This is an archive of past discussions about Sea level rise. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page.
What contradictions? That article (Hay, et al., "Probabilistic reanalysis of twentieth-century sea-level rise") addressed some problems in accounting for various inputs to GMSL. They got results "consistent with prior estimates from tide gauge records", but showing that the "increase in rate relative to the 1901–90 trend is accordingly larger than previously thought; this revision may affect some projections of future sea-level rise." I see no contradiction, only a refinement and confirmation of the general trend already identified. ~ J. Johnson (JJ) (talk) 22:26, 24 March 2015 (UTC)
Groundwater lowering lowers ground level in relation to sea
Latest comment: 9 years ago6 comments5 people in discussion
I'm not sure, but I believe I once heard that a lowering of the groundwater also lowers the soil itself, in relation to the sea. This would be mainly because soild with water expands, and dried out soil reduces in size.
In addition to this, water is also piped to the sea, which hence becomes a little bit higher (well, the effect of the latter is almost negligable, but perhaps still worth mentioning).
Removed from see also, do you have a reference stating the relevance here? Also, please don't change your signature after you post. Vsmith (talk) 14:42, 11 February 2015 (UTC)
Utter nonsense. The water "pumped" to the sea (mainly in the form of sewage) does not come out of no where. In most cases it is water that was taken out of a river that was flowing into the ocean anyway, and so is only a diversion of water out of the normal hydrological cycle.
Pumping of groundwater, coupled with insufficient recharge, can lead to ground subsidence; a recent article in Science described such broad subsidence in much of Californa resulting from the drought and over-pumping. You might find it instructive to calculate the volume of water involved, and compare that with the volume of water needed to raise global sealevel one inch.
However, the implication of your statement - that apparent sealevel rise might be an effect of ground subsidence - is totally off the mark. Subsidence occurs in water saturated soils, and the bulk of the eerth's crust is rock, with very little water penetration. ~ J. Johnson (JJ) (talk) 22:28, 24 March 2015 (UTC)
Most coastlines have beaches and barrier islands composed of sand and clay which are the remains of the sediments carried down from Canada by the last glaciation. Boston and Cambridge MA for example have about 90 feet of such sediments. Barrier islands composed of shells sand and coral fragments are what makes up the limestone surface rock laid down over the thin oceanic crusts farther south. In many cases the aquifer being pumped out leaves cavities in the soft rock which collapse into sinkholes and there are examples from Florida of subsidence from building loads. "Sinkholes can form gradually or -- as in the tragic case in Florida -- suddenly. They form in areas where water flowing underground has dissolved rock -- typically limestone -- below the surface, leading to the formation of underground voids into which the surface sediment falls, according to the website of the Florida Sinkhole Research Institute. They vary in size from 1 to 600 meters.Sinkholes are found all over the world. In the U.S., sinkholes are especially common in Texas, Alabama, Missouri, Kentucky, Tennessee, Pennsylvania, and Florida, according to the U.S. Geological Survey."[1]In combination with rising sea levels the subsidence results in a higher level of flooding and the more rapid abandonment of coastal communities as is the case in Alaska with the melting permafrost subsidence.142.0.102.9 (talk) 17:52, 31 March 2015 (UTC)
It seems necessary to point out that scope of the current sea level rise of this aritcle's subject is global. Every thing you just mentioned is entirely about local subsidence, which causes local flooding, and contribute nothing to global sea level rise. ~ J. Johnson (JJ) (talk) 23:14, 31 March 2015 (UTC)
This is true. It is called land subsidence. It has happened in big cities in California. There are many reports about it. Some big cities are now 15 to 20 feet lower because too much water was pumped from the ground. In some areas, levees were built to prevent the ocean from flooding the land. e.g. Alviso, California, which is near San Jose, CA. written August 11 ,2015 — Preceding unsigned comment added by 75.37.43.215 (talk) 12:54, 11 August 2015 (UTC)
Graph
Latest comment: 9 years ago4 comments3 people in discussion
Yes, here. It uses 1880–2013 instead of 1870–2008. Random question: if I were to try to fix it, would I update the current file or upload a new one and change it article-by-article? EDIT: I did the latter, and updated the article. If someone could check it, that'd be nice, since it's my first time using Wikimedia Commons. HoboMcJoe (talk) 21:42, 10 June 2015 (UTC)
Latest comment: 9 years ago3 comments3 people in discussion
As far as I can see, the article makes no mention that the annual sea level rise of ~3mm per year is only 0.1% of the typical tidal range of 3m. Thus, it would take a thousand years for the effects on sea level of postulated climate change to equal those of standard twice-daily tides. Since seawalls have to be built considerably higher than the typical tide range to accommodate spring tides and storm surges, it follows that no flooding is likely due to this very small annual rise for a very long time.
Since the surface measurements seem to originate mostly from tide gauges this also raises the question of whether the resolution of these instruments is sufficient to detect so small a percentage change. In view of the difficult nature of the measurement being made, I would be very surprised if it were that high. More likely, a few percent. However, if the accuracy is less than 0.05% -a phenomenal achievement for any mechanical gauge- then the claimed figure of ~1.7mm annual sea level rise is meaningless. (Tide data source, UK Admiralty)--Anteaus (talk) 08:25, 15 August 2015 (UTC)
As the mean level rises, the peaks rise too. In addition to that, storm surges are predicted to become more common. Also, the predictions take into account the precision of the measurements and studies usually estimate the accuracy of the results. Zerotalk09:35, 15 August 2015 (UTC)
The height of seawalls is determined 1) not by the tidal range, but of the height of the estimated storm surge over high tide, the latter being a function of mean sea level, and 2) by the parsimony of public budgets, which seem to be the minimum necessary to assure those in charge that they won't face a disaster in their lifetime. As to the accuracy of tide gauges: apparently you are not familiar with how statistics can derive "certain conclusions from uncertain data". That is, to determine a trend with a greater fineness than any single datum. ~ J. Johnson (JJ) (talk) 20:13, 20 August 2015 (UTC)
Effects of sea-level rise - Cities
Latest comment: 9 years ago22 comments3 people in discussion
It makes more sense to mention those parts which are currently affected (particularly hard hit) such as food growing regions (river deltas) or Islands, or those which have the highest projected looses in real estate, or which are most notable per secondary sources. However i wouldn't object to a list or lists. prokaryotes (talk) 20:10, 19 August 2015 (UTC)
"Currently affected" is slippery concept, especially as current sea level rise is only a portion of what is expected. (E.g.: are the lingering effects of Hurricane Sandy a current affect on New York and New Jersey?) I could see an article on current effects of sea level rise, but with a clear statement these as yet minor effects are only the beginning. As to projected effects, whether in real-estate specifically, or overall infrastructure costs, there is a 2011 article that listed twenty ports with the greatest estimated impacts by the 2070s. But any list of impacted ports (cities) seems silly: all of them will be impacted. It might be better (in the section here) to describe the the nature and magnitude of the effects, not particular places affected. ~ J. Johnson (JJ) (talk) 20:35, 20 August 2015 (UTC)
the clear statement you ask for sounds highly contentious, and you go on to refer to effects when you should refer to possible effects or projected effects. And no, if you think these "as yet minor effects are only the beginning.", then the record shows this to be untrue. Sea level has gone up & down by enormous amounts on relatively short timescales in the recent past, so you can't conceivably view recent changes in sea level as a beginning. I'm not saying that sea level won't rise a lot: I'm saying that it may rise a lot, or it may fall, and those who pretend to know are talking b@$&;(5$cks. So please flag up projections as projections and treat all the crystal ball stuff as comprising at least 50% moonshine.
SOAP, through and through. Though I will point out for your possible edification that if, say, a tree starts falling it is quite reasonable to project that it will continue to fall. And it does not take a crystal ball, only a calculator and some basic data on the volume of the West Antarctic Ice Sheet and area of the global ocean, to calculate how much loss of the former will raise the latter. However, all that is off-topic, as what we are discussing here is the effects of sea level rise. ~ J. Johnson (JJ) (talk) 22:01, 20 August 2015 (UTC)
The list has been deleted, as well as the link to it. The section needs re-writing (still looks like several factoids standing at a bus stop) but I'm feeling under-motivated. It's been a while since I looked, but I vaguely recall that one of the IPCC ARs had some material that would be useful here. ~ J. Johnson (JJ) (talk) 21:59, 28 August 2015 (UTC)
The Cities section appears to be a good brief introduction. Maybe you can give some pointers besides the IPCC and i will look into it. Will try to check that later per AR5. Thanks.prokaryotes (talk) 00:16, 29 August 2015 (UTC)
I was thinking AR5 WGII would be a good place to start looking, but a quick look there (rather painful, because it's not as well organized as AR4) showed rather woolly generality. AR4 might be better. A quick google on "sea level rise effects" showed mostly derivative stuff, not real good sources. My thinking for this section is that it could start out noting that sea level rise so far has been very modest, with modest effects. E.g., Miami sees flooding of certain city streets about ten times a year, while a year or two ago it was in the news that Norfolk VA (which is almost entirely less than 12 feet above current level) was raising a few residential streets that were starting to flood. (See here. Or even better.) It might then note that what are now exceptional events like Hurricane Sandy are worse because of the little extra boost from a slightly higher sea level, but will become the "new normal". Then it could get into the effects expected 50 years out, when very substantial sea level rise is expected. Here it would be useful to describe specific effects, such as flooding of port facilities (and related infrastructure), general flooding of low-lying cities, and even the effects on cities not directly impacted (such as loss of agricultural land, and refugees). It might mention that mitigations are often not possible (e.g., dikes won't work in Miami because the underlying limestone is porous; while Norfolk and Bangladesh are hopeless), and even where possible will be extremely expensive in a future with fewer available resources. All this affects the other subsections. I think (ha) it might be better to start with cities/ports as the most specific, then generalize to regional and island nation impacts. ~ J. Johnson (JJ) (talk) 21:34, 30 August 2015 (UTC)
Perhaps something like "even these modest effects currently cost $6 billion ...." The $1 trillion looks low: I see one forecast of $3.5 trillion by 2070 just for Miami (and also Guangzhou, China), with $2 trillion for New York-Newark. There are, indeed, plenty of good secondary sources (e.g.: the IPCC ARs, much of the NASA stuff, etc.). I think the article would be improved if we tapped those directly rather than filtered through the newspapers, which tend to have a parochial viewpoint. ~ J. Johnson (JJ) (talk) 20:54, 31 August 2015 (UTC)
Cripes, I'm getting sucked into the whirlpool. Even after your edits I think the whole "Effects" section still needs to be torn out and rewritten: it's poorly organized, it lacks focus, there is no coherent concept as to what is being communicated. I particularly question the bit about "modest increases ... are likely to be offset when cities adapt" as not quite sensible. (They are not offsetting SLR, they're only trying to cope with it.) Anyway, I'm going to run up a draft (below).
