Talk:Sea level rise

A summary of this article should be added to sea level.

Sea Level Rise and Altitude Measurements

Nothing in the article currently about the effects of sea level changing with regards to measuring altitude - something that people reading this article may be interested in. Does anybody have any information on if the sea level rising would change the altitude measurements of cities and/or mountains? ie would a 100mm rise in sea-level result in Mt Everest being 'officially' 10cm shorter than before the sea-level rise? Or is that a fixed point only refered to as sea level? 91.164.142.53 11:26, 8 May 2007 (UTC)

Old talk

The previous first paragraph was misleading; Global Warming is one of the ways in which sea level can rise. SIDE NOTE: Even though the major causes of Global Warming and sea level rise can still be debated, it is a measured fact that these phenomenon have, and are currently occuring. maveric149

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From old ToDo subpage:

Need to add the following info:

1. Current IPCC data
2. Introductory mention of increases and decrseases in sea level in geologic history (Trans/re-gressions)
3. Those areas that are the most vulnerable (Islands, S. Florida, Bangladesh etc.)
4. Drowning of estuaries/mashes which will be blocked from migrating inland because of human settlement.

See also : Sea level rise

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I don't think the first paragraph should assert that sea level rise is caused by global warming. Let's postpone discussion of causes till the second or third paragraph.

I suggest we first define sea level rise, then discuss its consequences (such as coastal flooding and island evacuation) and talk about causes for the remainder of the article. --Uncle Ed 18:05 Feb 7, 2003 (UTC)

The intro para should be fairly self-contained. Therefore some mention of causes should be presented. But after the intro para the scheme you propose looks good. --mav 20:18 Feb 7, 2003 (UTC)

I want to make very sure I understand you, Mav, because I respect you above almost anyone else on Wikipedia (you da man!). Are you saying we should take out the "caused by global warming" thing from the first paragraph, as I suggest? Something like:

Sea levels have been rising slowly but steadily for centuries, causing coastal areas to be flooded and even some island atolls to disappear. The average rise is X mm/year, for a total rise of Y from 18XX to 19XX.

The effects on coastal communities has been blah blah blah. The following islands have been entirely evacuated: A, B, C, ...

Causes of the rise include...

--Uncle Ed

No not really. All I am saying is that the intro should also serve as a summary of the major points in the article. Global warming as a cause of sea level rise, is such a major point. This article also needs to be general in a geologic sense: Far greater rises in sea level have occurred in the geologic past (if I remember correctly, the last great rise in sea level happened 24 million years ago. The leading theory for that, was a sudden and large increase in atmospheric CO2 levels possibly from methane hydrates). What we really should be doing is describing the various phenomenon that cause changes in sea level. Focussing on only sea level rise misses the big picture of climate change (global warming is in the same boat). Some factors besides CO2 that effect sea level: Isotasy (esp. the rebound of continents after the weight burden of continental glaciers has been removed), differences in the geomorphology of the ocean basins (esp. the presence or absence of deep trenches), the amount of sediment coming from continents and being deposited on the ocean floor, etc. I really think all this should be in a general sea level article. The detail can and should then be spun-off as soon as that article got too long. --mav 21:43 Feb 7, 2003 (UTC)

(William M. Connolley 18:58, 2 Sep 2004 (UTC)) I have now added a piccy to act as overall summary; and a brief summary too. Data from IPCC TAR.

Effect of ice shelves?

OSO added:

Ice Shelves float on the surface of the sea and, if they melt, should actually decrease sea levels. This can be inferred by ice cubes floating in a glass of water which, when they melt, result in a decrease in water level. It can be argued, however, that if ice shelves melt, that it is a precursor to the melting of ice sheets on Greenland and Antarctica.

Ice cubes melting in a glass of water do not decrease the overall water level. The floating ice displaces water equal to the mass of the ice (and because it is the same substance it displaces a volume equal to its melted volume). Once the ice has melted into water, it continues to displace water equal to its melted volume - because that is what it now is. The level remains exactly the same (try it). However, floating fresh water ice cubes in glass of sea water causes the ice to ride higher in the glass because with the sea water being denser, the ice displaces its own mass by displacing less of the sea water. Thus when the ice melts, the level of the liquid in the glass rises.

However this (and indeed the whole article) overlooks a little known but well understood effect. The level of the salt water in the glass may rise. But if the experiment was repeated by floating a single ice cube on a tank the size of 100 Olympic sized swimming pools of sea water and, assuming it was possible to measure the liquid level change as the ice melted, it would be discovered that the level would actually fall very slightly.

This results from the mixing of 2 disimilar liquids occupying less volume than the original liquids. The fall in level in this case is very small because the liquids are not that disimilar, but there are disimilar liquids that occupy considerably less volume when mixed than the originals. (I wish I could remember the two liquids where this was so dramatically demonstrated at school - the combined liquid was around two thirds of the two originals).

Not sure why they are supposed to decrease sea level. According to http://www.radix.net/~bobg/faqs/sea.level.faq.html (using sea ice, but its the same) they would marginally raise sea level.

This probably needs to be placed into the article. The web link above states that ice shelves will have no significant impact either way. I have yet to be convinced but the fact is that when they melt the sea levels will not rise at all. One Salient Oversight 10:55, 12 Oct 2004 (UTC)

(William M. Connolley 11:16, 12 Oct 2004 (UTC)) Read the bit in the FAQ about the small effect of sea ice melting - this applies to ice shelves too. Why do you now say that "the fact is that when they melt the sea levels will not rise at all" when you put the bit about sea level falling into the article? Ditto the bit about ice cubes - where does that come from?

I suppose I'm trying to be logical here. Take a glass of water and place an ice cube in it. What happens? The water level rises because it has been displaced by the ice. But when the ice melts the water level drops. My argument is that the same thing happens with ice shelves. They float on the water and their increased bulk displaces it. If they melt then the displacement stops and water levels drop.

If both the water and the ice are fresh water, then the water level does not drop - it remains exactly the same.

(William M. Connolley 13:12, 12 Oct 2004 (UTC)) Not sure of your logic. Or rather, I'm sure your logic is wrong. Sorry. I've edited then re-organised the page somewhat.

Ice sheets are a different matter. They exist on land (Greenland and Antarctica). If they melt then the water will run into the sea and sea levels will rise.

It may be that the salt water / fresh water difference may cause something other than what I'm arguing here. I'm happy to be proved wrong if you can explain it all to me.

One Salient Oversight 12:26, 12 Oct 2004 (UTC)

For that last point, see the FAQ:

First, why can't the other four be catastrophic? Sea ice cannot change sea level much. That it can do so at all is because sea ice is not made of quite the same material as the ocean. Sea ice is much fresher than sea water (5 parts per thousand instead of about 35). When the ice melts (pretend for the moment that it does so instantly and retains its shape), the resultant melt water is still slightly less dense than the original sea water. So the meltwater still 'stands' a little higher than the local sea level. The amount of extra height depends on the salinity difference between ice and ocean, and corresponds to about 2% of the thickness of the original ice floe. For 30 million square kilometers of ice (global maximum extent) and average thickness of 2 meters (the Arctic ice is about 3 meters, the Antarctic is about 1), the corresponding change in global sea level would be 2 (meters) * 0.02 (salinity effect) * 0.10 (fraction of ocean covered by ice), or 4 mm. Not a large figure, but not zero either.

And I'm about to go to bed. Before I do I intend to begin the experiment outlined here that argues that there is no net difference in melting ice cubes. Another interesting site that uses ice cubes as an example is http://www.flem-ath.com/worry1.htm

One Salient Oversight 12:40, 12 Oct 2004 (UTC)

I stand convinced. The experiment proved me wrong. Thanks also for moving and changing my text to be more accurate. One Salient Oversight 22:49, 12 Oct 2004 (UTC)

(William M. Connolley 08:19, 13 Oct 2004 (UTC)) OK :-)

21 Nov 2004 (sidd@membrane.com): I have added a small section on the TOPEX/JASON satellite data.

7 Dec 2004 (sidd@membrane.com): Added references to subpolar, Greenland and Alaska glacier contribution.

7 Mar 2005 (sidd@membrane.com): Sec 5: Added references to Rignot et al.(2002,2004) and Thomas et al. (2004) re Greenland and West Antarctic contributions.

Merged with Sea level change

(William M. Connolley 22:40, 12 Jan 2005 (UTC)) I have merged in text from sea level change. The biggest bit is the sedimentary section, which is quite chatty. I'm not very good at sedimentary stuff so have mostly left it.

I am disturbed that the entry Sea Level Change has been redirected here. I object that people interesting in understanding what causes change (*fall* as well as rise) get directed to an entry that stresses *rise* (and then gets into stuff that properly belongs under "Climate Change"...note I didn't say global *warming*). NPOV, folks, NPOV. Let's change this entry's name to Sea Level Change and redirect sea level rise to this page.

(William M. Connolley 21:55, 26 Mar 2005 (UTC)) Please sign your comments (four tildas). SLR seems better - its much of the text, and its what most people are interested in.

I would support the creation of two pages, "sea level change" that deals primarily with the long term variations relavant to geology and evolution, and a second page at perhaps "recent sea level rise" that deals with the last 20 kyr or so and incorporates virtually all of the material on this current page. Dragons flight 22:34, Mar 26, 2005 (UTC)

Morner

(William M. Connolley 21:39, 8 Feb 2005 (UTC)) I've removed the Morner stuff SEW added. Sorry. Because: Morner represents no-one but himself. There *is* no INQUA commission with that name. Morner has been told to take that website down and to stop misrepresenting himself [1].

Correction. If you read that document a bit more carefully, you'll see that there is not CURRENTLY an INQUA commission with that name, and he is not CURRENTLY its president, but there was, and he was, up until July 2003 when the INQUA disbanded the commission. I don't think that warrants complete removal of his prediction. — Cortonin | Talk 22:20, 8 Feb 2005 (UTC)

(William M. Connolley 22:29, 8 Feb 2005 (UTC)) Yes it does, because the site itself is now invalid, since it misrepresents itself.

If you had read the site, you would see it was from 2000, which was well before the disbanding of that commission. There is no misrepresentation going on. Please stop removing his estimates from the article. If you have the IPCC predictions, it's perfectly legitimate to include a primary opposing view to the IPCC predictions. That's how Wikipedia achieves NPOV. — Cortonin | Talk 22:39, 8 Feb 2005 (UTC)

(William M. Connolley 16:47, 9 Feb 2005 (UTC)) The site claims the current existence of the comission, by implication. It is therefore deceptive, and deliberately so. The "estimates" by Morner have no status at all, and should not be referenced. If you can find them in a published journal then fine - add them and source them properly. But picking stuff off dodgy web pages is no good. I see you found one though (can't see what the Maldives one is about -we can't list every paper dealing with every sea level station).

