tag:blogger.com,1999:blog-8524070301101240472.post6688001989787464978..comments2023-09-28T08:13:11.489-07:00Comments on Only In It For The Gold: Melting Ohio DailyMichael Tobishttp://www.blogger.com/profile/08229460438349093944noreply@blogger.comBlogger20125tag:blogger.com,1999:blog-8524070301101240472.post-64581881463254438422009-11-21T05:11:54.417-08:002009-11-21T05:11:54.417-08:00Thank you for the good post, and the prompting to ...Thank you for the good post, and the prompting to go back and read AR$ again. If you read the details of AR4 on glaciers and ice sheets it reads pretty well. However, there are some odd statements.."Until recently (including IPCC,2001), it was assumed that velocities of these outlet glaciers and ice streams cannot change rapidly, and impacts of climate change were estimated primarily as changes in snowfall and surface melting. Recent observations show that outlet glacier and ice stream speeds can change rapidly, for reasons that are still under investigation. Consequently, this assessment will not adequately quantify such effects." <br />Attending a meeting on Fast Glacier flow in 1986 the focus was on this topic how fast changes in the flow in some of the ice streams had occurred. Working on Pine Island Glacier and Jakobshavn at the time with T.Hughes of U Maine, we were trying to model how to apply the Jakobshavn model to other glaciers. The problem was accurate data on the thickness and bottom profile of the glaciers. The community did realize that some ice streams had turned on and off so to speak. So here we are 20 years later and I read an assumption that was viewed as not true in the mid-1980's. ice streams do respond fast, that was why we were studying them, we were trying to learn how, since there was more than one mechanism. Alley was there as a doctoral, focussed. on the speed of Antarctic Ice Stream B- now Whillans Ice Stream- Whillans was there too. The other odd statement is .."Enhanced flow in ice streams arises either from higher gravitational stress linked to thicker ice in bedrock troughs, or from increased basal lubrication." Since it is has been well documented that it is the thinning in the lower reaches of the calving tidewater glaciers resulting in reduced frictional stresses that leads to the acceleration. The gravitational stresses are not as important. This again was a point that has been recognized for some time. However, was lost by some, which led to the over emphasis of the silly notion that moulins were the key to GIS acceleration. <br /><a href="http://www.realclimate.org/index.php/archives/2008/04/moulins-calving-fronts-and-greenland-outlet-glacier-acceleration/#more-550" rel="nofollow"> RC article</a><br />We have all been surprised not that this can happen, but that it is on so many ice stream and glaciers. I know that when I selected some of the glaciers I did to work in, I expected them to disappear, just not so fast. <a href="http://glacierchange.wordpress.com/2009/07/19/milk-lake-glacier-loss/" rel="nofollow"> Milk Lake Glacier </a>ThanksJillhttps://www.blogger.com/profile/06580691104782729492noreply@blogger.comtag:blogger.com,1999:blog-8524070301101240472.post-73264749311754875472009-11-20T12:02:58.788-08:002009-11-20T12:02:58.788-08:00Thanks to Dr Pelto for reading and commenting.
I ...Thanks to Dr Pelto for reading and commenting.<br /><br />I would point out that this is another instance of the difference between "what is known" in the three major senses: 1) what somebody knows 2) what the field accepts and 3) what the public believes. (Many additional finer variants can easily be constructed, but these are the main classes.)<br /><br />I was aware of the theory that the WAIS might collapse early in my student career around 1994. I would not go so far as to say I believed it, deferring to the common wisdom within the climatological field (as opposed to the glaciological subfield). <br /><br />Even AR4 was unwilling to take a position on how ice sheets behave under warming, though by then I had some exposure to glaciology which turned out vastly more interesting than I had suspected, as many things do. So my expertise climbed a little and the acceptance of the idea spread a little, so now I take it as "known".