I have also just inserted a new section ("Subsidence"), between "Contributions" and "Effects", as it makes a signficant contribution to effective sea level rise and the ensuing consequences. ~ J. Johnson (JJ) (talk) 00:04, 2 September 2015 (UTC)
Draft for "Effects" section.
Actual sea level rise to-date has been modest (only xxxx inches[citation needed]), and the impacts to low-lying coastal cities have been modest. For example, in Miami (Florida) it is reported that certain streets flood at high tide about 10 times a year[citation needed], while at Norfolk (Virginia), a few residential streets have been raised.[citation needed] Yet the cost of effective sea level rise (combined with subsidence) has already (xxxx) reached an estimated xxxxx per year[citation needed], due to increased flooding from infrequent storms (as seen with Hurricane Katrina (2005), Hurricane Ike (2008), Cyclone Xynthia (2010), and Hurricane Sandy (2012)) and the cost of defense projects such as the Thames Barrier [(London) and MOSE Project (Venice). A 2011 study[1] estimated that in 2005 about 40 million people and an estimated US$3,000 billion of assets (about 5% of global GDP) were exposed to a 1 in 100 year coastal flood event.
As sea level rises (in conjunction with subsidence and storm enhancement[2] very substantial economic assets will be subjected to flooding. This will apply especially to ports (as of 2015 13 of the 20 most populous cities in the world are ports[3]), but all cities, as well as broad regions and nations, dependent on those ports will be affected. It has been estimated that by the 2070s exposed assess will exceed US$3 trillion for Miami (USA) and Guangzhou (China), over $2 trillion for New York-Newark, and over $1 trillion for eight other urban agglomerations, including Calcutta, Shanghai, Mumbai, Tokyo, Hong Kong, and New Orleans.
Please only use referenced content, for instance Miami has a new pump system, some areas flood less atm. Also i prefer storm surge, instead of storm enhancements. The draft does not mention food growing regions in river deltas, or other low lying areas. If you add something, or rewrite something, take care not to remove referenced content, unless it becomes redundant or is out dated. Also references belong at the end of a sentence. Thanks. prokaryotes (talk) 20:39, 2 September 2015 (UTC)
What do you mean by "referenced content"? As in sourced, like the points where I left "[citation needed]"? I wasn't proposing to write the whole thing myself, and I left those points to show other editors who seem closer to the particular sources where the pertinent material might go.
Nor am I proposing the draft above as the entire section. The draft arose from consideration of cities. It could be added under "Cities", or it could be augmented and made broader, and added at the top of the "Effects" section. However you wish.
I disagree that "references belong at the end of a sentence." That is a stylistic preference, which has strong disadvantage of separating citations from the specific material they support, with consequent confusion. (It doesn't help that I left out one citation, so that sentence has only two citations for three facts. Sigh.) But do it however you want, I don't really care. ~ J. Johnson (JJ) (talk) 22:13, 3 September 2015 (UTC)
I don't understand why you add above citation needed tags. Just go ahead with your edits i suggest. The only thing which bothers me so far is what i mentioned below about the S figure,and it appears that you fixed that, thanks. prokaryotes (talk) 22:27, 3 September 2015 (UTC)
I added the {cn} tags where I don't have citations for the facts (or even the facts themselves), and if the text was copied straight into the article those are the places where a {cn} would be needed. They're suggestions of where further work is needed. ~ J. Johnson (JJ) (talk) 22:45, 3 September 2015 (UTC)
Re "storm enhancement": that's the term Hanson et al. use for the general increase in extreme water levels due to more intense storms. I believe storm surge generally applies to specific cases, and reflects other factors such as tide state.
BTW: is this "new pump system" in Miami just for dealing with localized flooding? Or is there some idea that pumping is a viable option for protecting the entire area, port and all? ~ J. Johnson (JJ) (talk) 21:47, 4 September 2015 (UTC)
SE sounds very odd, but i have no strong opinion about that. Miami uses a pump system for high tide drainage. There are some local news on it, but nothing very specific, at least not what i read. There was 1 article who asked if the supposed Hurricane + high tide could flood the roads now, or not. The Hurricane dissipated. Though there are still roads which get flooded, but not those with the new multi million dollar pump system (the article mentions these adaptation affords).prokaryotes (talk) 22:03, 4 September 2015 (UTC)
I kind of wonder how the cost works out per mile of street protected. Is there talk of expanding that system, or is just a token project so the politicians can claim they're doing something? ~ J. Johnson (JJ) (talk) 22:48, 4 September 2015 (UTC)
In my opinion this seems to work for now, but the question is how long. Also stakes increase over time when pumping fails unexpected. But this is not a forum to discuss these adaptation methods, and if we delve further into it we should use related reliable sources if required. prokaryotes (talk) 06:52, 5 September 2015 (UTC)
Right. Though such considerations are not entirely out of place here, as for some (many?) people the message that (e.g.) "Miami will flood" gets diminished by the view that "no it won't, because we'll build sea-walls just like in Holland". But that does start getting away from sea-level rise itself and more towards Effects of global warming. At any rate, perhaps the draft (suitably finished out) might be useful.
I still maintain that clumping all the citations at the end of a sentence is bad practice. But in that I don't propose to change all the rest I suppose consistency will be deemed (as usual) more important than anything else. ~ J. Johnson (JJ) (talk) 21:10, 5 September 2015 (UTC)
Subsidence
Latest comment: 8 years ago8 comments3 people in discussion
Re the Subsidence section: it is not an effect of sea level rise, and its current location is therefore misleading. While it does not actually contribute to true sea level rise, it is an important contribution to local effective (or apparent) sea level rise. Which is why I put it immediately following the contributions section. (Though I don't think it would be too much of a stretch to put it at the end of "Contributions".) ~ J. Johnson (JJ) (talk) 18:26, 2 September 2015 (UTC)
It depends on how you look at it. effect of sea level rise will be different to cities or regions affected by subsidence, the cities section also mentions it. However, i have no strong opinion about this, but basically prefer to list it under Effects section (maybe rename that section?). prokaryotes (talk) 20:34, 2 September 2015 (UTC)
Like the figures on how much subsidence? Hardly arbitrary, and they are sourced. I don't think how long the subsidence has been happening (and the different contributors to subsidence are independent) matters as much as how much.
Yes, subsidence affects how much effective sea-level rise is locally observed, but it does not contribute to actual sea-level rise. Which is what the rest of the "contributors" do. To include subsidence as an effect of sea level rise (actual global, or locally observed) suggests that sea level rise is the cause of subsidence. And that simply is not true. ~ J. Johnson (JJ) (talk) 22:39, 3 September 2015 (UTC)
BTW, I think "Effects" is a better name for the section than "Implications". Consider: the anticipation of global sea level rise is implied by various measurements, but is not an effect of those measurements. The anticipation that Miami will flood is a direct consequence of sea level rise; it is an effect of such a rise. ~ J. Johnson (JJ) (talk) 22:58, 3 September 2015 (UTC)
Then move the section out there if you want. Implications is imho better since it covers relocating or flooding (which is not necessarily an effect, since it could be avoided in theory).prokaryotes (talk) 23:07, 3 September 2015 (UTC)
Okay, I moved it. And renamed it to "Subsidence and effective sea level rise" to make the the "actual SLR + subsidence -> effective SLR" relation clearer. (I was tempted to italicize "effective", but perhaps that is is not needed.) It also provides a bridge from contributions (causes) to effects.
