concept of 'motion' (showing dynamics) could be questioned in the definition. For instance, a huge mass of ice with nearly-flat surface filling, up to a certain height, the crater of a relict volcano crater would have virtually no motion (the upper surface would be a equipotential surface of the gravity field) and yet it would certainly be considered by a glacier by most people.
>>
>>Defining and classifying are inherent to human beings, and thus to science, but, as said, this effort is only 100% successful when dealing with abstract or ideal objects. And glaciers indeed are not.
>>
>>Francisco Navarro
>>
>>
>>>El 15/08/2018 a las 6:00, Jeffrey Kargel escribió:
>>>... and in addition to Alun's comments, there's the nonquantitative, ill-defined notion "we know a glacier when we see one," and its corollary, "we know it's no longer a glacier when it stops looking and behavinglike one." I just visited Wheeler Peak, Nevada (Great Basin National Park) 2 days ago, and its "glacier-like form" is the saddest case of a glacier there ever was.I see evidence of flow under the force of gravity, but it is much more like an avalanche- and rockfall-fed rock glacier. It's almost not a glacier, though.
>>>... but I can also easily be a generalist in the extreme, and say that it doesn't matter what mechanism drives the flow of a glacier.If it's a perennial icy mass flowing under force of gravity and exhibits geomorphological signs of flow, then it's a glacier.Not glacier-like, but a glacier.So then the sad case of Wheeler Peak's glacier is a glacier, even if it is also a rock glacier and a very sad rock glacier at that. I know that not many people want to lump rock glaciers with glaciers, but I see a continuum of forms, of geomorphological signs of flow, rates of flow, and of flow process ratios-- how much of each mechanism (basal sliding, internal deformation, freeze-thaw, ...) contributes to the motion; and continuum of the ice accumulation between direct snow precipitation, snow avalanches, refrozen rain; and a continuum of ice:rock ratio and rock distribution within the icy mass.So rather than get tied in knots arguing whether it is a glacier or a rock glacier, originated from an ice glacier and evolved into a rock glacier or started as talus and evolved into a rock glacier, etc.... they're all glaciers.Same idea for minimum size cutoff; I don't think there is one.But glaciers can get so small that they are not practical to map, or are so inconsequential that it's not really worth many people's concern or interest and not worth forcing anybody to have a deep concern. Then there is the further matter of where the ice comes from, where the rock comes from, how it is distributed, by what mechanisms the mass is moving, and whether it is too small to be worth your concern.If the glacier is near the margins of the definition of a glacier, for example if it takes a break from significant movement for 3 years in a row, I don't think that necessary disqualifies it as a glacier, because next year it might resume motion. But at some poorly definable point, you just say, if it walked like a duck and quacked like a duck but hasn't moved in quite a while, it's probably a dead duck. And if somebody wants to try to claim that it gave a little quack and is alive, then fine. I think the fine line between existence as a glacier and nonglacier and especially the birth and death of little glaciers is interesting, but not anything I'd fight over (or something I'd want a country like Argentina to throw somebody in jail over).
>>>--Jeff Kargel
>>>
>>>
>>>From: CRYOLIST<cryolist-bounces at lists.cryolist.org>on behalf of Alun Hubbard [abh]<abh at aber.ac.uk>
>>>Sent: Tuesday, August 14, 2018 11:55 PM
>>>To: Jiskoot, Hester; Andrew Fountain; Allen Pope
>>>Cc: cryolist
>>>Subject: Re: [CRYOLIST] When is a glacier no longer a glacier?
>>>
>>>
>>>Surely a glacier just needs to be composed (mainly) of ice&flow (under its own weight rather than by freeze-thaw or similar process that would differentiate it from a permafrost feature, rock glaciers, perennial snow patches, rock, glass even...arrghhh)….
>>>
>>>which will depend on mass balance, thickness, gradient, thermal regime, impurities, basal interface, substrate etc.but also what planet your on.(I've always been slightly bemused by the terminology of "glacier-like form" - which makes people who study glacier's on mars = glacier-like-ologists.
>>>
>>>But the point is that putting exact numbers to it is probably misguided.