<br /><br />It's a very interesting question in the face of new developments in "agnotology": the science of cultivation of popular ignorance. The gap between class 2 and class 3 of "what is known" has drastically widened.Michael Tobishttps://www.blogger.com/profile/08229460438349093944noreply@blogger.comtag:blogger.com,1999:blog-8524070301101240472.post-17615289933893434162009-11-20T11:36:55.414-08:002009-11-20T11:36:55.414-08:00Sure, Mauri, but look at the AR4. Jim Hansen wasn...Sure, Mauri, but look at the AR4. Jim Hansen wasn't calling Richard Alley and others reticent for nothing. Speaking of Richard, he continues to push back on this stuff, e.g. at the Oregon PAGES conference when he mischaracterized as a prediction Jim's remark about multi-meter SLR being more likely than the AR4 number. As Richard continues to be seen as the most prominent voice among U.S. glaciologists, it seems to me that he needs to get some squawks when he does stuff like that. Otherwise the entire field will be seen as in agreement.Steve Bloomhttps://www.blogger.com/profile/12943109973917998380noreply@blogger.comtag:blogger.com,1999:blog-8524070301101240472.post-90134288387364227812009-11-20T09:53:01.694-08:002009-11-20T09:53:01.694-08:00My great-grandfather worked for Humble Oil in the ...My great-grandfather worked for Humble Oil in the Texas Panhandle...waghttps://www.blogger.com/profile/07220188306371171380noreply@blogger.comtag:blogger.com,1999:blog-8524070301101240472.post-61629362634780470272009-11-20T05:24:38.865-08:002009-11-20T05:24:38.865-08:00I will disagree with your interpretation of what w...I will disagree with your interpretation of what we knew about ice sheets 15 years ago. Twenty five years ago I spent a lot of time modelling ice sheets and it was the calving losses and changes in bed conditions that were the key. We have know this is the weakness and the problem of the WAIS for sometime just as an example look at the history of the idea of the Pine Island Glacier as a weak underbelly, <a href="http://www.realclimate.org/index.php/archives/2009/11/is-pine-island-glacier-the-weak-underbelly-of-the-west-antarctic-ice-sheet/" rel="nofollow">Realclimate review </a> a term I knew 25 years ago.Jillhttps://www.blogger.com/profile/06580691104782729492noreply@blogger.comtag:blogger.com,1999:blog-8524070301101240472.post-7674589155935796262009-11-19T16:12:23.606-08:002009-11-19T16:12:23.606-08:00Oh, I dunno. I could envisage an article written,...Oh, I dunno. I could envisage an article written, say 5 years from now... on the subject of denialism that might describe what message Enco was going for...even back then. A modern picture next to this - is or will be showing a scene greatly diminished. <br /><br />http://www.theboywhodeniedwolf.com/2009/04/google-timeline-reveals-triumph-of-denialism.html<br /><br />http://news.google.com/newspapers?id=xQAOAAAAIBAJ&sjid=_HsDAAAAIBAJ&pg=7244,4365891&dq=global+warmingrpaulihttps://www.blogger.com/profile/00016149709193595632noreply@blogger.comtag:blogger.com,1999:blog-8524070301101240472.post-91619588997418153792009-11-19T14:47:35.278-08:002009-11-19T14:47:35.278-08:00What a strange question!What a strange question!Michael Tobishttps://www.blogger.com/profile/08229460438349093944noreply@blogger.comtag:blogger.com,1999:blog-8524070301101240472.post-5265589432681885962009-11-19T14:42:25.665-08:002009-11-19T14:42:25.665-08:00Where is the modern photograph of the same scene?Where is the modern photograph of the same scene?rpaulihttps://www.blogger.com/profile/00016149709193595632noreply@blogger.comtag:blogger.com,1999:blog-8524070301101240472.post-45244358786597220822009-11-19T10:52:44.889-08:002009-11-19T10:52:44.889-08:00This comment has been removed by the author.Michael Tobishttps://www.blogger.com/profile/08229460438349093944noreply@blogger.comtag:blogger.com,1999:blog-8524070301101240472.post-13755645593208171502009-11-19T09:59:37.704-08:002009-11-19T09:59:37.704-08:00Hank,
Looks like a rock not an iceburg.Hank,<br /> Looks like a rock not an iceburg.Nosmohttps://www.blogger.com/profile/18276735115398361316noreply@blogger.comtag:blogger.com,1999:blog-8524070301101240472.post-58771573646475707332009-11-19T07:46:15.767-08:002009-11-19T07:46:15.767-08:00Rust, not sure what you are saying. The 7e6 is Hum...Rust, not sure what you are saying. The 7e6 is Humble's 1962 number, not a physical constant.Michael Tobishttps://www.blogger.com/profile/08229460438349093944noreply@blogger.comtag:blogger.com,1999:blog-8524070301101240472.post-65126913730637175332009-11-19T07:31:52.976-08:002009-11-19T07:31:52.976-08:00Now here's an optimistic take.
Maybe the icebe...Now here's an optimistic take.<br />Maybe the iceberg will melt before we hit it ...<br />http://www.seattlepi.com/dayart/20091118/cartoon20091118.jpgHank Robertshttps://www.blogger.com/profile/07521410755553979665noreply@blogger.comtag:blogger.com,1999:blog-8524070301101240472.post-16611584250961458452009-11-19T07:19:56.274-08:002009-11-19T07:19:56.274-08:00Nice bit.