It is unavoidable that the potential for flooding will have an effect. If not in losses due to actual flooding, then in the very expensive measures needed for mitigation. ~ J. Johnson (JJ) (talk) 21:26, 4 September 2015 (UTC)
Change in Bulge
Latest comment: 9 years ago4 comments4 people in discussion
There are many bulges observed in recent years - some have a connection to melting, feel free to improve the article with info, as long you add a reference as well. Thanks. prokaryotes (talk) 16:59, 6 September 2015 (UTC)
Latest comment: 7 years ago3 comments3 people in discussion
Could we please have some graphs in centimetres please? Most of the world has no idea what an inch actually represents, and this is an international topic on an international encyclopedia. Anyway, it's a scientific topic. Thanks for your work. 202.154.144.174 (talk) 22:18, 5 November 2015 (UTC)
Currently the article uses metres, centimetres, and millimetres. Would it be ok if we omitted centimetres, e.g. replacing 6 cm by 60 mm? Vaughan Pratt (talk) 19:22, 18 May 2017 (UTC)
"Subsidence and effective sea level rise" last paragraph quotes corrections
Latest comment: 8 years ago3 comments3 people in discussion
Hi all,
I have the source of the referenced document [75] here, and noticed the quoting of the text is not quite correct. The changes are minimal, but important enough. Lets not suggest something that was not said. The numbers quoted are the extremes in the specific area and not some sort of average or general occurrence. The original text also gives a timespan, for example for Rhine Delta. That was also missing from the quoted text.
I tried to edit the article section myself, but it seems the changes are gone now. I dont know why that is.
Here is the corrected text for anyone who likes to put it in there again (additions between * *):
"Total anthropogenic-caused subsidence in the Rhine-Meuse-Scheldt delta (Netherlands) is estimated at 3 to 4 meters *since the Middle Ages*, over nine meters in *some parts of* the Sacramento-San Joaquin River Delta, and over ten feet in *some* urban areas of the Mississippi River Delta (New Orleans).[75]"
Not sure what you mean here. The parts are quoted literally from the text but some things left out. It doesnt represent (paraphrase?) what that report is about either. We here in the Netherlands know all about subsidence and sea-levels, and we are not a sort of New-Atlantis. :) Same goes for the other areas mentioned.
My edits were reverted and as I said I don't know why. I have no account here so maybe that has something to do with it. I wont try again, but its a bit funny.
Richard — Preceding unsigned comment added by 2001:983:3BAF:1:C40F:32AE:EDEE:99A9 (talk) 17:08, 4 December 2015 (UTC)
Post-glacial rebound is larger than most predictions of Sea level Rise in Sweden and Canada
Latest comment: 6 years ago7 comments6 people in discussion
Nothing in this article mensions that the Sea level rise is more than compensated by the natural land rising by Post-glacial rebound in Northern Europe like Sweden and Canada. The Post-glacial rebound in Stockholm is 5 mm a year (5 meters in 1000 years) and some aeas in Northern Sweden it is up to 9 mm a year. This is more than most real bad predictions of sea level rise.
Also it gives much better proportions to this sea level rise article to mension that the Sea level rise is only a factor in other parts of the globe. It also gives a perspective of the natural phenomenia of changing coast lines.
--Zzalpha (talk) 08:08, 5 December 2015 (UTC)
So you are saying Swedes and Canadians can ignore this? Not likely. And you fail to note isostatic balance, so that as Scotland rebounds London sinks. Observed sea-level rise at any given location is subject to various local conditions, and it is beyond the scope of this article to address local conditions all around the globe. ~ J. Johnson (JJ) (talk) 21:44, 5 December 2015 (UTC)
The more populated areas of Sweden and Canada have much less Post-glacial rebound that the top spots, so these countries can't ignore sea level rise. In my home town Gothenburg, Sweden, new rules for house construction addresses a one meter sea level rise.--BIL (talk) 22:02, 12 May 2016 (UTC)
Zzalpa is righ IMHO to put the article in perspective. This is not about "ignoring" (whatever that may mean in a factual article..., this is not something political after all... ), it is just explaining what it is. You agreed that the "subsidence" section was useful, so why complain about the "negative" subsidence? I dont understand your reasoning.
Richard — Preceding unsigned comment added by 2001:983:3BAF:1:C9F7:BE8D:FB2E:1E1D (talk) 16:18, 7 December 2015 (UTC)
Come on, Zzalpha didn't make any specific suggestions for improving the article, he just stated a view that "Sea level rise is more than compensated by the natural land rising by Post-glacial rebound...", and that "[n]othing in this article mensions that". Unfortunately his statement is unclear, but perhaps he means that in Sweden and Canada post-glacial rebound exceeds expected SLR. (He provides no sources, but it seems plausible.) Even if, for the sake of argument, this be taken as true, so what? Does it mean, as I said before, that Swedes and Canadians can ignore SLR? (And as I also said before: not likely.) At the best it might explain ("provide perspective") why a Swede making a best-effort to measure SLR in her local fjord might not see it. But (and also as I said before) this is just a local condition, and it is beyond the scope of this article to mention all the local conditions all around the globe.
Comment Very simple, if you got a reliable source (science based) about this topic on suggested offsets, post it here, instead of just sharing your thoughts. And after a quick google there is at least one study dated from 2012, http://www.reuters.com/article/uk-environment-seas-idUSLNE8AQ01W20121127 "Up in the north where land is rising most...there won't be any problems this century," said Thomas Hammarklint of the Swedish Meteorological and Hydrological Institute, since land rise would cancel out sea rise of up to a metre." However, this is a regional effect, but could be mentioned somewhere, i.e. regional effects. prokaryotes (talk) 00:25, 12 January 2016 (UTC)
I have read that southern England is sinking and northern England is rising - rebound or tectonic? The US is rising quite rapidly in the middle and sinking on the coasts - same reason?
This will probably continue until the next ice age no matter what the temperature is.
2601:181:8301:4510:1D1D:E05C:66CC:8EE8 (talk) 12:09, 11 April 2018 (UTC)
Proposed Additions to Island Nations Section
Latest comment: 8 years ago1 comment1 person in discussion
As part of a University course at Rice University I would like to add to the Island Nations section of the Sea Level Rise wikipedia article. I will expand the given examples of island nations threatened by sea level rise with the addition of the Marshall Islands. Also, I would like to connect the scientific aspects of this section to human capabilities by analyzing how rising sea levels are affecting and changing traditional life styles. This would entail describing efforts in the Maldives, the Marshall Islands, and elsewhere to adapt to rising sea levels. I would greatly appreciate any suggestions about what should or should not be included and used for these articles. OLucier (talk) 01:52, 12 February 2016 (UTC)
Major Re-Write needed
Latest comment: 8 years ago6 comments4 people in discussion
This article is yet another causality in wikipedia's climate wars. Let's start with the very first line which is the estimate of current sea level rise. The Tidal Gauge measurements say it is much less than this article puts at the low estimate range. "Absolute global sea level rise is believed to be 1.7-1.8 millimeters/year.” http://tidesandcurrents.noaa.gov/sltrends/globalregional.htm
Next, The claim that sea level rise has accelerated in recent years is not agreed upon at all even by the IPCC which instead says that "No significant acceleration in the rate of sea level rise during the 20th century has been detected." https://www.ipcc.ch/ipccreports/tar/wg1/409.htm
Let's see, TAR would be the Third Annual Review, from 2001, and I believe the sense of that statement was that acceleration of sea-level rise (back when sea-level rise itself was not yet unambiguously detected) was also not detected yet. So what we have here is yet another yahoo who can't be bothered to consider the totality of the literature, but runs off with whatever out-of-date factoid strikes his fancy.
Yes, the article needs help. Many references are old and do not reflect current research about accelerating sea level rise. IPCC is known to have very conservative estimates: The reality is likely to be much more.Pkgx (talk) 02:47, 3 May 2016 (UTC)
Sure. But this anonymous poster has political agenda, is WP:NOT here to build the encyclopedia. And as you can see, he's still reading the Third AR. If you want to make incremental improvements (update the references, etc.), go ahead, and perhaps there will be general acceptance. But if you want to do some major revisions you would be wise to discuss it first. Which will likely be loud and contentious if any yahoos show up. ~ J. Johnson (JJ) (talk) 22:40, 3 May 2016 (UTC)
Major re-write needed. Even the most basic things that should be part of this article like the tidal gauge measurements are not here because of some political agenda. Put all of that stuff in it's own section. The global warming advocacy here is not helpful and is a major problem at wikipedia. This is an encyclopedia not a political soapbox— Preceding unsigned comment added by 24.217.75.105 (talk) 14:41, 3 May 2016 (UTC)
Still, any major revisions / re-writes need to be discussed first given the various political agendas that often become involved in discussing this topic. Also, any changes need to be supported by proper sources that are both reliable and current. Dismissing proper science as "global warming advocacy" and "man made catastrophic global warming theory stuff" using outdated sources, e.g. the 2001 TAR, only serves to contribute to the noise and confusion of the so-called "climate wars." Paul H. (talk) 15:33, 4 May 2016 (UTC)
Seawater penetration below ice
Latest comment: 8 years ago59 comments8 people in discussion
The article says that because the Aurora subglacial basin lies kilometres below sea level, "seawater could penetrate beneath the ice, causing portions of the ice sheet to collapse and float off to sea." It is true that the referenced source says this, but it seems totally illogical. The ice there is very thick, which means that the pressure at the bottom of the ice is very high – too high to allow seawater to penetrate under it. Seawater will not be able to penetrate there unless and until the ice above melts or flows away sufficiently to decrease the thickness significantly. Only then could it become a floating ice shelf and have seawater below it. Eric Kvaalen (talk) 08:26, 12 May 2016 (UTC)
Your logic is wrong. Whether water can penetrate underneath depends not on the thickness of the ice, but on whether it would float, if it were at sea, so to speak, like an iceberg. So, roughly, if the above-sea-level portion is more than 10th of the thickness, it is weighed down and wouldn't float and water can't penetrate. If less, it would float, and water can penetrate William M. Connolley (talk) 13:20, 12 May 2016 (UTC)
See the discussion at this paper. The key place to consider is the "grounding line", where rock, ice, and ocean meet. Inland of this line, the rock bears all the weight, but the ice above the line and outward on the shelf is all in shear until, somewhere, it breaks off and floats. Salt water acts to melt the ice at the line, thus moving the line shoreward. The question is, will seawater flow shoreward despite the weight of the grounded ice, or will the rate of ice advance seaward be faster than its melt back. LeadSongDogcome howl!22:07, 12 May 2016 (UTC)
@William M. Connolley: Of course what you say is true. I didn't think that was worth mentioning. The point is that the Aurora sublacial basin is way inland where the thickness of the ice is so great that no water would be able to seep under it from the sea. (It is possible that melting could occur due to geothermal heat, and then the meltwater would be squeezed out and go toward the sea! But that has nothing to do with acceleration of melting.) Eric Kvaalen (talk) 19:55, 17 May 2016 (UTC)
WMC is correct. You and the article refer to the depth of the ice or the depth of the seawater- that's inadequate.. You need to adduce extra information concerning the height of the ice above sea level at the point/linearea in question, otherwise your point fails.