There is no deception whatsoever when every date on the site is from when there WAS such a commission. It amazes me that you feel so adamantly about censoring those results simply because the commission was rotated out of existence in accordance with normal INQUA procedure. Are you listening to yourself? Should we remove the TAR because the TAR is in the past? The commission existed more recently than the TAR. — Cortonin | Talk 17:28, 9 Feb 2005 (UTC)

There is deception. http://www.pog.su.se/sea/ makes no reference to the commission no longer existing. Morner has been told (pers comm) to take down that site. Any casual visitor will assume (a) that the commission continues to exist and (b) that the site in some way reflects INQUA's official position. Neither is true. Morner abused his position to push his personal POV, and continues to: see [2].

There is no reason for him to take the site down. If I were him, I would not. INQUA, like any scientific organization, should not have the authority to erase record of previous work commissioned by itself. This "pers comm" which you claim has asked him to take it down neither should bear authoritative weight, nor apparently does it, since it is apparently undocumented. Instead, that is simply a political dispute from someone who dislikes the results, but instead of disputing the results, is simply calling for their deletion. Uhm, science? — Cortonin | Talk 17:49, 9 Feb 2005 (UTC)

As for "abused his position", I'm not seeing any reference to him having done that outside of that environmentaldefense.org pdf (which appears to be a political action committee, not a research organization), nor am I seeing the response to that letter. Did it even occur? Was it a simple misprint in a bulletin or misquote by an introducer? Details are rather important when you try to hinge so much on a detail like the inclusion or exclusion of the word "former", and details are notably absent here. Move along. — Cortonin | Talk 17:49, 9 Feb 2005 (UTC)

The letter in question, it should be noted, is written by the president of INQUA, not by environmentaldefense.org, which merely hosts the PDF. Graft 18:46, 9 Feb 2005 (UTC)

(William M. Connolley 18:11, 9 Feb 2005 (UTC)) There is every reason for Morner to take the site down: he is abusing his now-severed connection with INQUA. Furthermore the letter, from INQUA, amkes it quite clear that INQUA does not share Morners personal opinions:

Further, INQUA, which is an umbrella organization for hundreds of researchers knowledgeable about past climate, does not subscribe to Mörner’s position on climate change. Nearly all of these researchers agree that humans are modifying Earth’s climate, a position diametrically opposed to Dr. Mörner’s point of view.

(SEWilco 20:09, 9 Feb 2005 (UTC)) So scientist Connolley believes research should be destroyed. Where in that memo did INQUA say the web site should be destroyed?

(William M. Connolley 20:18, 9 Feb 2005 (UTC)) Read what I wrote: its a pers comm. And as for destroying science: there is none on those pages. If there was any, ot could stay, as long as the misleading impression that it is INQUA stuff: which it isn't: its Morners pet opinions. Also, the current text on the wikw page isn't cited properly.

I don't think your personal communications are of any concern in an encyclopedia. Moving on.

(William M. Connolley 10:11, 10 Feb 2005 (UTC)) Pers comm doesn't belong in the body but is appropriate within talk. Are you abandoning "assume good faith"?

You started this thing off by saying the commission didn't exist.

(William M. Connolley 10:11, 10 Feb 2005 (UTC)) I started off saying There *is* no INQUA commission with that name which is correct.

It did, and he was the president of the commission, and that page documents what they concluded during the run of that commission. End of story. Now we document that in the encyclopedia. Whether or not you like the results or the man behind the results, and whether or not the new INQUA president likes the results or the man behind the results, are of no concern whatsoever. If you want to start a Wikipedia page called "The reasons people don't like Nils-Axel Morner", then go right ahead. But this one is about sea level rise and the arguments that have been made about it. — Cortonin | Talk 23:22, 9 Feb 2005 (UTC)

(William M. Connolley 10:11, 10 Feb 2005 (UTC)) The stuff on that page represents Morners personal POV, not INQUAs.

"Morner represents no-one but himself." He has published a lot under his name, but when he spoke for the commission there were others participating. There were studies with co-authors from the commission, notably the Maldives Project paper in 2003 which suggests their constant participation. "New perspectives for the future of the Maldives" was "Received 4 December 2001", so its authors were coworkers at least in 2001. (SEWilco 06:57, 10 Feb 2005 (UTC))

(William M. Connolley 10:11, 10 Feb 2005 (UTC)) You want to quote about global sea level from the Maldives paper (not sure how that would be possible though) then thats fine., But quoting from one bods personal website isn't fine.

The page does not represent "INQUAs POV" because INQUA does not HAVE a singular POV. It is not a body which exists to form POV, it's a body which exists to form commissions, and those commissions exist to investigate phenomena, form conclusions, and report those conclusions, and that's precisely what happened. You seem to be the only one here who has trouble with that concept. — Cortonin | Talk 18:00, 10 Feb 2005 (UTC)

I am not quoting about global sea level from the Maldives paper. I am quoting global sea level work (Morner, 2004) and there is only one 2004 Reference with only Morner's name on it. Estimating future sea level changes from past records doi:10.1016/S0921-8181(03)00097-3 (SEWilco 21:38, 10 Feb 2005 (UTC))

Copied over from Talk:Global warming:

• INQUA finally got sick of him, got rid of the commission, -- Source?
• http://www.pog.su.se/sea which is invalid: this commission doesn't exist anymore.
  • Click on "The Commission" and it says it ended in 2003. SEWilco 08:02, 9 Feb 2005 (UTC)
• The INQUA disbanded the entire commission, rather than simply remove him.
  • g.(i) The officers of a Commission and its subordinate bodies are elected for one inter-Congress period The INQUA didn't have to remove him, simply not reelect him. Where is their discussion of this? SEWilco
    • The INQUA was in the process of restructuring their commissions anyway, so there likely was not a formal discussion on that topic: [3]. (And thus, nothing should be implied here about him as a result of the commission no longer existing, because from the documentation it appears completely unrelated.) — Cortonin | Talk 15:54, 9 Feb 2005 (UTC)
• If you look at the current INQUA commissions [4], you'll see that they are no longer actively investigating sea level change
  • Try clicking on Coastal and marine processes and look for sea level. SEWilco
    • Ah yes, it appears there are still two smaller working-groups working on the topic in there. Leaders, and even members, of INQUA commissions are mandatorily rotated on a regular basis (with optional limited renewals for a term or two in some cases, see bye-laws for details). — Cortonin | Talk 15:54, 9 Feb 2005 (UTC)

The IPCC lists Morner as a TAR reviewer. Anyone know where they published reviewer comments? SEWilco 08:02, 9 Feb 2005 (UTC)

(William M. Connolley 10:11, 10 Feb 2005 (UTC)) Weird or what? SEW "forgot" to copy over my comment on IPCC status, viz: IPCC TAR reviewer is a near-meaningless status of itself..

With its indentation, I didn't realize it was a reply. As a reply, it is not responsive as it does not answer the question: Anyone know where the IPCC published reviewer comments? (SEWilco 21:28, 10 Feb 2005 (UTC))

Here is the full reference to the Maldives study in case anybody needs it: N.A. Mörner. M. Tooley and G. Possert. New perspectives for the future of the Maldives. Global and Planetary Change Vol. 40, No 1-2 pp. 177-182, January 2004. I don't think it's wiki to censor all references to Mörner in a lemma about sea level change. Somebody new to the topic does want to learn about the ongoing scientific debate in which Mörner plays an active role as he has written peer reviewed publications on the subject. The INQUA strawman is sidetracking the issue and doesn't provide a scientific argument why Mörner should be omitted from this lemma.Hans Erren 09:05, 24 February 2006 (UTC)

More Morner

(William M. Connolley 20:49, 10 Feb 2005 (UTC)) So, the text which I've re-removed says:

The former INQUA commission on Sea Level Changes and Coastal Evolution disagreed with the IPCC TAR results, and instead claimed that sea level rise had been measured as constant at around 1.5 mm/yr, and could likely be expected to continue at around that rate since no evidence of acceleration had been observed. [5]

Now the ref above is just to the intro page, and the text sourced to it is not on that page. So where exactly on that site (to which I maintain all my objections above) does that text come from?

Right there in the first paragraph of the coastal section.

(William M. Connolley 21:51, 10 Feb 2005 (UTC)) Right. And what does the bottom of that page say: yes, thats right: Informant: N.-A. Mörner, 1999: in other words, these are his words, not INQUAs.

INQUA doesn't have a mouth anymore than the NSF, NIH, or WHO has a mouth. INQUA is a scientific organization which has a congress which meets every four years, at which point they form commissions. This was one of them, he was its president, and that is their web page. THAT'S ALL THERE IS TO IT. There are 111 sea level experts who signed their names to that commission, and I trust them more than I trust your suspicion. — Cortonin | Talk 00:58, 11 Feb 2005 (UTC)

Additional scientific criticism of the problems with the ocean models used for the IPCC prefered predictions which contradict the observations is also under Sea Level Changes. Now stop erasing that documentation. — Cortonin | Talk 21:00, 10 Feb 2005 (UTC)

I restored the previous format which isolates IPCC studies and the relevant critique of them. Comments on the quality of IPCC sea level work are relevant to evaluation of their information. (SEWilco 21:42, 10 Feb 2005 (UTC))

(William M. Connolley 21:51, 10 Feb 2005 (UTC)) I don't know why you're doing this, but I especially don't understand what Apparently the referenced Question 5 in drafts is now Question 3. is supposed to mean.

OK, fixed that. (SEWilco 03:48, 11 Feb 2005 (UTC))

INQUA response on Morner

This from John Clague, president of INQUA (I wrote to them):

The INQUA Commission on Sea-Level Changes and Coastal Evolution, of which Nils-Axel Morner was President, terminated in August 2003 during the INQUA Congress in Reno. He was not removed as President. All existing INQUA commissions ended at that time during an organizational restructuring.

I don't know whether or not Dr. Morner's views about the IPCC TAR section on sea level change were representative of those of the Sea Level Commission at the time However, his views are definitely not representative of those of members of past and present INQUA Executive Committees. Dr. Morner is free to present his views on sea level change, but I have asked him, on behalf of the current Executive Committee, to cease using his former affiliation with INQUA to promote those views.

Sincerely,

John Clague

President, INQUA

Graft 18:18, 11 Feb 2005 (UTC)

(William M. Connolley 22:00, 26 Mar 2005 (UTC)) Sorry - I missed this before. I'd like to say, I have a similar mail, if anything rather stronger.