>>>
>>>the rest is fluff, no?
>>>
>>>(who gives a monkeys what geologists think?)
>>>
>>>a
>>>
>>>
>>>Alun Hubbard
>>>
>>>Professor of Glaciology
>>>Dept of Geography&Earth Science
>>>Aberystwyth University
>>>WalesSY23 3DB
>>>
>>>t +44 (0)1970 622591
>>>m +44 (0)7966461004
>>>www.aber.ac.uk/greenland
>>>________________________________________
>>>From: CRYOLIST [cryolist-bounces at lists.cryolist.org] on behalf of Jiskoot, Hester [hester.jiskoot at uleth.ca]
>>>Sent: 15 August 2018 00:35
>>>To: Andrew Fountain; Allen Pope
>>>Cc: cryolist
>>>Subject: Re: [CRYOLIST] When is a glacier no longer a glacier?
>>>
>>>Dear Allen and others,
>>>
>>>When does a glacier cease to be?
>>>
>>>From Principles of Glacier Mechanics (Hooke, 2005):
>>>“As humans, one way in which we try to organize knowledge and enhance communication is by classifying objects into neat compartments, each with its own label. The natural world persistently upsets these schemes by presenting us with particular items that fit neither in one such pigeonhole nor the next, but rather have characteristics of both, for continua are the rule rather than the exception. This is as true of glaciers as it is of other natural systems.”
>>>
>>>Yet, to a glacier there may be:
>>>A minimum thickness limit: Pure ice needs to have a minimum thickness of ~30 m to deform and flow.
>>>Minimum area limits:<0.1 km2 (USGS, 2018);<0.01 km2 (Pelto, 2008);<0.005 km2 (Huss and Fischer, 2016).
>>>
>>>The book Glacier Ice (Post and LaChapelle, 1971/2000), has a beautifully written paragraph (p. 12) about when a retreating glacier ceases to be one. In summary, a glacier needs to have: True glacier ice, some ice flow, and to the geologist some specific geomorphological features.
>>>
>>>Serrano et al. (2011) is about a glacier changing into an ice patch in the Spanish Pyrenees, attempts to quantify the difference between a true glacier and an ice patch and provides some good background literature.
>>>
>>>References:
>>>Hooke, R.L. (2005). Principles of glacier mechanics. Cambridge University Press.
>>>Huss, M.,&Fischer, M. (2016). Sensitivity of very small glaciers in the Swiss Alps to future climate change. Frontiers in Earth Science, 4, 34.
>>>Pelto, M.S. (2008). Impact of climate change on North Cascade alpine glaciers, and alpine runoff. Northwest Science, 82(1), 65-75.
>>>Post, A.,&LaChapelle, E.R. (2000). Glacier ice. University of Washington Press and the IGS.
>>>Serrano, E., González‐trueba, J.J., Sanjosé, J.J.,&Del Rio, L.M. (2011). Ice patch origin, evolution and dynamics in a temperate high mountain environment: the Jou Negro, Picos de Europa (NW Spain). Geografiska Annaler: Series A, Physical Geography, 93(2), 57-70.
>>>USGS (2018) https://www.usgs.gov/faqs/there-a-size-criterion-a-glacier?qt-news_science_products=0#qt-news_science_products
>>>
>>>
>>>Cheers, Hester
>>>
>>>
>>>________________________________
>>>Dr. Hester Jiskoot
>>>Associate Professor of Physical Geography&Glaciology
>>>Department of Geography
>>>University of Lethbridge
>>>Lethbridge, Alberta, T1K 3M4, Canada
>>>
>>>phone: + 1 403 329 2739
>>>office: AWESB WE-2050
>>>email: hester.jiskoot at uleth.ca<https://webexchange.uleth.ca/owa/redir.aspx?C=c60eda09e4b14fa8a20566a5e92a73ad&URL=mailto%3ahester.jiskoot%40uleth.ca>
>>>web: http://people.uleth.ca/~hester.jiskoot
>>>
>>>Associate Chief Editor: International Glaciological Society<http://www.igsoc.org>: Journal of Glaciology<http://journals.cambridge.org/action/displayJournal?jid=JOG>
>>>Associate Editor: Journal of Geophysical Research - Earth Surface<http://agupubs.onlinelibrary.wiley.com/agu/jgr/journal/10.1002/(ISSN)2169-9011/>
>>>Fellow: Royal Canadian Geographical Society<http://www.rcgs.org>
>>>
>>>________________________________
>>>
>>>
>>>________________________________
>>>From: CRYOLIST<cryolist-bounces at lists.cryolist.org>on behalf of Andrew Fountain<andrew at pdx.edu>
>>>Sent: August 14, 2018 15:51
>>>To: Allen Pope
>>>Cc: cryolist
>>>Subject: Re: [CRYOLIST] When is a glacier no longer a glacier?