Eric: it seems you do not understand that what "seems totally illogical" to you is entirely a problem of your personal understanding. What you seem to have missed is: 1) at the bottom of the ice-water contact the pressure of the water is also very high, and 2) ice floats. Well, it floats if it can sink deep enough to displace approximately the same volume of water, the latter being about 10% heavier for equal volumes. The situation you may have in mind is where the ice is resting on the bottom (more or less), so that it can't sink, and there is sufficient ice on top (above sea level) to provide more pressure than exerted by the water. Got it?
We are all happy to assist you in understanding this, but your personal confusion does not warrant tagging the section. And your repeated re-tagging, when everyone else is saying "no", amounts to edit-warring.
As it is, I think there is a problem with that source (in failing to adequately explain the matter). Which might warrant looking at the original source in Nature. ~ J. Johnson (JJ) (talk) 22:50, 24 May 2016 (UTC)
First of all, I retagged it because William reverted my edit without responding to what I had written here! Even in his latest edit comment he accuses me of edit warring, as though it were I who had abandoned the discussion. I was the last one to have written something here. Only now has there been a response from you and Gravuritas. I saw no alternative except to keep retagging it until there was more response here. After three cycles or whatever the limit is, I would have had to make a formal complaint.
Now, to address your point, I am very well aware of buoyancy and all that. The question is dubious simply because no one has done the calculation to see whether seawater pressure at that depth would be enough to float all the ice above it. If I get the time, and if I can find the elevation of the top of the ice there, I will do the calculation. Remember, to float the ice, the elevation at the top has to be less than about one tenth of the depth at the bottom! Until someone does the calculation, the statement is dubious.
The question is dubious simply because no one has done the calculation to see whether seawater pressure at that depth would be enough to float all the ice above it. If I get the time, and if I can find the elevation of the top of the ice there, I will do the calculation - that's pretty well WP:ORWilliam M. Connolley (talk) 08:07, 25 May 2016 (UTC)
@William:, is it "original research" to mark a false statement as dubious? Or to delete it? Let's assume that it really is false. How is Wikipedia supposed to protect itself from false statements that happen to appear in references? Eric Kvaalen (talk) 19:23, 25 May 2016 (UTC)
Consider: Just how do you know this statement is false? If you have to do your own research to figure it out it is, as William has noted, WP:OR. Now if you were to compare the Science Daily article with the original source in Nature, and found a contradiction, that might be different, but you haven't done that. As to making any such calculation yourself, it seems you are not competent for that. And as an editor you really are not allowed to argue with your source. I would also recommend not arguing with William, as he does have a high level of competence on these kinds of matters. ~ J. Johnson (JJ) (talk) 20:30, 25 May 2016 (UTC)
@Eric Kvaalen:: I'd suggest that such a calculation, if previously unpublished, would make a reasonable comment letter to the Nature article. If they publish it, and its correctness is accepted, e.g., by the original authors, then editors here (other than you) might have grounds to use it, e.g. not wp:OR. You assert you have an expertise in numerical methods, so it should be a straightforward undertaking. Why not go for it? LeadSongDogcome howl!20:59, 25 May 2016 (UTC)
Eric, it seems there are quite a few things here that you don't understand, including the significance of transitioning from discussion of a point you don't understand to arguing about why you're right and who said what. As to the latter I have extracted the following time-line from the article and talk page histories, with the edit summaries.
08:26, 12 May: Eric tags.
08:26, 12 May: Eric TALK: new section.
13:20, 12 May: WMC TALK: (not quite)
22:07, 12 May: LSD TALK: (consider the grounding line)
19:56, 17 May: Eric TALK: (Answer to William Connolley)
06:21, 18 May: JJ -untags: (Removed tag. Not dubious. But feel free to discuss on Talk.)
10:27, 23 May: Eric +retags: (J. Johnson, there has been discussion of this on the talk page. If you disagree, say why there (and ping me).)
12:10, 23 May: WMC -untags: (... yes, there's discussion, an I've pointed out why you're wrong)
05:11, 24 May: Eric +retags: (William Connolley, you did not explain why I was wrong. Did you read what I answered you on the talk page, as well as another person? Discuss over there, rather than just reverting.)
11:28, 24 May: WMC -untags: (... I've told you why you're wrong; and we have a RS for the text. As for reverting, take your own advice)
13:32, 24 May: Eric +retags: (William, I'm the last one to have written on the talk page. You haven't rebutted what I wrote there. "Dubious" is exactly the tag one is supposed to use when there is a source which seems to be wrong.)
16:23, 24 May: Gravituras TALK: (WMC is correct)
22:14, 24 May: JJ -untags: (... Eric, you are edit-warring. Enough. Finish the discussion before coming back.)
22:51, 24 May: JJ TALK: (Explanation for Eric)
05:33, 25 May: Eric TALK: (Reply)
08:07, 25 May: WMC TALK: (WP:OR)
Several itty-bitty details you have wrong. First, William did not "revert ... without responding". He respond to you on the 12th. I removed the tag on the 18th, you retagged on the 23rd, William removed it, you retagged on the 24th, William removed it again, you retagged (missing WP:3RR by three hours), and I removed it. Second, William did not accuse you of edit-warring, I did.
Some other points you don't understand: 1) Discussions are not resolved by whoever gets in the last word. 2) Having attracted everyone's notice with a tag, you don't get to keep adding it just because you don't like the way the discussion has gone. 3) Any interest in aiding your understanding of "seawater penetration" (or of what I think might be a real problem with the Science Daily source) is rapidly melting away in the face of your bickering. Which means you are less likely to get any discussion, but don't forget point #1. ~ J. Johnson (JJ) (talk) 20:16, 25 May 2016 (UTC)
@William M. Connolley, LeadSongDog, Gravuritas, and J. Johnson: My apologies to William. I thought it was he who was continuing to remove my tag. Other than that, I don't see what details I got wrong. (William did revert without responding, on the 23rd.)
Well, William hasn't answered my question. What about J Johnson or Gravuritas? What do you say to my question, namely IF the statement is wrong, what are we supposed to do about it?
LeadSongDog, thanks for the suggestion about writing to the journal, but that doesn't address the point I'm trying to make about Wikipedia policy.
Eric, you asked "is it "original research" to mark a false statement as dubious? Or to delete it? Let's assume that it really is false. How is Wikipedia supposed to protect itself from false statements that happen to appear in references?" There are two main ways. Either supply a contradicting source citation, or discuss on the talkpage To gain consensus. Remember that for a long time wp:V insisted on wp:NOTTRUTH. It still remains the underlying philosophy here. LeadSongDogcome howl!20:47, 26 May 2016 (UTC)
Eric: You continue to get things wrong. E.g., William responded to you on the 12th, which he referred to in his edit summary of his revert of the 23rd. As to not responding here, keep in mind that you retagged three times without any such response, so you really have no basis or justification for complaint.
As to your question: which one? Regarding seawater penetration, William has answered – your assertion to the contrary is flat-out false. (As have the rest of us, plus LeadSongDog suggested a source, which you don't seem to have checked.) If you want assistance in understanding, fine, ask, but DON'T ARGUE ABOUT IT. And most certainly don't be tagging stuff as "dubious" based solely on your own dubious understanding.
As to your "IF the statement is wrong...": I HAVE ALREADY ADDRESSED IT: "Consider: Just how do you know this statement is false?" (20:30, 25 May). You are asking how to proceed on a very dubious assumption of falsity. As an experienced editor this should not have to be explained to you. ~ J. Johnson (JJ) (talk) 21:39, 26 May 2016 (UTC)
@William M. Connolley, LeadSongDog, Gravuritas, and J. Johnson: JJ, I do not consider writing an edit summary like "... yes, there's discussion, an I've pointed out why you're wrong" to be a response! (Especially since I had already answered him on this talk page.) I don't know what you mean by saying that I retagged "without any such response". I had responded and no one had answered me.
I repeated the question: "namely IF the statement is wrong, what are we supposed to do about it?" I would still like an answer from you and William. Instead of telling me that I'm wrong, tell me what we should do if I'm right.