Rate of change

The intro implies that sea level rise has been accelerating recently.

The bulk of that occurred before 6 kyr ago. From 3000 years ago to the start of the 19th century sea level was almost constant; since 1900 the level has risen at 1-2 mm/y; since 1992 at about 3 mm/y

I recall reading in contrast that sea level rise has been rather steady during the last few millenia.

I think that we should not state either POV positively as "common knowledge" but provide a source. Direct measurements, or sea floor sediment or other proxies, would also be nice.

(William M. Connolley 21:51, 11 Feb 2005 (UTC)) I've added a source: well the one I used anyway: http://www.grida.no/climate/ipcc_tar/wg1/425.htm. The rise was "steady" but small for the past millenia before 100y ago. Ish.

Along with a description of the various points of view on the RATE of the rise, it would be nice to have some theories about the CAUSE of the rise.

(William M. Connolley 21:51, 11 Feb 2005 (UTC)) Well its anthropogenic guv, innit? (The most recent increase, anyway).

Fred Singer called it a recovery from the ice age and said glaciers have been steadily melting for thousands of years. Let's source this, and if anyone says different, let's source that too.

(William M. Connolley 21:51, 11 Feb 2005 (UTC)) FS is a dubious source for anything, IMHO. But you know what I think of him :-). The 0.1-0.2 mm/y is presumably

Note: this edit was made under the agreed-upon terms of the Wikipedia:climate change team and I therefore hold myself bound by those termes - regardless of what others may do! -- Uncle Ed (talk) 19:01, Feb 11, 2005 (UTC)

Singer's statement from 8 years ago

Global sea level (SL) has undergone a rising trend for at least a century; its cause is believed to be unrelated to climate change [1]. We observe, however, that fluctuations (anomalies) from a linear SL rise show a pronounced anti-correlation with global average temperature--and even more so with tropical average sea surface temperature. We also find a suggestive correlation between negative sea-level rise anomalies and the occurrence of El Nino events. These findings suggest that--under current conditions-- evaporation from the ocean with subsequent deposition on the ice caps, principally in the Antarctic, is more important in determining sea-level changes than the melting of glaciers and thermal expansion of ocean water. It also suggests that any future moderate warming, from whatever cause, will slow down the ongoing sea-level rise, rather than speed it up. Support for this conclusion comes from theoretical studies of precipitation increases [2] and from results of General Circulation Models (GCMs) [3,4]. Further support comes from the (albeit limited) record of annual ice accumulation in polar ice sheets [5]. [6]

(William M. Connolley 21:51, 11 Feb 2005 (UTC)) FS's idea that increasing Ant precip will lower sea level enough to combat thermal expansion is wacky and taken seriously by no-one, which is why he has never published it. Mis-citing Bromwich in his support doesn't help.

Global Change Course at Iowa State University

Dr. Takle stated that it has been estimated that the oceans have risen by 1-2mm/yr. for the last one-hundred years (or about 4 inches total). There are many sources for error, however. These include interannual variations, meteorological and oceanic forcing, historic geographical bias, and vertical land movements. One important thing to note is that over the last 100 years, the rate at which the sea is rising has not increased. [7]

(William M. Connolley 21:51, 11 Feb 2005 (UTC)) I would guess that if you leave out the post-1990 data, that would be true.

Factors known to affect sea level (SL)

Singer lists three factors (first two are from IPCC):

The contribution to SL rise of the past century comes mainly from three sources: (i) Thermal expansion of the warming ocean contributed about 4 cm; and (ii) the melting of continental glaciers about 3.5 cm. (iii) The polar regions, on the other hand, produced a net lowering of SL, with most of this coming from the Antarctic. (The mechanism is intuitively easy to understand but difficult to calculate: A warming ocean evaporates more water, and some of it rains out in the polar regions, thus transferring water from the ocean to the polar ice caps.) The surprising result: When one simply adds up all these contributions (neglecting the large uncertainties), they account for only about 20 percent of the observed rise of 18 cm. The climate warming since 1900 cannot be the cause of the SL rise; something is missing here. (Singer)

global warming and sea level rise

What about the effects of human-induced global warming on SL rise? Will it really increase the rate above its natural value, as predicted by the IPCC? We do have a handle on this question by observing what actually happened when the climate warmed sharply between 1900 and 1940, before cooling between 1940 and 1975. The answer is quite surprising and could not have been derived from theory or from mathematical models. The data show that SL rise slowed down when the climate warmed and accelerated when the climate cooled. Evidently, ocean-water thermal expansion and mountain-glacier melting were less important than ice accumulation on the Antarctic continent (which lowers SL). (ibid.)

Satellite altimetry

"Satellite altimetry indicates an increase from a little less than 2 mm/y to somewhat above 3 mm/y."

No, satellite altimetry has not shown an acceleration, it simply reports a different rate than the land based measurements. The only way to interpret this as an acceleration is to think that the land based measurements were right, but are now wrong, and that the newer satellite measurements are accurate. The far more simpler explanation is that the newer satellite measurements are not yet calibrated perfectly. This is perfectly acceptable as long as we're not in some sort of rush to confirm a pre-expected result. — Cortonin | Talk 19:35, 11 Feb 2005 (UTC)

(William M. Connolley 21:37, 11 Feb 2005 (UTC)) The satellite people certainly don't think they have calibration problems large enough to explain the differnce. Perhaps you should try reading some of the papers?

(SEWilco 21:16, 2 Mar 2005 (UTC)) Cortonin, you might check if these have been published. Deleted from the TAR. [8]

Ch 11 Page 27 Line 16

Shum et al. (1999) and Guman et al. (1999) have combined data from the less accurate GEOSAT altimeter data (late 1986 to late 1988) with ERS and TOPEX/POSEIDON data, using in situ tide-gauge data for cross-calibration. They find a global sea-level trend of 1.0 ±2.1 mm/yr over the 12 year period.

Delete because references not published

Actually, the satellite people solved calibration problems by calibrating to match tide gauges. [9] (SEWilco 22:15, 23 Mar 2005 (UTC))

I deleted the statement "Also, it should be noted that since satellite results are partially calibrated against tide gauge readings, they are not an entirely independent source. [10]" because I believe it to be incorrect. I perform the tide gauge calibration with Gary Mitchum at the University of South Florida. The tide gauge calibration is used to detect drifts in the altimeter, but the calibration is no longer used to correct any drifts in the estimates of sea level from the altimeter, so the measurements are "independent". Leuliett 05:55, 7 January 2006 (UTC)

I also deleted the statement "This includes an apparent increase to 3.7±0.2 mm/yr during the period 1999 through 2004 [11]." First, the error estimate on the trend includes only formal errors on the least squares fit. The tide gauge calibration of the altimetry has an uncertainty of 0.4 mm/yr because of uncertainties in the land motion of the tide gauges.This limits the uncertainty that the rate from altimetry can be verified. Combining the formal error with the calibration error in quadrature would produce an uncertainty of 0.5 mm/yr. Given that the estimated trend in global mean sea level from 1992-2005 is 2.9±0.4 mm/yr and the trend from 1999-2004 3.7±0.5 mm/yr, the two rates are statistically indistinguishable. This is not necessarily "an apparent increase". Second, the tide gauge calibration of Jason data from 2002-2005 has a drift at the 1 mm/yr level, which could produce the recent apparent increase.Leuliett 05:55, 7 January 2006 (UTC)

I deleted the out-of-date statement that TOPEX/POSIEDON has an unknown drift of 2 mm/yr. This drift was largely identified as originating with TOPEX Microwave Radiometer (TMR) in the mid-1990s. The TMR was calibrated. Other smaller sources of drift were identified, in particular Don Chambers at the University of Texas at Austin improved the sea state bias model used for the TOPEX-A and TOPEX-B instruments. The most recent tide gauge calibration of TOPEX shows a drift statistically indistingishable from zero. Leuliett 06:09, 7 January 2006 (UTC)

Clathrates & sea level drop

SEWilco recently added the following text:

Warming oceans can also cause reduced sea levels when methane or carbon dioxide is released from clathrate seafloor ice. Although at present this may cause sea level to fall by 10–146 cm, this can only happen when sufficient time has passed since a preceding change for such ices to accumulate. Such releases of large amounts of gas are also likely to have atmospheric effects. [12]

The paper SEWilco is citing is 6 years out of date. Since then estimates for the magnitude of the modern clathrate reservoir have dropped more than an order of magnitude below the "low" estimate in the paper SEW cites. Mostly because people have finally begun digging up clathrates in volume and have come to realize that most methane ices are only at a few percent of saturation, rather than the 50-100% that people had been assumming. Hence the paper is basically irrelevant to modern climate change.

On longer time scales, I'm not sure. The modern ocean appears to be quite understaturated in methane ices (perhaps because of the high volatility of sea level during recent ice ages). So maybe at other periods in Earth's history there could be a methane reservoir orders of magnitude larger than present. And perhaps the dissociation of that methane could drop sea level by a geologically significant amount. The methane pulse would obviously have the biggest impact on climate, but that might be limited to 100-250 kyr, whereas the ice displacement could last longer. Whether there would ever be enough of a shift to be geologically noticably, I don't know. Dragons flight 00:49, Mar 22, 2005 (UTC)

Estimates have dropped below 2E14 m3? A 100m drop glacial sea level drop should only reduce clathrate by 10%, although other changes may have cleared the field. And I didn't emphasize an atmospheric pulse because methane tends to dissolve in the water when slowly released. (SEWilco 23:06, 22 Mar 2005 (UTC))

My notes give Milkov 2004, Earth Science Reviews, with clathrate inventory figure of 500-2500 GtC (gigatons carbon), with the author favoring the low end of that range. The more commonly quoted number is 10000 GtC, and much larger numbers exist so I assume that 2e14 comes from a reference not a lot smaller than 10000 GtC (I didn't look at the paper in detail). I may have overstated the drop depending on the details, but roughly 10000 to roughly 1000 would be an order of magnitude. At the very least it suggests something on the low end of the 10-146 cm range you state. Dragons flight 23:55, Mar 22, 2005 (UTC)

GtC. Try volume in your source. (1–5)×10^15 m^3. doi:10.1016/j.earscirev.2003.11.002 I believe 2E14 m^3 is Milkov 2001. (SEWilco 07:47, 23 Mar 2005 (UTC))

Okay. Sorry. Thanks. I guess that means Milkov is predicting only 100 GtC in the clathrates? Incidentally, does it strike anyone else as weird that clathrate volumes are reported with respect to the eqivalent gas volume at STP? Screwed with my head when trying to convert GtC to volume on the back of the envelope. Dragons flight 08:13, Mar 23, 2005 (UTC)

Get a helmet and a bigger envelope. The volume needed for this article is clathrate volume. Compared to volume of the contained water in liquid form (with methane having dissolved or escaped to atmosphere). (SEWilco 19:41, 23 Mar 2005 (UTC))

I know that, but the volume stated in the Earth Science Review article are volume of gas equivalent at STP. Given the comparable size scale, I assume that is the form of the number quoted in the abstract of your article. I also assume it is straight forward to convert STP volumes to solid clathrate volumes, and that your article does that at some point in calculating the displacement volume. Dragons flight 20:27, Mar 23, 2005 (UTC)

Explicable

(William M. Connolley 19:54, 23 Mar 2005 (UTC)) SEW has insisted on adding The current rise in sea level observed from tide gauges, of about 1.8 mm/y, is not explicable by the combination of factors above.... Its not clear where he gets this from. The IPCC states: The sum of these components indicates a rate of eustatic sea level rise (corresponding to a change in ocean volume) from 1910 to 1990 ranging from –0.8 to 2.2 mm/yr, with a central value of 0.7 mm/yr. The upper bound is close to the observational upper bound (2.0 mm/yr), but the central value is less than the observational lower bound (1.0 mm/yr), i.e., the sum of components is biased low compared to the observational estimates. [13] which is inconsistent with his text, but consistent with my text: "just about explicable". I was going to add that to the text, but I find that [14] is already there, so SEW's text remains mysterious to me.