One minor nit, which also does not &quo...Nice bit.<br /><br />One minor nit, which also does not "cascade". Following your calculations to paragraph 5, I get one barrel of oil "melts" ~ 18 tons of ice, not 3 tons? I.e. 7*10^6 / 3.9*10^5 ? Did I miss a step?Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-8524070301101240472.post-77030083395996860542009-11-18T23:42:10.836-08:002009-11-18T23:42:10.836-08:00" could melt an area of meter-thick ice cover..." could melt an area of meter-thick ice covering a mid-sized state."<br /><br />To use UK standard measurements, that's about 14 times the area of Wales (880 square miles), to the depth of a double decker bus (4.38m).skankyhttps://www.blogger.com/profile/14584908320777937193noreply@blogger.comtag:blogger.com,1999:blog-8524070301101240472.post-43962220848052488692009-11-18T21:28:05.152-08:002009-11-18T21:28:05.152-08:00Corrected. Fortunately the error does not cascade....Corrected. Fortunately the error does not cascade.<br /><br />I appreciate people checking up on this. Part of the point of this sort of exercise is getting people to play along. <br /><br />Anyway my fallibility is part of my charm...Michael Tobishttps://www.blogger.com/profile/08229460438349093944noreply@blogger.comtag:blogger.com,1999:blog-8524070301101240472.post-64868890371944120642009-11-18T21:22:09.403-08:002009-11-18T21:22:09.403-08:00Thanks and aargh.Thanks and aargh.Michael Tobishttps://www.blogger.com/profile/08229460438349093944noreply@blogger.comtag:blogger.com,1999:blog-8524070301101240472.post-75633710176762320092009-11-18T21:11:50.130-08:002009-11-18T21:11:50.130-08:00Sigh. I feel bad about this nitpicking but an Amer...Sigh. I feel bad about this nitpicking but an American football field is 120 yards by 160 feet. See <a href="http://en.wikipedia.org/wiki/American_football_field#Field_and_players" rel="nofollow">here</a> (by the way, WoframAlpha gives the useless answer of "100 yards" when queried about this). This actually does make a difference to your calculations, though not an order of magnitude.King of the Roadhttps://www.blogger.com/profile/06841601144107400103noreply@blogger.comtag:blogger.com,1999:blog-8524070301101240472.post-50400630470272240082009-11-18T20:51:02.749-08:002009-11-18T20:51:02.749-08:00I tried hard to resist, but failed. A ton for Enco...I tried hard to resist, but failed. A ton for Enco in 1962 would surely have been a short ton, or about 907 kilograms. Clearly it doesn't defeat your point.<br /><br />Also, it's a bit of a shame you used Wikipedia for your latent heat source, you have found something which WolframAlpha could actually have supplied, a feat of which I'm rarely capable.King of the Roadhttps://www.blogger.com/profile/06841601144107400103noreply@blogger.comtag:blogger.com,1999:blog-8524070301101240472.post-29759196052547853752009-11-18T20:31:34.850-08:002009-11-18T20:31:34.850-08:00Not silly at all. That is pretty much what we thou...Not silly at all. That is pretty much what we thought about the ice sheets about 15 years ago. <br /><br />It turns out it's wrong, though. That's not how ice sheets fail.<br /><br />They fail mechanically. As they warm, they crack and slip, and eventually fall into the ocean. The good news (sort of) is that this cools the ocean a bit. The bad news is that the ocean gets a little bit bigger...<br /><br />There's paleclimate evidence at 14Ka of a big chunk of Antarctica falling off in the space of a century or so.<br /><br />The West Antarctic looks poised to fall into the ocean first. The main part of Antarctica looks safe.Michael Tobishttps://www.blogger.com/profile/08229460438349093944noreply@blogger.comtag:blogger.com,1999:blog-8524070301101240472.post-89556639625722392812009-11-18T19:57:07.055-08:002009-11-18T19:57:07.055-08:00From MT's post, world's daily oil producti...From MT's post, world's daily oil production produces CO2 that traps enough heat to melt 55,000 square miles of ice of a depth of a meter = 142 km^3.<br /><br />Admittedly, these are kind of silly calculations, but...<br /><br />http://www.ipcc.ch/ipccreports/tar/wg1/412.htm#tab113<br />Total ice volume in the world's glaciers is 80,000 km^3.<br /><br />That's 56 days.<br /><br />Total ice volume on the planet - 28.56 * 10^6 km^3.<br /><br />That's 550 years, so that's good. If we weren't fiddling with the earth's albedo and melting the permafrost, I'd be less concerned about Greenland and Antarctica. <br /><br />(Again, I recognize this is a silly way of going about it.)The Cunctatorhttps://www.blogger.com/profile/00011732580647430145noreply@blogger.com