LeadSongDog, as I understand it, the tag "Dubious" is the thing to do, with a link to the discussion page. Once it has been discussed enough, the tag might be removed, or left.
You don't consider William's edit summary to be an adequate response? In that case, why should your edit summaries be considered adequate responses? Or is there some special rule that says your edit summaries count as discussion, but everyone else's summaries do not? The fact remains, you retagged three times without adding any discussion, so, on basic principle of equity, you have no ground for complaint.
Yet another thing you don't seem to understand is that "discussed enough" is NOT dependent on your satisfaction, but on consensus. You don't understand something? You tagged, four of us have tried to explain it to you, and though you adamantly resist understanding the matter it appears there is consensus that the question regarding the text is settled. (Distinguished from the question in your mind, which isn't really applicable here.) If you don't agree, feel free to ask for a show of hands.
Note also that there is absolutely no obligation on anyone else to explain what you "should do if [you are] right", and lack of any such explanation is no grounds for retagging. Likewise if the rest of us cease to respond to your tendentious bickering. ~ J. Johnson (JJ) (talk) 21:49, 27 May 2016 (UTC)
@J. Johnson: No, I don't consider saying "I've pointed out why you're wrong" to be an adequate response, when I had answered him. And I did not answer just with edit summaries! But we're just going in circles. I've already said these things.
I did not say that "discussed enough" depends only on my satisfaction. Certainly there was no consensus. And I have more to say, but first I would like an answer to my question, what should we do if an article says something false, with a reference. Let's say we all agree that it's false.
The traditional answer is that wiki is concerned with verifiability, not truth. A more nuanced answer is possible, and we can proceed on to that, but there's no point doing the nuances until you understand the basics. So, perhaps you'd confirm that you do understand that criterion before we move onwards William M. Connolley (talk) 14:49, 31 May 2016 (UTC)
In any case, Eric, article talkpages are not the place for metadiscussions about policy. If you feel compelled to continue that line, may I suggest you do so at wp:Village pump (policy), where it belongs? You'll be more likely to find people there who can muster up the interest in the abstract.LeadSongDogcome howl!15:08, 31 May 2016 (UTC)
@William M. Connolley, LeadSongDog, Gravuritas, and J. Johnson: The reason I am asking this question is because I would like to have your agreement that if we all see that something is wrong, then it should either be removed or marked "Dubious", even if there is a reference. The idea of "verifiability, not truth" means that things on Wikipedia must be verifiable, not just true. It does not mean that we can put things that are false just because we can find a reference that says that thing. A falsehood cannot be verified, it can only be referenced. A reference is not verification if the statement is false. I would like to move on to discussing the case in point, but I would like to know that you agree that if I convince you that the statement is false, or very likely false, we should do something about it and not just leave it as it is. Eric Kvaalen (talk) 16:01, 31 May 2016 (UTC)
No, I am not prepared to substitute my pseudonymous judgment for that of a verifiable, reliable source with a reputation for fact checking. You should not be either. More to the point, you should not expect a reader to trust such pseudonymous editors over such sources. There are reasons we developed these policies. They make sense.LeadSongDogcome howl!16:07, 31 May 2016 (UTC)
Eric, I propose an alternate agreement: That we all agree (and it appears we are four-fifths of the way there already, so all it takes is your assent) that your understanding of seawater penetration below ice is incomplete, and what you think you know is defective, that you have demonstrated no basis to support your belief of falsity, that you have ignored various explanations and suggestions, that you seem to not understand various Wikipedia principles (including WP:OR and WP:Consensus), that your hair-splitting parsing of WP:V is fallacious and unpersuasive, that you are trying to proceed on a false assumption, and that in fact you have no clue whatsoever how to proceed. With your assent to this agreement the way forward is clear and we can all get back to work on productive stuff. Okay? ~ J. Johnson (JJ) (talk) 17:30, 1 June 2016 (UTC)
@LeadSongDog and J. Johnson: Don't prejudge the outcome. I have not yet presented my argument.
So, are you saying that even if I convince you folk that the statement in the article is wrong, you will not permit even a "Dubious" tag, let alone the removal of the statement?
You haven't heard the various answers we have already provided, so why should we bother any more with you? Though let me know if you find a pig with wings. ~ J. Johnson (JJ) (talk) 21:08, 2 June 2016 (UTC)
This has absolutely nothing to do with convincing anyone of anything. It is matter of providing a WP:V and WP:RS source that supports any edit, including insertion of a dubious tag, that you make. Otherwise you are flogging a dead horse. Paul H. (talk) 01:52, 3 June 2016 (UTC)
@LeadSongDog, J. Johnson, and Paul H.: I have just rechecked the Template:Dubious documentation. We are not required to give a reliable source. In our case, a simple calculation shows that the statement in the article is wrong, using numbers from the Nature article plus elevation of the top of the ice. If we are capable of calculating whether the column of ice can be floated and we find that it cannot, then the statement is false, and the Science Daily source is shown to be unreliable. (I think you are all as capable as I of doing the calculation.) In that case we should mark it as dubious, or else just remove it. Eric Kvaalen (talk) 20:28, 3 June 2016 (UTC)
You might have a point if it was a simple ("obvious") calculation. But, AS HAS ALREADY BEEN EXPLAINED TO YOU, what you need to do to find "falsity" by your own work constitutes ORIGINAL RESEARCH. ~ J. Johnson (JJ) (talk) 20:48, 3 June 2016 (UTC)
But JJ, taking something out of an article is not the same as including original research. Neither is it original research to mark something as dubious. When one marks something as dubious, one is supposed to start a discussion on the talk page about why it's dubious (see Template:Dubious). Then people are meant to discuss whether or not it's dubious. So far there has been very little discussion about that. Originally I said it was dubious, since no one had checked whether the elevation of the top of the ice was low enough for the ice to float. Later I checked that, so now I know that it's not just dubious, it's false. I can easily convince you of that, but you and the others seem to maintain that even if we're all sure that a statement is false, we do not have the right to question it or take it out if there is a reference. It reminds me of the story of the emperor's new clothes. We all know a statement is false, but no one dares to say so. Eric Kvaalen (talk) 06:33, 5 June 2016 (UTC)
You have a WP:HEARing problem, and I am tired of it. Note that one way of quickly resolving this issue is for you restore the tag. Then someone else will revert, and we will see who can cycle the mostest and fastest. (A technique we call ROPE, but I won't trouble you with the details.) I would recommend that you not re-tag, but as you are not listening it probably doesn't matter what I or anyone else says. So suit yourself. ~ J. Johnson (JJ) (talk) 18:33, 5 June 2016 (UTC)
JJ, are you saying that even if the statement is false, and we all agree that it's false, we should still leave it in the article? Please answer yes or no. Eric Kvaalen (talk) 15:50, 6 June 2016 (UTC)
This isn't quite as outrageous as you might like us to think. Let's step through it one step at a time:
Are there false statements in reliable sources? The answer is yes, obviously, and the number is more likely to be measured in billions the millions.
Are there false statements in Wikipedia which are referenced to a reliable source?? The answer, again is yes.
What should be done if a false statement is found in Wikipedia which has a reference to a reliable source?
The short answer is it depends. The longer answer depends on the specific situation but some generalities can be discussed.
In the simplest situation, the statement is false and Wikipedia because the editor misread the reference. The solution here is simple—correct the sentence in Wikipedia.
In another simple situation the statement in Wikipedia accurately reflects the source, but the source has issued a subsequent correction. Again, the solution is simple and straightforward, after one fiuds the correction.
In a more complicated situation, one source says X and other reliable sources say Y. Wikipedia has well-established protocols for dealing with this.
Ratcheting up the complication, we might have some sources saying X and some other sources saying Y, with no clear preponderance. Again, Wikipedia has well-established protocols for how to address this.
Next, we might consider a case where there are not dueling sources, but only a single source with an obvious mathematical error. It is well-established that simple math does not constitute original research and corrections can be made. (This situation is not example of simple math.)
Now we might consider a situation restatement appears to be false, but one needs to bring in some scientific knowledge even if basic to refute the claim. In these situations, we at venturing into original research if we use that to change the claim. Presumably, if it is an important point, some other reliable source at some time will publish a contrary view, and we can move it into one of the categories discussed above where protocols exist.
Absent that, we are outside what I think are well-established protocols. We might examine how important the statement is. There are false statements that don't get corrected because they are so unimportant. If this statement is important and no one has corrected it why is that? Perhaps it hasn't been time, and we have to wait, perhaps it isn't as important as we think, or perhaps it isn't false.
With all this text I haven't suggested exactly what should be done in this specific situation, but I couldn't let the the implication that leaving a false statement in Wikipedia is absurd on its face.--S Philbrick(Talk)17:07, 6 June 2016 (UTC)
Long, but good. You didn't mention specifically the case of quoting from a secondary source that garbles the original source (which seems to be somewhat the case here), but that is resolvable (as has been previously suggested to Eric) by reference to the original source, and within the scope of what you have covered.