See the other changes which were made at the same time in Sea_level_rise#Conflicting_information, which state that there are conflicts in matching observations to factors. (SEWilco 20:42, 23 Mar 2005 (UTC))

I swapped it from "just about" to "within the estimate range". The ranges are quite wide, so that's about as far as the conclusions can go. In addition, the phrase "just about" should be avoided, because if you didn't notice, it means different things depending on which side of the Atlantic you are on. To Americans, "just about" usually means "almost", while to the British, "just about" usually means "just barely". — Cortonin | Talk 22:30, 23 Mar 2005 (UTC)

I just about got the torch out of my boot before the lift caught fire. (SEWilco 22:40, 26 Mar 2005 (UTC))

Morner / INQUA commission

I appreciate the desire to remove mention of the INQUA commission from the Morner section in order to avoid editing conflict here, but I believe this omission is improper. At the time of the reference, Morner was president of that INQUA commission, authorized to coordinate communication within the commission and then speak on behalf of the commission reporting the results of that, and the reference states "Our INQUA Commission ... has a totally different view," which no members of that INQUA Commission have come forward to dispute. (The executive who says Morner does not speak on behalf of the "executive committee" was not, to my knowledge, a member of this particular commission.) — Cortonin | Talk 18:35, 25 Mar 2005 (UTC)

I think if a group of researchers work together to form a conclusion, then it is improper to attribute that conclusion to only one researcher, as it minimizes the contributions others have made. As Morner claims he was speaking on behalf of the commission and representing their views, and no member of the commission has stated otherwise, then I think we have to characterize it as such here for proper attribution of credit. — Cortonin | Talk 18:35, 25 Mar 2005 (UTC)

Normally, I would agree with you, but in this case there seem to be some concerns that Morner's abused his position as president to push his own point of view. Obviously, a key issue in dispute is whether or not the statements Morner wrote were actually representative of the views of the Commission at that time. For the record, of the 8 officers on the current executive commission, 1 is listed on the former sea level commission. And as a matter of fact, that officer is the current president, John Clague, who is also the individual above who wrote that he did not know if Morner's opinion was representative of the Sea Level Commission at that time.

Given the ambiguity on whether Morner was properly representing Commission views, I would be willing to accept compromise language to the effect that he made those statements while head of the INQUA commission, with the implication that he had plentiful opportunity for consultation, but while still avoiding the disputed issue of whether those statements were adequately representative of the Commission's views as a whole.

One thing that we could do is email other officers / members of the former INQUA sea level commission and see if they feel that Morner's statements were truly representative of the commissions views at that time. Dragons flight 19:19, Mar 25, 2005 (UTC)

I don't recall seeing any prominent questioning that the reference above is the view of the commission at that time. The only prominent questioning presented was this reference by the current INQUA executive committee president about whether or not Morner claimed at a seminar that he IS the sea level commission president or that he WAS the sea level commission president. I think at best this counts as someone angry at a rumor, and it seems clear that he's angry more because of the views Morner is expressing than because of the rumor he heard. This might seem important to people looking for ways to discredit people promoting a certain view, such as on the sites hosting that document, but I don't think it's particularly pertinent to the discussion here, since it doesn't directly question the content of the reference. — Cortonin | Talk 02:06, 26 Mar 2005 (UTC)

I agree with your assessment that we don't need to clarify the amount of consultation he had with the commission, since it's not specifically described in the reference. It just shouldn't be presented as only his conclusion since the reference implies that others helped him formulate it. I think we can write it most clearly by something along the lines of "Nils-Axel Morner, then President of the INQUA Commission on Sea Level Changes and Coastal Evolution, reported the commission's conclusion...". (Perhaps with something equivalent, but better worded, in place of "reported the commission's conclusion") — Cortonin | Talk 02:06, 26 Mar 2005 (UTC)

How about: "Nils-Axel Morner, acting in his capacity as President of the INQUA Commission on Sea Level Changes and Coastal Evolution, stated: ..."? That would seem to convey the view that it was more than just his opinion while avoiding the question of how much input the commision had in forming this conclusion.

However, I do think that if this is expressed as an official view, then neutrality requires that it be noted that INQUA as a whole does not presently endorse this view. I would suggest adding a note to the end of the statement saying something like: "More recently, the Executive Commission of INQUA has stated that these views do not represent the opinion of INQUA as a whole." Dragons flight 03:29, Mar 26, 2005 (UTC)

I think your proposed statement is an acceptable wording, even if a little overly-formal sounding. As for the disclaimer, I don't think this is necessarily necessary. By written INQUA policy, the conclusions of commissions never officially represent the view of INQUA as a whole, which is a reasonably standard thing for any scientific society which desires to preserve academic freedom (in order to keep politics out of science). I'm not even sure if the executive committee is authorized to speak on behalf of the scientific views of INQUA as a whole, so at best it could be said that the current executive committee has expressed disagreement with whatever view Morner happened to be promoting at the seminar in question (which is not necessarilly the sea level rise issue). — Cortonin | Talk 19:21, 26 Mar 2005 (UTC)

Yes, but most readers of Wikipedia are not likely to know about INQUA policy, or for that matter the conventions of scientific organizations. Nor would I neccesarily agree that this is a standard thing. Several of the major societies have political lobbying wings (e.g. [15], [16], [17], [18]), which to varying degrees define the official position of the organization. I should note that such policy directions are often set by the elected representatives within the organization rather than a more direct poll of membership, or similar consensus building exercise. In this sense, it would be common to consider the executive commission of INQUA, as the elected representatives of the organization, to have the authority to speak on behalf of the organization as a whole. Also, I believe the above posted email from John Clague is quite clear that the Executive Commission is specifically rejecting Morner's criticism of the IPCC TAR sea level section, which is directly the content of the quote we would be disclaiming. As before, I definately believe that a disclaimer is appropriate, but I would certainly entertain alternative ways for how to phrase it, if you or others have suggestions. Dragons flight 20:08, Mar 26, 2005 (UTC)

The Clague reference states that he's responding to criticisms of "climate science" that Morner made in July of 2004, which was well past the date of the Morner reference being discussed, which was on sea level rise. It's possible that Morner was lecturing on the exact same topic, but this is by no means specified. — Cortonin | Talk 22:36, 26 Mar 2005 (UTC)

Are we looking at the same reference: Talk:Sea level rise#INQUA response on Morner? Seems to be on sea level change to me. Dragons flight 22:48, Mar 26, 2005 (UTC)

Nope, we're talking about different ones. I'm referring to this reference. Although the email pasted into this talk page makes it more clear that Clague is only speaking on behalf of the executive committee, and not for the entirety of INQUA. However, I would say the president of an executive committee of a scientific society has no authority to order someone to stop speaking about the conclusions reached in a former commission, or to change the contents of his or her resume, CV, or introduction. I think this talk page has simply gotten in the middle of two people who don't get along on a personal level, and this has nothing to do with the topic being described here. — Cortonin | Talk 23:03, 26 Mar 2005 (UTC)

As for the other scientific societies, their political lobbying wings are typically only supporting political positions, relating to funding or policy about science. This doesn't usually include making statements about science. (The APS for example has a statement about nuclear testing not being necessary for the U.S., but this is about policy rather than science.) Policy can be set by elected representatives, but decisions about science aren't typically made by elected representatives. But you are right that readers should not be expected to know of such customs. I would say that if someone could verify that Morner was lecturing on sea level rise at the July 2004 seminar being disputed, then it would be okay to include a comment that claims the "current" executive committee of INQUA disputes this. But if he was lecturing on some other more general topic, then the executive committee's comments only apply in that they express dislike or disapproval of Morner, which would be relevant on a Morner page, but I would think not here. — Cortonin | Talk 22:36, 26 Mar 2005 (UTC)

"Nils-Axel Morner, speaking for a Commission on Sea Level Changes and Coastal Evolution, stated: ..." INQUA doesn't get blame nor credit. (SEWilco 22:42, 26 Mar 2005 (UTC))

(Too many colons, resetting indent) I would accept SEWilco's compromise without disclaimer. If we don't specifically attribute the position to INQUA, I am willing to ignore the fact that prominent members within INQUA disagree with Morner's position. I would suggest one small change however to: "Nils-Axel Morner, speaking as president of a Commission on Sea Level Changes and Coastal Evolution, stated: ..." Saying that he speaks "for" them suggests a level of approval for his statements that doesn't seem to be well established. Dragons flight 23:28, Mar 26, 2005 (UTC)

Regional Sea Level Rise

WMC added a comment about sea level rise not being globally uniform. This is true and fine and good, but I think it is likely to appear rather wacky to the casual observer. After all, you put more water in a bucket and it is going to go up uniformly.

I would like to add a sentence or two explaining why it is not uniform. However, I don't really understand the issue well enough myself. For the most part you are talking about the impacts of local climate changes shaping (or reshaping) the height of the ocean, yes? For example a consistent wind can work against gravity to keep parts of the ocean a little bit higher than other parts, right?

Is this the dominant contribution to regional variability? I also believe that the regions with the most anomalous behavior will be places like Scandanavia and Canada where you still have large glacial rebounds going on. Of course, that won't effect most parts of the world.