>>>
>>>I have always preferred Mark Meier's definition of a glacier. Simple, straight foward, memorable,
>>>
>>>A glacier is a mass of perennial ice or snow that moves.
>>>
>>>Andrew
>>>
>>>On Tue, Aug 14, 2018 at 2:47 PM, Allen Pope<apope00 at gmail.com<mailto:apope00 at gmail.com>>wrote:
>>>Dear Cryolist,
>>>
>>>I recently saw this documentary advertised (https://www.notokmovie.com/) about the Icelandic (former) glacier of Okjökull, and it is partly premised on being the first glacier in Iceland to lose its formal title of glacier<http://icelandmag.is/article/okjokull-glacier-loses-its-glacier-title-due-its-declining-size>. (We are going to do a screening in north Iceland, too, at the end of next week. You know, if you happen to be around Dalvík next Friday night...)
>>>
>>>This documentary uses a definition of size and thickness, and therefore not currently able to flow any more, to be stripped of its title.
>>>
>>>BUT, the Glossary of Glacier Mass Balance and Related Terms<http://unesdoc.unesco.org/images/0019/001925/192525e.pdf>defines a glacier as "A perennial mass of ice, and possibly firn and snow, originating on the land surface by the recrystallization of snow or other forms of solid precipitation and showing evidence of past or present flow. ", and it would seem that Ok, from its patterning, could be argued to show evidence of past flow, I think?
>>>
>>>So - what does Cryolist think? When does a glacier become not a glacier? Are there other examples of this being claimed/stated? Or any literature on this? I know this may seem a bit pedantic, but it is a claim that can and has clearly drive some headlines and will be happening increasingly in the future.
>>>
>>>Best,
>>>Allen
>>>--
>>>about.me/allenpope<http://about.me/allenpope>
>>>twitter.com/PopePolar<http://twitter.com/PopePolar>
>>>
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>>>
>>>
>>>--
>>>Andrew G. Fountain
>>>
>>>Department of Geology
>>>Department of Geography
>>>
>>>Address:FedEx/Shipping Address:
>>>--------------------------------------------------
>>>Department of GeologyDepartment of Geology
>>>Portland State University17 Cramer Hall
>>>Portland, OR97207-0751Portland State University
>>>USA1721 SW Broadway
>>>Portland, OR 97201
>>>Email:andrew at pdx.edu<mailto:andrew at pdx.edu>USA
>>>http://www.glaciers.pdx.edu<http://www.glaciers.pdx.edu/>
>>>Phone:503-725-3386
>>>
>>>
>>>--------------------------------------------------------------------
>>>Prifysgol Aberystwyth www.aber.ac.uk
>>>Prifysgol y Flwyddyn ar gyfer Ansawdd Dysgu - The Times&The Sunday Times 2018.
>>>
>>>Aberystwyth University www.aber.ac.uk
>>>University of the Year for Teaching Quality - The Times&The Sunday Times 2018.
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>>
>>--
>>Prof. Francisco Navarro, despacho A302-4
>>Departamento de Matemática Aplicada a las TIC
>>ETSI de Telecomunicación, Universidad Politécnica de Madrid
>>Av. Complutense, 30, 28040 Madrid, Spain
>>Tel. +34 910672279
>>e-mail
>>francisco.navarro at upm.es
>>http://www.gsnci.upm.es
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