Eric: have you stopped beating your wife? In your own words: "Please answer yes or no." (Do you understand the nature of leading questions?) Note also that the argument you keep trying to force on us is invalid as it is based on two unproven premises. Which, in the current case, are highly unlikely. Meanwhile: is it "yes" or "no"? ~ J. Johnson (JJ) (talk) 21:08, 6 June 2016 (UTC)
Philbrick and others are perpetuating a frequent misunderstanding of WP:OR in beating Eric up. It says that WP does not publish OR. It absolutely does not say that orig research or synthesis cannot be used as an argument against NOT publishing stuff. So Eric or anybody else is free to put together anything, synthesise anything, and carry out OR to hell and back including maths of any complexity you like, in order to demonstrate that something or other currently in WP is incorrect and should not be in the article. If he is successful in demonstrating to a reasonable person that something is wrong, you have to be a complete wally to try to insist that it stays in WP until a contradictory source is found (and then only mark it dubious). Read WP:OR again and note "Wikipedia articles must not contain original research"; "all material added to articles must be attributable to a reliable, published source"; "The prohibition against original research limits the extent to which editors may present their own points of view in articles"[my emphases]
There is a difference between 1) using your own research (etc.) to argue a point with other editors (on the Talk page), and 2) relying on your own opinion to unilaterally and arbibtrarily reject a (presumably) reliable source. Note that at very top of this thread Eric said (about the questioned statement) "it seems totally illogical." Now if an expert, with many years of experience, says "hmmm, something here doesn't seem right", that would be a good sign to pause and take a look. However, Eric doesn't have that kind of expertise. He is running purely on some inner sense of dissatisfaction. He has talked of doing some kind of calculation, but it seems to me he totally fails to appreciate just what kind of calculation he would have to do in regard of the specific case of the Aurora basin. And in any event any calculation he did would not suffice to delete material, only to convince the rest of us that would be the right thing to. Which he hasn't.
What Eric is getting beat up for is not for OR, but for (seemingly) not hearing any of this stuff the rest of us are saying. ~ J. Johnson (JJ) (talk) 22:40, 7 June 2016 (UTC)
I have access to the primary source. Contact me using the link at Email Paul H.. Unfortunately, I have a publication that I need to finish ASAP and do not have the time to read through paper and prepare comments at this time. Paul H. (talk) 13:50, 7 June 2016 (UTC)
Philbrick, this is actually an important point. It has to do with how quickly the Antarctic ice cap will melt.
JJ, my question was more like "JJ, if you are beating your wife, is it against the law?" It's a hypothetical question, not a loaded question. I presume that I can easily convince you that the statement in the article is false. But I want to know whether convincing you (and the others) would make any difference. If you're going to argue that even if it's false, and we all agree, we should still leave the sentence, then why should I bother trying to convince you? So what do you say?
If you could "easily convince" us, you should have just gotten on with it. As it is, you have not convinced anyone, you are just wasting time, effort, and patience. ~ J. Johnson (JJ) (talk) 17:13, 8 June 2016 (UTC)
Is the disputed sentence only supported by the news article or also by the Nature article? I searched the Nature article for "penetrate" and didn't find anything relevant to us, but they may have used different wording --Distelfinck (talk) 17:51, 8 June 2016 (UTC)
Hey, cool, that looks like full text of the Nature article. Well, the offending statement is cited from Science Daily, and (as I have said before) I suspect it was garbled. But at this point (it being a week or two since I last looked at the article) I don't recall what the point of the sentence was. Perhaps it is time to ask whoever added that bit what they had in mind. If what Science Daily said is not supported in Nature, then the text should be removed. ~ J. Johnson (JJ) (talk) 21:55, 8 June 2016 (UTC)
@J. Johnson, Sphilbrick, Paul H., William M. Connolley, and Gravuritas: Well, JJ, if you want to be easily convinced, then here goes. The depth of the Aurora Subglacial Basin is 2426 m, but the elevation of the top surface in that area is about 2800 m. Using the density 0.917 g/cc for ice and 1.028 g/cc for seawater (from the article referenced by LeadSongDog), the seawater cannot penetrate under the ice unless the ratio of the height of ice to the depth is less than 1028/917. In fact, it's (2800+2426)/2426.
The Nature doesn't talk about this point. It's about the past, not the future. (The Science Daily reference has now been replaced by Distelfinck with another.) But what if Nature had said it? Should we really leave a statement which one can easily show to be false, and which we all agree is false, just because Nature says so?
Eric: much better. Given a doubt – no matter how it came about – you go to the the original, authoritative source (as I suggested two weeks ago). Which doesn't discuss that point? Okay, the point is not supported (and William concurs), so it may be removed. NOT because it is false (per WP:V, we are not determiners of truth), but because it is not supported by the [original] source. As to your "what if" – it didn't happen. But generally speaking: what ever is said in Nature is presumed authoritative (lacking any subsequent correction, rebuttal, etc.), while, as a Wikipedia editor, you are not. ~ J. Johnson (JJ) (talk) 23:41, 9 June 2016 (UTC)
@J. Johnson and William M. Connolley: I disagree with your idea that if it had been Nature we would have to leave it. As Gravuritas and I have said, there's no rule against using our intelligence to take something out of an article if we all agree that it's wrong. I would like to bring this debate up at the Village Pump, as LeadSongDog suggested. Now, what do you say about my putting a Dubious tag on the statement? Did I do the wrong thing?
The problem, Eric, is that you want us to assert we know better than the published authors. We have strong statements here that the grounding lines already retreat on reverse slopes, so your theoretic analysis based on gross simplifications rings hollow. The underlying fjords are neither smooth nor entirely unobstructed. They certainly are not of just one depth. We do not know how fluid the ice is at that depth and pressure, nor do we know its melting point there. If it were as simple as you think, would someone not have published an explanation for the measurements seen? LeadSongDogcome howl!20:57, 10 June 2016 (UTC)
You are defending the indefensible, and your comment above shows it. The statement originally disputed was along the lines of "because it is deep, the seawater might penetrate beneath it" which is clearly prima facie balls. The original sin of 'theoretic simplification' was in the WP article (from a source, but someone in WP repeated it in the article). You are now attempting to claim that because of obstructedness/ variation in depth / lack of smoothness/ whatever then what was prima facie bollox might actually have been true. You might be right. But the orig statement that included such an apparent non-sequitur either needed bolstering by an explanation, or it needed deleting. It's not the job of an encyclopedia to set people riddles to solve in order to understand an article.
In relation to this discussion, but not the Sea level rise article, is Evidence of a hydrological connection between the ice divide and ice sheet margin in the Aurora Subglacial Basin, East Antarctica. by A. P. Wright, D. A. Young, and many others, 2012 in the Journal of geophysican Research. vol. 117, F01033, doi:10.1029/2011JF002066. It presents solid arguments that an active hydrological system, including subglacial lakes, at the base of a warm based ice sheet filling the Aurora Subglacial Basin allows discharge from subglacial lakes near the Dome C ice divide to reach the coast. This papers provides evidence that despite the pressure of the ice sheet filling the basin, liquid water exists at its base. Although the water is flowing out to the sea, the subglacial meltwater system would provide subaqueous conduit along which melting of the ice sheet would occur with shrinkage of the ice sheet and warming of the sea water. Frankly, we are flogging a dead horse that it should be allow to rest in peace. This paper shows why I rely upon peer-reviewed papers, not anonymous editors of doubful and unknown expertise. Surely, there must be a Wikipedia procedure for ending a pointless discussion. Paul H. (talk) 02:09, 11 June 2016 (UTC)
Magnificent! I also prefer the original sources, for the same reason.
As to discussion of the original point, let's have a show of hands as to whether we done, or not.
@LeadSongDog and Paul H.:JJ seems to have gone back to saying the statement is not dubious, or that it is dubious but we don't have the right to say so! Those of us who think the statement is false do not have to prove that it is false in order for the Dubious tag to be justified. But let me address your points. First of all, LeadSongDog, the areas where we know that that grounding lines are retreating are, by definition, near the coast. As I have already said, the Aurora basin is far inland in East Antarctica, and (crucially) the elevation of the upper surface of the ice is much higher. I don't think the word "fjord" applies to the whole basin, but rather only to the parts that were sculpted by glacier movement. It is true that the depth is not constant, but in my calculation I used the maximum depth. At other points my argument is even stronger. I don't see what the "fluidity" of the ice has to do with it. We actually do know the melting point. For example, at Lake Vostok, the melting point is −3°C, at a similar pressure. But I don't see what that has to do with our question. I am not saying that there is no water down at the bottom of the Aurora basin. In fact I said that there may be water, but the "head" difference would push it toward the sea, rather than sea water flowing into the basin. Finally, I do not understand your question "If it were as simple as you think, would someone not have published an explanation for the measurements seen?" What measurements are you talking about?
Paul, the article you cite makes it clear (as you yourself say) that the flow is from the continent toward the sea, because that is the direction of the gradient of hydraulic potential ("head", to use the engineering term). I don't see why you say "despite the pressure of the ice sheet filling the basin" water exists at its base. The pressure makes it more likely for water to exist (by lowering the freezing point by 3°C) and because thicker ice means that the bottom is more insulated from the cold air above. I also don't know what you mean by "subaqueous conduit". The rate of melting is determined by the rate of geothermal heating minus the rate of conduction of heat through the ice to the surface (or convection by flowing water and ice). I don't see what that has to do with the question of whether seawater can penetrate below the ice of the Aurora Basin. And just to remind you (though I still maintain that false statements should not be put in Wikipedia), the statement in question is not from a peer-reviewed paper.
To get back to the point, there's no way that seawater can get into the Aurora Subglacial Basin, because the elevation of the upper surface of the ice is much too high. The statement in the article is false.