Could someone, perhaps WMC, clarify this issue?

Dragons flight 20:44, Apr 11, 2005 (UTC)

(William M. Connolley 21:08, 11 Apr 2005 (UTC)) I believe that the prime ref for this is Gregory, 2001 (see IPCC). I'm not sure really of the balance of effects, but some of them are: dynamics (ocean circ changes); inverse barometer; salinity changes; T changes.

Removing Florida

(William M. Connolley 17:56, 19 May 2005 (UTC)) I removed:

Some evidence also suggests that, during the Medieval Warm Period, sea level in Florida stood 0.5 m higher than today between 1200-700 years BP (Fairbridge, 1974; Stapor and others, 1991).[19]

This evidence appears incompatible with the history of SRL, and is far more likely to be accounted for by more local movements.

"SRL"? (SEWilco 18:38, 19 May 2005 (UTC))

(William M. Connolley 19:26, 19 May 2005 (UTC)) Sea Rise Level. Oops. SLR. Alternatively, Steve R Leonard, an ex-roommate of mine.

WMC, presumably you mean that there is some widely agreed upon body of evidence that would be incompatible with a sea level 0.5 m higher than today 1000 years ago. If such evidence does exist could you provide some citations? As far as I have been aware, the available data has basically been too erratically spaced in time or of too poor vertical resolution to adequately constrain sub-meter fluctuations on centennial time scales once one goes more than a few hundred years into the past. Which is not the same as saying that the Florida result is right, but I'm not aware of measurements that would compel me to dismiss it out of hand. Dragons flight 21:25, May 19, 2005 (UTC)

(William M. Connolley 14:19, 20 May 2005 (UTC)) I hoped you would comment. The chances are you know more about it than me. I can try to dig out some citations though. Those Florida data do seem to be contested, though I don't know whether there is a current mainstream interpretation.

I'm not sure there is much about sea level fine structure that isn't contested. This cartoon [20], I think is a pretty good representation of the debate (even though from a dubious source). Most everyone who tries to measure sea level fine structure sees wiggles. Some accept those wiggles as true eustatic variations and other ascribe them to measurement uncertainty and local variability, and argue that the true curve is much smoother. Historical accounts and port cities tell us that the variations can't have been huge, but once you get down to the 30-50 cm level there don't seem to be a lot of constraints, or at least that was the opinion I formed the last time I went trolling in this area. Maybe the field has matured since then. Depending on what turns up, the best thing to do may simply be to say that A says this and B says that, and the truth is still undecided. Dragons flight 15:35, May 20, 2005 (UTC)

(William M. Connolley 19:13, 20 May 2005 (UTC)) There is:

The geological indicators of past sea level are usually not sufficiently precise to enable fluctuations of sub-metre amplitude to be observed. In some circumstances high quality records do exist. These are from tectonically stable areas where the tidal range is small and has remained little changed through time, where no barriers or other shoreline features formed to change the local conditions, and where there are biological indicators that bear a precise and consistent relationship to sea level. Such areas include the micro-atoll coral formations of Queensland, Australia (Chappell, 1982; Woodroffe and McLean, 1990); the coralline algae and gastropod vermetid data of the Mediterranean (Laborel et al., 1994; Morhange et al., 1996), and the fresh-to-marine transitions in the Baltic Sea (Eronen et al., 1995; Hyvarinen, 1999). These results all indicate that for the past 3,000 to 5,000 years oscillations in global sea level on time-scales of 100 to 1,000 years are unlikely to have exceeded 0.3 to 0.5 m. Archaeological evidence for this interval places similar constraints on sea level oscillations (Flemming and Webb, 1986). Some detailed local studies have indicated that fluctuations of the order of 1 m can occur (e.g., Van de Plassche et al., 1998) but no globally consistent pattern has yet emerged, suggesting that these may be local rather than global variations.

from http://www.grida.no/climate/ipcc_tar/wg1/423.htm#1131

Which seems to basically amount to: We probably aren't fluctuating more than 0.5 m, but the IPCC isn't prepared to commit to saying much more than that. This is probably about the tack we need to be taking. Incidentally, several of the micro-atoll people (e.g. Woodroffe) present fairly strong evidence, in the form of former coral formations now above low tide, that sea level at many of these islands had to be at least a little higher than present at some point during the last 3000 years. However, other authors (e.g. Morhange) argue that sea level has never been higher than modern day. One fairly strong piece of evidence on that side is a paleolithic cave painting half submerged under present sea level, but which is only smudged below present sea level and not above it (i.e. sea level was never higher than now at this location) See Figure 7: [21]. Of course some of these effects may reflect unrecognized local tectonic variability. Dragons flight 21:34, May 20, 2005 (UTC)

Incidentally, I found a fairly good related paper doi:10.1016/S0012-821X(98)00198-8, which shows among other things the multi-meter scatter that can be observed in measurements over the last 10 kyr. Whether this is signal or noise is a basically the essence of the debate. This paper basically treats it as noise. Also, the IPCC cites doi:10.1016/S0012-821X(99)00289-7 for the notion that sea level rises 0.1-0.2 mm/yr on average over the last 3000 years, but I can't see where this claim is supported in the source which basically shows constant sea level over the last 3 kyr (plus some scatter, Figure 8b). Dragons flight 21:34, May 20, 2005 (UTC)

Breaking up this article

I would like to propose that this article be broken into two bits. One to stay here discussing global warming related sea level rise and offer some perspective since the last glacial maximum, and another to reinstate sea level change (presently a redirect to here) and deal with longer term records and processes unrelated to modern global warming. Dragons flight 00:27, Jun 3, 2005 (UTC)

(William M. Connolley 16:22, 5 Jun 2005 (UTC)) OK by me. You're the person to do it.

Waaaay too complicated

Listen, I know that this is a very complicated and contested subject, but I feel that the wikipedia entry is too complicated. Too many charts, too many quotes, not enough readability. I came to this page wanting to learn about Sea Level Rise, and am leaving knowing little more than when I came. Could someone who understands and has digested all of this, trim down the quotes and tables into more readable summaries? --MatthewJ 23:42, 13 July 2005 (UTC) <-(actually a fairly intelligent human being)

Yeah, yeah, we all know it's complicated. Part of the problem is that this is Wikipedia's only article on sea level changes right now. There is a stated intention to create an article on long-term sea level change and pare this down to just the recent sea level rise, but those of us qualified to do it, haven't been rushing to it.  ;-) Dragons flight 00:00, July 14, 2005 (UTC)

I agree with the break, but I'd suggest that maybe sea level would be the article to place that material. In particular, the short-term changes table would happily move across from here to sea level, plus geological changes, and then develop from there. Rd232 21:48, 1 August 2005 (UTC)

Some of the figures contradict each other

• In "Glaciers and ice caps": 68.8 m rise if all antarctic and greenland melts

• "Geological influences": 80 m

• "Greenland contribution": 7 m in at least 1000 years

• "Polar ice": >60 m for Antarctica and 7 m for Greenland (why here again?), Greenland needs at last 1500 years to deglaciate

Where do these figures come from and why do they differ so much (80m vs. 67m, 1000 vs 1500a)? Are there other contradictions I have overlooked?

Side note: Why are the figures for Greenland and glaciers (repeated) in the "polar ice" section? 217.185.37.70 10:57, 2 September 2005 (UTC) (sorry, no account in the english wikipedia)

There are indeed several estimates for various sources. There is no single number to use. (SEWilco 15:42, 2 September 2005 (UTC))

SEWilco bot's changes

SEWilco today converted the inline links of this article to his pet footnote style. He is well aware that other editors of climate related articles are opposed to this change and is currently the subject of an RFC and ARBCom case in part related to similar undiscussed changes on other climate articles. I have posted this undiscussed change as evidence on the arbcom case [22]. I would appreciate it if SEW would revert his changes and instead seek consensus here. Vsmith 18:19, 16 December 2005 (UTC)

Someone posted unsourced material. I updated with a source, and provided details on the source in the Notes section. I also am a significant contributor to this article, and I maintained the existing style of numbered links while adding my source. If the article is owned by someone please label it as such. The Notes section contains details about sources which are preferred by Wikipedia:Verifiability policy. (SEWilco 20:26, 16 December 2005 (UTC))

If there's consensus on the page to change to footnotes, you won't find me interfering, SEW, but you can't go around imposing your own preference against objections. And please stop quoting policy in your favor, because WP:V says embedded links are acceptable, and WP:CITE says where there is disagreement about citation style, defer to the style used by the first contributor. Please understand that these single-issue style campaigns — whether against footnotes, BCE, or particular spellings — always cause trouble. SlimVirgin ^(talk) 20:32, 16 December 2005 (UTC)

WP:V also prefers more citation detail over minimal information. I followed the numerical link style. Stop deleting information. (SEWilco 07:02, 17 December 2005 (UTC))

Can you show me where WP:V says that, please? SlimVirgin ^(talk) 07:04, 17 December 2005 (UTC)

• OK, in addition to the recent poll [23]:
• "The goal of Wikipedia is to become a complete and reliable encyclopedia, so editors should cite credible sources so that their edits can be verified by readers and other editors."[24]
• "add a full citation in the References section"[25]
• "note that Wikipedia:Cite sources is not policy: providing some information about your sources is more important than using a particular format."[26]
• "It is unreasonable to expect other editors to dig for sources to check your work, particularly when the initial content is questionable. The burden of evidence lies with the editor who has made the edit. Editors should therefore be specific, avoid weasel words, and provide references,"[27]
• "adding a full citation for Smith 2005 in the References section at the end of the article"[28]

(SEWilco 08:25, 17 December 2005 (UTC))

Where does it say, as you keep claiming "WP:V also prefers more citation detail over minimal information"? It doesn't say that anywhere. It requests some citation information in the form of embedded links or Harvard references in the text, with full citation information in the References section, or in the Notes section if footnotes have been used. Failing that, it says it prefers some source information over none, and adds that the format ultimately doesn't matter. Nowhere does it say what you have been claiming of it for months. SlimVirgin ^(talk) 08:30, 17 December 2005 (UTC)

"A spokesperson" is not enough of a source, giving the name of the spokesperson is better, and identification of the source, author, and publisher should be made. Also says that sources have to be identifiable for credibility, full citations should be given, information about sources is important, references should not require digging, add a full citation... Maybe you should look back at a version from months ago before your editing also. (SEWilco 09:22, 17 December 2005 (UTC))

SEW - please stop this nonsense. The issue is not information, its you trying to push your pet reference style. William M. Connolley 15:34, 18 December 2005 (UTC).

The issue is information. WP:V and WP:CITE require more complete references, whether you prefer unsupported claims or not. (SEWilco 17:51, 18 December 2005 (UTC))

The issue is SEWilco obstinately pushing his notes system against consensus - see [29] the current arbitration case. Neither WP:V nor WP:CITE require footnotes, more information is easily added into a proper references section without the redundant footnotes as you well know. I would reccommend that you consider the consequences of your contemptuous actions in view of the link provided above. Vsmith 04:53, 19 December 2005 (UTC)

The issue is information. I added citation information while retaining the existing style. Read the repeated bold text in WP:CITE about required reference section information. (SEWilco 06:38, 20 December 2005 (UTC))

SEW, you are descending into madness here. Look at the proposed decision Wikipedia:Requests_for_arbitration/Climate_change_dispute_2/Proposed_decision - you just cannot get away with this stuff. Your apparent inability/refusal to hear what people are trying to tell you does you no good. Please listen to reason. William M. Connolley 21:24, 19 December 2005 (UTC).

Whatever it says, the "Proposed decision" was not based on evidence so I stopped participating. Other required parties also never participated, which is part of the reason the case has been invalid since it began. (SEWilco 06:38, 20 December 2005 (UTC))

Look above at my hearing and responding to people. Look above at people who are not hearing what I am saying. Or else who don't care about information, rules, and policy. (SEWilco 06:04, 21 December 2005 (UTC))

Dead links

Added some inliners to ref section. Found a couple dead ones: #17 http://www.pog.su.se/sea/HP-14.%20IPCC-3.pdf leads to a 404. Also #21 http://news.independent.co.uk/environment/article301493.ece leads to the current days news, a search for the Greenland glacier brings up a start of the article - but subscription required for full article. These are also problems on SEW's notes. Vsmith 02:32, 20 December 2005 (UTC)

So fix the citations. The failures are hinted at in the citations when the title is a URL. (SEWilco 06:40, 20 December 2005 (UTC))

If you are interested in reading the material referenced by a dead link, try finding a Google cache. For example, a cached version of http://www.ldeo.columbia.edu/~mstuding/wais.html, which appears to be dead, can be found at http://www.google.com/search?q=cache:v8VT2VEdUDwJ:www.ldeo.columbia.edu/~mstuding/wais.html+%22West+Antarctic+ice+sheet%22+site:columbia.edu&hl=en&ct=clnk&cd=2&gl=us. I found it by searching for <<"West Antarctic ice sheet" site:columbia.edu>>. —The preceding unsigned comment was added by 70.100.60.2 (talk) 01:06, 3 February 2007 (UTC).

Obsolete references

Some of the entries in References are not mentioned in the article text, so I could not link to them. Are any of those References without backlinks still in use, or have edits removed their associated text? (SEWilco 05:55, 21 December 2005 (UTC))

Why would you consider them obsolete? When creating a new short article it is common, and I would say adviseable, to list the general references as sources to back up the info. Every point or fact in the article does not need to be related to a particular reference. Only when specific detail or arguements are added, are specific sources linked via preferably Harvard style citations (my preference). Do you think that every source must have a backlink? If so, then your footnote system has more problems.

These perhaps original references need to be kept as general sources and perhaps as a history of the article development. Only when and if this article is split into two separate articles do then we need to decide which general reference goes with which split. Cross that bridge then, for now don't remove a source simply because you cannot make a specific backlink. Backlinks as part of your footnote scheme are here a moot point as I see no consensus for using that scheme. Vsmith 23:22, 22 December 2005 (UTC)

Stuff

I've rm'd:

Over the last million years the sea level has changed by tens of meters many times, while many fewer variations of as much as 100 meters have taken place. Although during the past million years the sea level has generally been lower than it presently is, over geologic time scales the sea level has often been 100-200 meters higher than in recent times.

I don't think this belongs in the intro of the page as it stands. Maybe it belongs in the split up version as per DF's idea.

SEW: I don't know what you've done to improve the refs. But whatever you do will all be lost if you persist in pushing against what everyone else wants. I certainly don't have the patience to go checking through a pile of minor changes. How about listing whatever cleanup the refs need, that would actually be a useful service. William M. Connolley 09:46, 21 December 2005 (UTC).

The sumamry of the range of sea level change seems appropriate for an introduction on the subject. The cleanup was being done, and you're authorized to delete stuff that you don't have time to "check"? Do you need instructions on how to create a 'diff' of a range of revisions? (SEWilco 05:34, 22 December 2005 (UTC))

Your changing the refs around puts so many minor diffs in place that its tedious to check through. If you want to make changes to the text, it would be helpful if you could do just that, and leave it for others to have a look at. Similarly, if there are any fixes that the refs need, and you have found, it would be helpful if you could list them, here on talk.

To compare across many minor diffs with a single diff, click on the round radio button near the left side of the oldest version to begin with. Then click on the radio button next to the newer version to compare with, and click on the "Compare selected version" button. Nevertheless, I don't think your lack of time is a reason for you to make Wikipedia worse. (SEWilco 14:55, 22 December 2005 (UTC))

Gosh really? Sadly when I try that I find some unwise person has fuggled so many of the references that diffs show up scattered throughout the article. If that person were to leave the references alone for a bit we could perhaps discuss the text changes. William M. Connolley 16:18, 22 December 2005 (UTC).

It's awfully difficult, when someone keeps deleting the required citations. And Vsmith inserted a handful of citations whose relevance is difficult to identify, some of which it turns out were expanded versions of existing numbered citations (I helped him by moving them to the existing citation entry, as I'm sure he didn't intend to change the existing style of the new several dozen citations). (SEWilco 21:22, 22 December 2005 (UTC))

Aw gee, thanks for the help, but no thanks. I was just adding existing inline text refs into references in the reference section - there is more to do including some cleanup. But as has been well documented, the footnotes scheme is currently out. Now, please stop pushing it. Content edits should be made separately from any housekeeping referencing edits. Yeah, it appeared to me there was an effort to mix content in with ref format edits to make the inevitable reversion more difficult - your strategy is blatantly obvious. Now, I am also aware that you claim to be ignoring the pending arbcom decision for whatever reasons, please don't - and note the relevance of that decision here. Vsmith 23:39, 22 December 2005 (UTC)

I am no longer participating in the arbcom case, as the arbcom is proceeding the way it wishes to rather than following Wikipedia policies, including its own Arbitration Policy under whose power it is acting; evidence is ignored, so no need to waste time providing more evidence (but all that is in my statement in the case). In this article I am acting as an editor who made a relevant change and followed WP:CITE and WP:V in creating missing citations. (SEWilco 04:06, 23 December 2005 (UTC))

The arbcomm case is now resolved, the answer is SEWilco should not use a bot to convert citations on articles, nor should he manually convert citation styles on any articles. That should mean peace reigning over the citation format, and we can actually work on the content of the article. How nice. Wikipedia:Requests_for_arbitration/Climate_change_dispute_2. William M. Connolley 22:18, 23 December 2005 (UTC).

So you may continue to spew material without feeling the need to make it verifiable. (SEWilco 04:00, 24 December 2005 (UTC))

Sigh. This is merely a pointless insult. The material remains verifiable. You could try working with us to improve the articles. William M. Connolley 09:33, 24 December 2005 (UTC).

As you indicate below, you can't seem to use unlinked references to verify the material which the references are supporting. Please help improve the references instead of deleting what you do not understand. (SEWilco 03:22, 7 January 2006 (UTC))

Split the article?

Back in march, and again more recently at the peer review, DF wrote:

I would support the creation of two pages, "sea level change" that deals primarily with the long term variations relavant to geology and evolution, and a second page at perhaps "recent sea level rise" that deals with the last 20 kyr or so and incorporates virtually all of the material on this current page. Dragons flight 22:34, Mar 26, 2005 (UTC)

Looking back, I now see that the person that did the merge was... me. However, I shall argue that at the time the split was different. So I don't mind. I might even do it. Anyone else? William M. Connolley 11:14, 22 December 2005 (UTC).

Hmm... this relates closely to my suggestion of changing the name below. It is a lot of reading for one article, though the topics are so closely connected it's a shame to split them up. I don't know. Richard001 01:12, 15 September 2007 (UTC)

yet more Morner

Morner never represented anyone other than himself; his pet website has now been taken down (falsifying Cortonins prediction, no great surprise) so I've removed what is now unsupported text. I also took him out of the references: there was no obvious reason for those two refs: as far as I can tell they aren't used. And one of them has for abstract In the last 5000 years, global mean sea level has been dominated by the redistribution of water masses over the globe. In the last 300 years, sea level has been oscillation close to the present with peak rates in the period 1890–1930. Between 1930 and 1950, sea fell. The late 20th century lack any sign of acceleration. Satellite altimetry indicates virtually no changes in the last decade. This is (a) ungrammatical and (b) a pile of junk (just look at the pic); there is no reason to refer our readers to it. William M. Connolley 09:42, 24 December 2005 (UTC).

If you can't find the reason for references then obviously links to references are needed. (SEWilco 03:19, 7 January 2006 (UTC))

Just to check, is this the same Morner who dowses [30]? If so, should we qualify the added/removed/added remark he makes about predictions of sea-level rise? His credability is somewhat strained by this sort of thing. --Plumbago 10:02, 11 January 2006 (UTC)

Yup, its the same Morner :-( William M. Connolley 18:18, 11 January 2006 (UTC)

SEW and I seem to be having a minor edit war over:

Nils-Axel Mörner, states: "All handling by IPCC of the Sea Level questions have been done in a way that cannot be accepted and that certainly not concur with modern knowledge of the mode and mechanism of sea level changes. ... It seems that the authors involved in [the sea level chapter of the IPCC report] were chosen not because of their deep knowledge in the subject, but rather because they should say what the climate model had predicted. This chapter has a low and unacceptable standard." [31]

I've never liked Morners stuff: its scientifically without merit, and non-notable. The sole justification for putting it in was his status on INQUA, which he unfortunately used to push his own opinions. Now he no longer has that status and INQUA made him take the web site down (which is why SEW is obliged to go to the webarchive to find the link), so the sole justification is gone. I invite others to comment. William M. Connolley 18:18, 11 January 2006 (UTC).

Peer review - admin needed

SEW seems to have degenerated to simple vandalism - see [32]. Can someone with admin powers please move the page back Thanks... William M. Connolley 15:03, 5 January 2006 (UTC).