@User:Eric Kvaalen I'm not sure whether you've noticed, but the original sentence that you didn't like has now been deleted. @ the others: the remaining sentence in that section was still innumerate, so I have changed it.
Are we allowed to delete a referenced statement if we all agree that it is false?
Latest comment: 8 years ago4 comments3 people in discussion
Without any noticed posted here, a discussion, "Are we allowed to delete a referenced statement if we all agree that it is false?" has been opened at Wikipedia:Village pump (policy). Although I am tired of flogging this dead horse, there might be other people who might have appreciated a notification about a discussion related to this article. Paul H. (talk) 15:21, 12 June 2016 (UTC)
It does not matter. Still, you should have told someone that you did it. Many people say that they will do something and never do. Paul H. (talk) 15:33, 12 June 2016 (UTC)
Latest comment: 8 years ago7 comments3 people in discussion
The tidal gauge measurements, the most basic thing possible, say that the very first line in this article is wrong.
http://tidesandcurrents.noaa.gov/sltrends/globalregional.htm This is the official consensus source for the tidal gauge measurements and it says that their measurement is lower than your low range estimate. This needs fixing as well as everything else in the article but we will just start with the first line and go from there.
This line "Sea level rise has been estimated to be on average between +2.6 millimetres (0.10 in) and 2.9 millimetres (0.11 in) per year ± 0.4 millimetres (0.016 in) since 1993.[3]" Needs to be reconciled with the official NOAA tidal gauge measurements which says "absolute global sea level rise is believed to be 1.7-1.8 millimeters/year" At the very least this should be the low estimate of sea level rise and the higher satellite data should be the high estimate. — Preceding unsigned comment added by 97.91.188.153 (talk) 04:54, 11 September 2016 (UTC)
Moving on to sentence #2 "Additionally, sea level rise has accelerated in recent years.[4] For the period between 1870 and 2004, global average sea levels are estimated to have risen a total of 195 millimetres (7.7 in), and 1.7 millimetres (0.067 in) ± 0.3 millimetres (0.012 in) per year, with a significant acceleration of sea-level rise of 0.013 millimetres (0.00051 in) ± 0.006 millimetres (0.00024 in) per year per year."
This is also not accurate unless you include that this is minority opinion and that the IPCC and the NOAA disagree, again based on the tidal gauge measurements which did not show any significant increase and have not for about 300 years https://www.ipcc.ch/ipccreports/tar/wg1/409.htm. https://en.wikipedia.org/wiki/Sea_level_rise#/media/File:Post-Glacial_Sea_Level.png. The official scientific consensus is that "No significant acceleration in the rate of sea level rise during the 20th century has been detected." according to the IPCC and you can put your outlier study claiming otherwise after it although frankly your source doesn't seem to even support your claim and instead simply says that "Unabated global mean sea-level rise over the satellite altimeter era" which does not infact indicate an increase in the rate of sea level rise. Their claims to be measuring global sea level rise to THOUSANDTHS of a millimeter and that represents a significant increase is also fairly laughable 97.91.188.153 (talk) 15:53, 11 September 2016 (UTC)
Now to sentence #3: "According to one study of measurements available from 1950 to 2009, these measurements show an average annual rise in sea level of 1.7 millimetres (0.067 in) ± 0.3 millimetres (0.012 in) per year during this period, with satellite data showing a rise of 3.3 millimetres (0.13 in) ± 0.4 millimetres (0.016 in) per year from 1993 to 2009.[5]"
This is laughable "study". What they are doing is comparing completely different kinds of measurements and then claiming that difference shows change. There were no sat measurements in 1950, and the tidal gauge measurements which do go back to 1950 don't show an increase by 2009. This is just junk science and should be removed completely. — Preceding unsigned comment added by 97.91.188.153 (talk) 16:18, 11 September 2016 (UTC)
These look like very pertinent comments. May I ask a basic question, though? How does the NOAA, or anyone else, get from tidal gauge measurements, which presumably all reflect the relative movement of sea and land at their various locations, to an estimate of the absolute change in sea level? I would have thought that any averaging technique was subject to a matter of luck as to waht the land was doing at the various locations.
Quite contrary, to what is implied above, there are sophisticated averaging techniques that are not a "matter of luck" that can be used with great confidence to obtain consistent and reliable determinations of relative sea level changes. Such stastical techniques are discussed in detail in books such as:
Pugh, D.T., 1987, Tides, Surges and Mean Sea Level. John Wiley and Sons Ltd, Chichester, UK.
Pugh, D., and P. Woodworth, 2014, Sea-Level Science Understanding Tides, Surges, Tsunamis and Mean Sea-Level Changes. Cambridge University Press
Woodroffe, S.A. and N.L.M. Barlow, 2015, Reference water level and tidal datum. In: Shennan, I., Long, A.J. & Horton, B.P. Handbook of sea level research. Wiley, pp. 171-183.
These books also describe in great detail how useful relative sea level data is collected and will answer questions about sea level rise is calculated from tidal and other data. Paul H. (talk) 12:42, 12 September 2016 (UTC)
Thanks for the refs. May I emphasise that I was asking a question, from a non-specialist standpoint, and not intending to imply anything or assert an opinion. Sorry if my unfortunate phrasing made it look otherwise.
In addition, the tectonic component of the upward and downward movement of land can be determined by regional, even continental-scale, releveling and resurveying of established benchmarks on land and by using sophisticated models of glacial isostatic adjustment. More recently, satellite based GPS can used to directly measure onshore lateral and horizontal movement of land.
Latest comment: 7 years ago4 comments2 people in discussion
The present article, starting with the lead section, is obscure and rambling. Wikipedia:Manual of Style/Lead section says that the lead should be clear and accessible and “should identify the topic, establish context, explain why the topic is notable, and summarize the most important points, including any prominent controversies” It should say what sea level rise is and what it is not. In addition, several references are old: IPPC Fifth Assessment Report (AR5, 2013-14) is good but earlier versions are probably not. Current citations are vital.
Now for an attempt at constructive input. How about something like this for the lead paragraph?
Sea level rise refers to an increase in the volume of water in the world’s oceans, resulting in an increase in global mean sea level. Seal level rise is usually attributed to global climate change by thermal expansion of the water in the oceans and by melting of Ice sheets and glaciers on land. Melting of Ice shelfs or icebergs at sea do not raise sea levels.
Sea level rise at specific locations may be more or less than the global average. Local factors might include tectonic effects, subsidence of the land, tides, currents, storms, etc.
Sea level rise is expected to continue for centuries.[2] Because of the slow inertia, long response time for parts of the climate system, it has been estimated that we are already committed to a sea-level rise of approximately 2.3 metres (7.5 ft) for each degree Celsius of temperature rise within the next 2,000 years.[3] IPCC Summary for Policymakers, AR5, 2014, indicated that the global mean sea level rise will continue during the 21st century, very likely at a faster rate than observed from 1971 to 2010.[4] Projected rates and amounts vary. A January 2017 NOAA report suggests a range of GMSL rise of 0.3–2.5 m possible during the 21st century.[5]
There have been no improvements offered so I have placed this new wording in the lead section. As always, constructive improvement is welcome. Rlsheehan (talk) 21:30, 6 February 2017 (UTC)
Yes. I was trying hard to clean the lead section up and may have missed a couple of things. Feel free to add what you think is necessary. Rlsheehan (talk) 20:20, 8 February 2017 (UTC)
Eustatic Versus Relative Sea level Rise
Latest comment: 7 years ago1 comment1 person in discussion
It would be useful if there was an introductory paragraph that noted the distinction between "eustatic" versus "relative" sea level rise and these two types were differentiated where referred to in this article. Paul H. (talk) 03:29, 26 January 2017 (UTC)
Please delete animation from article
Latest comment: 7 years ago3 comments3 people in discussion
Personally I don't find the animation distracting, as it is quite gentle and slow moving. If you find in-page animations particularly distracting, have you looked at this webpage? It contains instructions for six ways that you can control what animations you see in your own browser. --Nigelj (talk) 14:46, 28 January 2017 (UTC)
Acceleration or No Acceleration
Latest comment: 7 years ago5 comments3 people in discussion
The article says "Sea Level Rise...has accelerated in recent years." However, Dr. Judith Curry disagrees, based upon the chart published in the IPCC AR5 report:
The key issue is whether the sea level rise during the past 50 years reflect an acceleration in sea level rise. The IPCC figure 3.14 suggests that there is no acceleration, given the large rates of sea level rise in the first half of the 20th century. Until we have an understanding of variations in decadal and multi-decadal sea level rise, we can’t make a convincing argument as to acceleration.[1]
There is no measurement that shows recent acceleration. Period. The tidal gauges are the only one that goes back very far and if you calculate them the same way all the way through they show no acceleration in the rate of sea level rise (Hence Antarctica gaining ice and the reduced rate of warming we have seen the last 20 years as opposed to the previous 20 period). There are people who claim otherwise, but they have no long term data set to prove it. It is entirely hypothetical — Preceding unsigned comment added by 2600:100A:B11D:E1C1:91FC:3AF7:F68A:D51E (talk) 21:15, 3 March 2017 (UTC)
I'm not quite sure why the IP made this comment on 5 March given that the phrase in question was removed on 6 February. In my opinion it was properly removed. While the original statement did have a source, Judith Curry is one of the most respected experts in this field. In addition arguing that it should remain because of the Earth's positive energy balance is itself OR and flawed OR. All other things being equal (which they are not) a positive energy balance supports rise not acceleration of rise.--S Philbrick(Talk)22:39, 13 May 2017 (UTC)
I should have checked the dates; I saw the template for a global map request and without thinking (or reading) assumed this thread was the new thing. At any rate, you missed and/or misconstue my points, but that doesn't really matter because the OP was not proposing any changes to the article. Are you proposing a change to the article? NewsAndEventsGuy (talk) 01:05, 14 May 2017 (UTC)
It is a 1965 report published by the White House covering some interesting aspects of many subjects and including an appendix on atmospheric carbon dioxide.