Done - hopefully, let me know if I messed anything up :-) Vsmith 16:17, 5 January 2006 (UTC)

Thanks! Note that SEW also listed his version of this at Wikipedia:Requested_moves#2006-01-05. Ive replied there so hopefully noone will re-do this! William M. Connolley 16:38, 5 January 2006 (UTC).

That was not vandalism, that was a reversion of material which William M. Connolley had deleted. Reversion was incomplete due to the page history, so completion was requested through Requested moves. (SEWilco 03:18, 7 January 2006 (UTC))

I didn't delete it, I moved it to another page, which I clearly linked. SEW - you're in danger of turning into a troll. Please pull back from the brink. William M. Connolley 15:54, 7 January 2006 (UTC).

L's changes

L made some changes which I'd like to see sourced.

Removed: Also, it should be noted that since satellite results are partially calibrated against tide gauge readings, they are not an entirely independent source. [33]. This seems fair enough from the source, so I'm unsure.

Removed bold bit from: Since 1992 the TOPEX and JASON satellite programs have provided measurements of sea level change. The current data are available at [34]. The data show a mean sea level increase of 2.8±0.4 mm/yr. This includes an apparent increase to 3.7±0.2 mm/yr during the period 1999 through 2004 [35]. Thats not a brilliant source, and could count as Original Research.

Removed true differences between satellites and tide gauges;. This I find hard to understand: one possibility is definitely that the satellites (which measure the global ocean) are seeing something different to the tide gauges (which only see the coasts).

William M. Connolley 16:03, 7 January 2006 (UTC).

Copied the Leuliett's previous comments from old Altimetry section above: (Vsmith 16:25, 7 January 2006 (UTC))

I deleted the statement "Also, it should be noted that since satellite results are partially calibrated against tide gauge readings, they are not an entirely independent source. [36]" because I believe it to be incorrect. I perform the tide gauge calibration with Gary Mitchum at the University of South Florida. The tide gauge calibration is used to detect drifts in the altimeter, but the calibration is no longer used to correct any drifts in the estimates of sea level from the altimeter, so the measurements are "independent". Leuliett 05:55, 7 January 2006 (UTC)

It would still be nice to see a source for this, though William M. Connolley 21:10, 7 January 2006 (UTC).

I also deleted the statement "This includes an apparent increase to 3.7±0.2 mm/yr during the period 1999 through 2004 [37]." First, the error estimate on the trend includes only formal errors on the least squares fit. The tide gauge calibration of the altimetry has an uncertainty of 0.4 mm/yr because of uncertainties in the land motion of the tide gauges.This limits the uncertainty that the rate from altimetry can be verified. Combining the formal error with the calibration error in quadrature would produce an uncertainty of 0.5 mm/yr. Given that the estimated trend in global mean sea level from 1992-2005 is 2.9±0.4 mm/yr and the trend from 1999-2004 3.7±0.5 mm/yr, the two rates are statistically indistinguishable. This is not necessarily "an apparent increase". Second, the tide gauge calibration of Jason data from 2002-2005 has a drift at the 1 mm/yr level, which could produce the recent apparent increase.Leuliett 05:55, 7 January 2006 (UTC)

OK, happy with that. William M. Connolley 21:10, 7 January 2006 (UTC).

I deleted the out-of-date statement that TOPEX/POSIEDON has an unknown drift of 2 mm/yr. This drift was largely identified as originating with TOPEX Microwave Radiometer (TMR) in the mid-1990s. The TMR was calibrated. Other smaller sources of drift were identified, in particular Don Chambers at the University of Texas at Austin improved the sea state bias model used for the TOPEX-A and TOPEX-B instruments. The most recent tide gauge calibration of TOPEX shows a drift statistically indistingishable from zero. Leuliett 06:09, 7 January 2006 (UTC)

OK. I'd still like my last point (true differences between satellites and tide gauges;) addressed, though. William M. Connolley 21:10, 7 January 2006 (UTC).

New paper: acc of rate

This [38] is just out in GRL. I haven't read it, but it sounds interesting, and may lead to some statements on the page being modified:

Multi-century sea-level records and climate models indicate an acceleration of sea-level rise, but no 20th century acceleration has previously been detected. A reconstruction of global sea level using tide-gauge data from 1950 to 2000 indicates a larger rate of rise after 1993 and other periods of rapid sea-level rise but no significant acceleration over this period. Here, we extend the reconstruction of global mean sea level back to 1870 and find a sea-level rise from January 1870 to December 2004 of 195 mm, a 20th century rate of sea-level rise of 1.7 ± 0.3 mm yr−1 and a significant acceleration of sea-level rise of 0.013 ± 0.006 mm yr−2. This acceleration is an important confirmation of climate change simulations which show an acceleration not previously observed. If this acceleration remained constant then the 1990 to 2100 rise would range from 280 to 340 mm, consistent with projections in the IPCC TAR.

I hate it when people dump just-published papers in, so I won't; but I'll put it here in case I forget.

William M. Connolley 23:16, 7 January 2006 (UTC).

Tuvalu

I removed:

Despite President Gayoom speaking in the past about the impending dangers to his country, the Maldives, research found that the people of the Maldives have in the past survived a higher sea level about 50-60 cm and there is evidence of a significant sea level fall in the last 30 years in that Indian Ocean area.

I can't see a source for this, and it doesn't sound right to me. Feel free to re-insert it if you can find a source. William M. Connolley 18:25, 11 January 2006 (UTC).

It's here[39]:

Moerner, N.-A., 2004b. The Maldives Project: a future free from sea level flooding. Contemprary South Asia, 13 (2), p. 149-155. Moerner, N.-A., Tooley, M. & Possnert, G., 2004. New perspectives for the future of the Maldives. Global Planet. Change, 40, 177-182.

Hans Erren 21:41, 22 January 2006 (UTC)

Thanks for the anti-green ref. Did you read it? This makes it pretty clear there is a big problem with:

Reuters has reported other Pacific islands are facing a severe risk including Tegua island in Vanuatu, data shows no net sea level rise. According to Patrick J. Michaels, "In fact, areas to the west such as [the island of] Tuvalu show substantial declines in sea level over that period."[40] Despite President Gayoom speaking in the past about the impending dangers to his country, the Maldives, research found that the people of the Maldives have in the past survived a higher sea level about 50-60 cm and there is evidence of a significant sea level fall in the last 30 years in that Indian Ocean area.[41]

Michaels by himself isn't a source. OTOH a Woodworth actual paper clearly is. And since Woodworth rubbishes Morner, its clear that the bald statement that sea level has fallen around the Maldives can't stand. At best it has to be disputed. Quoting from Woodworth [42] the suggestion of such a fall has been examined from meteorological and oceanographic perspectives and found to be implausible. A number of met-ocean data sets and regional climate indices have been examined, at least one of which would have been expected to reflect a large sea level fall, without any supporting evidence being found. In particular, a suggestion that an increase in evaporation could have caused the fall has been demonstrated to be incorrect. Without any real evidence for a hitherto-unrecognised process which could lead to a sea level change as significant as that proposed by the fieldwork team, one concludes that a rise in sea level of approximately half a metre during the 21st century, as suggested by the Intergovernmental Panel on Climate Change Third Assessment Report, remains the most reliable scenario to employ in future studies of the islands.

Dunkirk transgressions

HE added some stuff to the intro about "Dunkirk transgressions", but no refs. Its not obviously supported by the graphs in the article; and if this is the Dunkirk in France, its likely to be mostly isostatic rebound. Comments? William M. Connolley 14:09, 28 January 2006 (UTC).

The Dunkirk (also Duinkerke) refer to a series of dune and salt marsh deposits in the vicinity of Dunkirk, Belgium. The original interpretation of these deposits as large-scale changes in sea level has been largely discredited by work indicating these deposits lack spatial synchroncity (i.e. even within the Netherlands they don't seem to have consistent ages from site to site). Hence they are most likely to be the result of tidal embayments and other local features changing the mixing rate between the marshes and the ocean. Scientifically, the theory of Dunkirk transgressions is probably not quite dead yet, to the extent that there are probably still people referencing the Dunkirk model, but there is to my knowledge no reliable evidence that these are global events. Also, the Dunkirk terminology is not commonly used even among people who care about sea level. I have removed the reference from the introduction. Dragons flight 18:22, 28 January 2006 (UTC)

Thanks. Is this really not the French Dunkirk then? William M. Connolley 18:30, 28 January 2006 (UTC).

Eh... I'm not actually sure now. Some of the related sites one would want to see are actually in the Southern Netherlands, so Belgium would make more sense, but I can't seem to actually find such a city. I don't suppose they could have moved the border recently? Sigh... geography is not my specialty. Dragons flight 19:04, 28 January 2006 (UTC)

I expected my edit not to survive long. Yes it is the same as the french Dunkirk. Linguistically and historically Dunkirk was part of Flanders, it became french territory in 1662. Here is an authorative link to Belgian coastal geology [43]. Although Dunkirk is the type locality, the dunkirk deposits are wide spread thoughout the low countries: my house in The Hague is standing on a Dunkirk tidal gully. The Dunkirk deposits are intergrated in the recently defined lithostratigraphic unit Naalwijk formation[44]., which includes most marine postglacial deposits. Moerner (yes William, him again! :-D ) identified Dunkirk episodes in Sri Lanka and the Maldives. Here is part of Moerners eustatic sea curve, which was accepted as authoritative in a presentation by the director of the dutch sea institute at the Dutch Met office KNMI[45]. Woodroffe and Horton give a thorough evaluation of the Holocene sea-level changes in the Indo-Pacific[46], strangely they don't refer to the work of Moerner on Sri Lanka and the Maldives, although there is a South African curve from Compton (fig 6 on page 12) which has a similar form. The IPCC conclusion reads: Holocene sea level variations have a maximum amplitude of 30 to 50 cm, which is larger than the recent rise since 1850 of only 15 cm. Speculation on future sea level must be indicated as such, given the huge uncertainty in the SRES scenarios (but that is a different topic). Finally I would like to advertise the PhD work of Dr. Kira van Onselen (K.I. van Onselen, The influence of data quality on the detectability of sea-level height variations, Publications on Geodesy 49, Delft, 2000. 220 pages. ISBN 90 6123 273 1.) who concluded that it takes thirty years to establish a trend due to the high noise level. The Topex Poseidon conclusions of an observed accellerated sea level rise, using an altogether different observation method and sampling different parts of the ocean surface are therefore very premature. Hans Erren 22:02, 28 January 2006 (UTC)

Greenland Ice sheet melting

I've rewritten a little of the section, reflecing current knowledge. Previously, it was believed that melting would be slow, probably occur on a millenium scale or more. Things have changed in very recent years. The most recent major publication discussing the subject is the 2004 Arctic Climate Impact Assessment, which says in the summary that the melting will occur 'over centuries'. Elsewhere in various public media articles (see linked) it's mentioned that researchers now believe that it may occur in much less than a millennium. Jens Nielsen 21:23, 21 February 2006 (UTC)

I still don't believe this, and I wish you would cite your sources more precisely. Looking at http://amap.no/acia/Highlights.pdf I find:

...sea level is projected to rise 10 to 90 centimeters this century...