I can see value in including material based on this document. For example, the report presumably summarizes the state of climate science with respect to carbon dioxide in 1965. A number of factual statements are made. It might be useful to identify some that have stood up to the test of time and others that have not. Perhaps most have stood up well, or perhaps the last 50 years have materially improved our understanding.
The report also includes a number of projections, some for the year 2000 as well as some others. It might be useful to identify some projections where actual results have come close to projections and it might be useful to identify projections where the intervening time has demonstrated different results.
I think we might be justified in doing any of these things but that wasn't what was done in this edit. The writers of this report presumably wanted to give the readers some information about the importance of the Antarctic ice cap, and used a hypothetical scenario, assuming the ice cap would be melted in 1000 years to illustrate the impact on sea level rise. However, there is absolutely nothing in the report to suggest that the selection of 1000 years for the complete melting of the ice Is an actual projection based on solid science or even a plausible scenario. Pulling that quote out of the report and dropping it into this article leaves the impression that the scientific minds in 1965 wanted the reader to think that a sea level rise of 40 feet per century was a plausible number. While I am only speculating as to their intent, I am not speculating about the context of the report. It is most certainly not a projection — it is a hypothetical as is clearly indicated by the use of phrases such as "sometimes been suggested", "suppose that the pollward heat flux were increased", "supposing a change in the earth wide radiation balance", "if 1000 years were required".--S Philbrick(Talk)18:13, 21 May 2017 (UTC)
Yeah well, then i suggest to make it more clear that this was kind of an evaluation, and radiation balance is spot on, not so much for the assumed atmospheric mechanism of melting (in regards to Antarctica), today we know Antarctic ice sheets primarily melt from below due to warmer waters. Since this seems to be the first real kind of evaluation and sort of projection conclusion, and since it can be considered in line with some of the figures out there today, and because of the origin (Presidential), it ought to be included here. May be re-add it and make it more clear that it was basically based on assumptions. prokaryotes (talk) 18:19, 21 May 2017 (UTC)
Latest comment: 7 years ago8 comments3 people in discussion
I suggest to add projections for sea level rise from this 1981 study:
Melting of the world's ice sheets is another possible effect of CO2 warming. If they melted entirely, sea level would rise - 70 m [..] Danger of rapid sea level rise is posed by the West Antarctic ice sheet, which, unlike the land-based Greenland and East Antarctic ice sheets, is grounded below sea level, making it vulnerable to rapid disintegration and melting in case of general warming. The summer temperature in its vicinity is about -5°C. If this temperature rises ~5°C, deglaciation could be rapid, requiring a century or less and causing a sea level rise of 5 to 6 m. If the West Antarctic ice sheet melts on such a time scale, it will temporarily overwhelm any sea level change due to growth or decay of land-based ice. A sea level rise of 5 m would flood 25 percent of Louisiana and Florida, 10 percent of New Jersey, and many other lowlands throughout the world. https://pubs.giss.nasa.gov/docs/1981/1981_Hansen_ha04600x.pdfhttps://pubs.giss.nasa.gov/abs/ha04600x.html
General comments. W're not a WP:QUOTEFARM and I'm generally opposed to stringing long quotes together like stringing beads. We need to write our own text to tell a cohesive and concise story about the article's topic, and we cite sources to provide verification. If you think this RS can help us do that, please explain how it fits in with the rest.NewsAndEventsGuy (talk) 11:57, 22 May 2017 (UTC)
This quote is the related content from that study, for the article i suggest to add 1-2 sentences, under the section for 20th century projections. The point being, scientists were well aware in the 20th century already, and made calculations, and projections into the future, including quantitative estimates. prokaryotes (talk) 13:24, 22 May 2017 (UTC)
As a semantic point, when I see the Section "Projections" followed by subsections "20th century", "21st century", and "After 2100", it seemed obvious that these were projections about those periods. Consistent with that assumption, the discussion in "after 2100" is a discussion about what happens after 2100. Similarly, the entries in "21st century" are predominated by predictions about the 21st century. However, the subsection "20th century" is not a prediction about the 20th century but a prediction about the 21st century made in the 20th century. We are mixing apples and oranges.--S Philbrick(Talk)15:03, 23 May 2017 (UTC)
The word "predicted" in the recent addition:
Hansen et al 1981, published the study Climate impact of increasing atmospheric carbon dioxide, and predicted that anthropogenic carbon dioxide warming and its potential effects on climate in the 21st century could cause a sea level rise of 5 to 6 m, from melting of the West Antarctic ice-sheet alone. (emphasis added)
is too strong. Confusingly, Hansen uses the term prediction on occasion, but in context it is clear he is talking about predictions based upon scenarios, which might better be called projections or perhaps scenario-based projections. For example he specifically says "prediction of the climate effect of CO2 requires projections of the amount of atmospheric CO2…". Note he further goes on to identify variables that are specifically neglected which is perfectly acceptable in a scenario-based projection but cannot possibly be called a prediction.--S Philbrick(Talk)15:28, 23 May 2017 (UTC)
We also have to be careful about cherry picking. The very same article includes the statement:
...It is not certain whether CO2 warming will cause the ice sheets to shrink or grow. For example, if the ice warms but the air above the ice sheets remains below freezing, the effect could be increased snowfall, net ice sheet growth, and thus lowering of sea level".
In an article about sea level rise, why would we choose one scenario in which the sea level rise is significant and ignore the one in which the sea level rise is negative? While the author goes on to suggest that the West Antarctic ice sheet melting could overwhelm the effects generating a sea level decrease, that conclusion is contingent, if the West Antarctic ice sheet melts on such a timescale....
The author has made sure to cover himself — if the sea level rises in the 21st century he can point to his article "predicting" it, if the sea level drops in the 21st century can point to the same article "predicting" it. One option is to report this honestly and note that he mentions both projections, another possibility is that this isn't the best source to be summarizing.--S Philbrick(Talk)15:39, 23 May 2017 (UTC)
External links modified
Latest comment: 7 years ago1 comment1 person in discussion
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Latest comment: 7 years ago2 comments2 people in discussion
...erosion, sedimentation and the accumulation of sediment in rivers, oceans and other bodies of water. That sedimentation eventually causes all "reservoirs" to become full of sediment displacing all the water. Its a known issue in almost ever man-made reservoir ever created. It also causes water depths to be reduced, increases sunlight heating of water and drives up water temperatures throughout the reservoir. It can't be ignored and its evident every time a port or river channel has to be dredged to keep it navigable. Yet there's absolutely no mention of it whatsoever as even a POSSIBLE cause or contributing factor in "sea level rise". But "subsidence" is, even though increasing sediment volume and depth in coastal and delta regions should offset the supposed "settling" of coastal areas into the bodies of water they border.
Where "subsidence" is a concern, its primarily due to dewatering of the soil when wells are drilled to provide drinking water or to lower water tables so basements and foundations don't flood. Of course it goes without saying that when you take water out of the soil, it dries, contracts and becomes compressed. Buildings and other structures don't or at least shouldn't sink when they're large and heavy enough to be heavier and more dense than the soil supporting them because they should have foundations built on pilings driven down to "bedrock". But that hasn't occurred in many major coastal cities with rapid development and lots of land created by "fill" And even "bedrock" can sink if it's supporting enough weight. Especially if IT'S dewatered and dries out and contracts.
Regardless, sedimentation USED TO BE AN IMPORTANT PART OF EARTH SCIENCES AS TAUGHT IN ANY U.S. ELEMENTARY SCHOOL SCIENCE CLASS. Which is understandable because it so obviously exists, its so visible and so easily understood. And how old is the "average person" when he or she discovers that throwing solid objects in a container of liquid pushes the "level" of the fluid up inside the container? But supposed "scientists" and Wikipedians allegedly interested in and devoted to "science" AND "building an encyclopedia" have never heard of it or are completely ignoring it?
There's no mention of it because it has no global systemic effect on sea level. You seem to forget that Earth's plate tectonics are constantly recycling crust from ocean depths into islands and continents via subduction zones, volcanoes, rift valleys and mid-ocean ridges. Erosion and deposition can have small-scale (on a global basis) effects in a short time frame, but the amount of continental crust on the planet changes in time scales of millions and billions of years — not a century or two. NorthBySouthBaranof (talk) 08:01, 18 July 2017 (UTC)
Your satellite graph is out of date.
Latest comment: 7 years ago1 comment1 person in discussion
It provides a misleading view of the most recent data. See the latest NASA graph here for years after 2014:
https://climate.nasa.gov/vital-signs/sea-level/ — Preceding unsigned comment added by [[User:{{{1}}}|{{{1}}}]] ([[User talk:{{{1}}}#top|talk]] • [[Special:Contributions/{{{1}}}|contribs]])