This century yes, but we're talking about long-term changes here. Have a look at Chapter 6 of the scientific report. I'll quote it sometime i get around to it.

Errm, if they are taking their line in the summary from the TAR, it would be odd to take a different line elsewhere. Note that you directed me to the summary before, now to chapter 6. William M. Connolley 22:25, 21 February 2006 (UTC)

OK, looked at chapter 6, can't see it. How about you actually quote the relevant text, or perhaps provide a page number - the thing is 100's of pages, "see chapter 6" is deplorably vague. William M. Connolley 22:33, 21 February 2006 (UTC).

this is exactly from the TAR, not new. Where do you see this "new" stuff coming from? Please provide some actual refs, not a vague "see linked". William M. Connolley 22:01, 21 February 2006 (UTC).

Please take the trouble to read the links i provided in this article, or those in the Greenland Ice Sheet. If still not satisfied, I'll look up again. Jens Nielsen 22:11, 21 February 2006 (UTC)

I'd appreciate it if you could provide just *one* reliable one, here. William M. Connolley 22:25, 21 February 2006 (UTC).

Second that. Mostlyharmless 03:05, 22 February 2006 (UTC)

Fair enough, I'll add some info. First off, I see you like to have quotes to specific scientific articles. It's a witness of high standards, but I think it fair enough (often even better) to quote major reports or reviews broaching the subject. That's why I picked the ACIA, to me appearing the best source pick until AR4 comes. From there, I think it is reasonable to expect scientists to look up the specific research behind those findings themselves, which is why I have not been eager to do that myself. But of course, the burden is on thge wikipedia editor (me) to quote them properly.

The 'most recent' findings I referred to were roughly these, from research by Eric Rignot et. al. It's from a BBC article, as I do not have free access to the Science Magazine article where the research was published.

Previous estimates suggested it would take many hundreds of years for the Greenland ice sheet to melt completely. The new data will cut this timescale, but by how much is uncertain.[47]

The ACIA says the following (summary, pdf page 39, section "The importance of thresholds"

"The onset of the long-term melting of the Greenland Ice Sheet is an example of a threshold that is likely to be crossed this century. Climate models project that local warming in Greenland will exceed 3 degrees Celcius during this century. Ice sheet models project that a warming of that magnitude would initiate the long-term melting of the Greenland ice sheet. Even if climatic conditions then stabilized, an increase of this magnitude is projected to lead eventually (over centuries) to a virtually complete melting of the Greenland Ice sheet, resulting in a global sea level rise of about seven meters"

I hope this meets the gentlemen's standards for a reliable source/quote.

Though the first one is only a newspaper article, these two together seems to me good enough support for the 'centuries' statement, though I am open to further comments and won't pretend to know all research on the subject. If any of you have access to Science magazine, please get a quote from the full text of the relevant paper. As for the chapter 6 of the ACIA scientific report, I had only a brief look at it, but I assume that the matter is explored in more detail there. I will look into it later, or leave you to do so in the meanwhile. Jens Nielsen 16:15, 22 February 2006 (UTC)

The BBC one is useless. This is generic journalism, and as usual is poor for science. It was thought the entire Greenland ice sheet could melt in about 1,000 years... is wrong for a start; and the text doesn't get any better. The ACIA quote is very vague too: it says "over centuries" but not how many. Melting "over centuries" is *not* the same as *several centuries*. Also, I see no support for this from chapter 6. As you said From there, I think it is reasonable to expect scientists to look up the specific research behind those findings themselves, which is why I have not been eager to do that myself.: anything in the ACIA summary should be backed up by the appropriate chapter, but its not. The appropriate pages from chapter 6 would be 207 and 233, but there is nothing there, except ACIA quoting IPCC. I conclude that ACIA has no new results past IPCC.

So, onto some real science. Greve, R., 2000: On the response of the Greenland ice sheet to greenhouse climate change. Clim. Change, 18 46, 283-289. got substantial retreat within 1000 years for seasonally uniform warmings > 3 oC; Ridley, J.K., Huybrechts, P., Gregory, J.M. and Lowe, J.A. Elimination of the Greenland ice sheet in a high CO2 climate. Journal of Climate, 18, 3409–3427, 2005 with constant 4×CO2 in HadCM3 coupled to a Greenland ice sheet model: after 3000 years the warming reached 18°C and only 4% of the original volume remained. Thats 4*CO2, sfc warming of 18 oC, and *still* not all gone in 3kyr. More about that at http://www.metoffice.gov.uk/corporate/pressoffice/adcc/BookCh4Jan2006.pdf. I'm restoring "millenia". William M. Connolley 16:51, 22 February 2006 (UTC)

OK, I'll accept your correction, as neither I could find any substantiation of the statement from the scientific background report, and of course I still don't have access to the new science magazine article. However, I suspect that there must be something to the claim. I find it straining my credulity that not just the BBC (including many others) but also and especially a reputed major publication would be off by an order of magnitude on such an important issue. Whoever has access to the full articles of Science magazine please check if a claim to a less-than-millennium melt is supported in the article? Jens Nielsen 21:56, 22 February 2006 (UTC)

I can confirm that neither the science article in Science, nor the accompanying news article in the same issue address the issue of melt over the next 1000 years. I'm including quotations from each that come the closest to addressing the issue:

Changes in the Velocity Structure of the Greenland Ice Sheet, Rignot and Kanagaratnamin (doi:10.1126/science.1121381):

If more glaciers accelerate farther north, especially along the west coast, the mass loss from Greenland will continue to increase well above predictions.

The Greenland Ice Sheet and Global Sea-Level Rise (doi:10.1126/science.1124190):

In a warming world, it is likely that the contribution to sea-level rise from Greenland is set to grow further, assuming that the observed acceleration in outlet-glacier velocities is sustained, with possible increases in precipitation providing the only prospect of short-term amelioration.

In interviews Rignot has stated that he believes that the estimates for time required for total melt will have to be revised, but no models have been published to confirm his conjecture.Leuliett 23:42, 22 February 2006 (UTC)

Thanks. My impression (but I admit I cannot substantiate this, so I will make no attempt to add it!) is that its pretty well impossible to deglaciate Greenalnd via increased glacier flow on any kind of plausible timescale - the dynamics just don't allow it. William M. Connolley 00:05, 23 February 2006 (UTC)

I'll inquire a bit further, as I'm still not quite satisfied. If what Rignot above says is right, we could be talking about centuries rather than millennia. Perhaps we'll have to wait a year or two, see if the claim solidifies. Jens Nielsen 07:59, 23 February 2006 (UTC)

Greenland has a volume of ~2.6*10⁶ km³, the present mass balance deficit is 220 km³ per year (Rignot and Kanagaratnamin 2006). At which rate it would take ~10,000 years to deglaciate. To do it in under 1000 years, would require sustained rates at least an order of magnitude greater than present. Maybe that's possible, but it is by no means obvious. For what it is worth though James Hansen is also of the opinion that the ability for Greenland to change is being underestimated. Dragons flight 08:19, 23 February 2006 (UTC)

(Rignot and Kanagaratnamin 2006).apparently conclude that the net current mass/ice balance is much lower than hitherto thought (net -96 km3/yr in 1996 to -220 km3/yr in 2005 versus -44 Gt/yr in IPCC TAR[48]). If so, the future melting models should be adjusted accordingly, which apparently has not happened. That it would 'only' melt in 10k years at current speed is not very informative, as we know it will accelerate.Jens Nielsen 09:42, 23 February 2006 (UTC)

Non-technical intro

The first 100 to 1,000 words of this article need to be simplified or condensed. The main points are not clear:

• How much has sea level risen throughout measurable geological history?
• What do scientists think caused this rise? Glaciers melting, maybe?

As for recent sea level rise, there's a debate over whether it's

1. glaciers are still melting, as a natural recovery from the last ice age; or,
2. glaciers are melting much faster, due to human-cause global warming

Should we treat the global warming angle as generally undisputed or largely "up in the air"? --Uncle Ed 19:29, 23 February 2006 (UTC)

Hi Ed. See-also the "Split the article?" section up above. William M. Connolley 20:00, 23 February 2006 (UTC).

Dispute about rate and cause

Cut from end of intro:

This change may be the first signs of the effect of global warming on sea level, which is predicted to cause significant rises in sea level over the course of the twenty-first century.

I also added this:

Sea level has been rising at a rate of 1.8 mm per year for the past 8,000 years; the IPCC notes that "No significant acceleration in the rate of sea level rise during the 20th century has been detected." [49]

I think we need a table of various claims. Who says the rate has not accelerated (IPCC), and who says that it has? --Uncle Ed 19:42, 30 May 2006 (UTC)

Well, since that was from SEPP it was always likely to be wrong, and indeed... it is wrong. So I took it out again. Just look at the handy graph William M. Connolley 20:52, 31 May 2006 (UTC)

Here's a direct quote from a United Nations Intergovernmental Panel on Climate Change report, or the "TAR" as you may prefer:

• Based on the very few long tide-gauge records, the average rate of sea level rise has been larger during the 20th century than during the 19th century. No significant acceleration in the rate of sea level rise during the 20th century has been detected. [50]

Perhaps the quote should go back in. --Uncle Ed 15:00, 9 June 2006 (UTC)

The no-acc quote is really from IPCC. Its maybe a bit out of date now, but still, it is from the gospel William M. Connolley 16:35, 9 June 2006 (UTC)

Intro

Cut from intro:

From 3,000 years ago to the start of the 19th century sea level was almost constant, rising at 0.1 to 0.2 mm/yr; since 1900 the level has risen at 1 to 3 mm/yr [51]; since 1992 satellite altimetry from TOPEX/Poseidon indicates a rate of about 3 mm/yr [52]. This change may be the first signs of the effect of global warming on sea level, which is predicted to cause significant rises in sea level over the course of the twenty-first century.

This stuff sets a pro-GW tone for the article. Is the purpose of this article to prove that the Global warming theory is true?

And how can the lay reader (or even the technically adept, mathematically-competent reader) get pointed to evidence that the level was almost steady but started shooting up again? A graph showing this would be nice. --Uncle Ed 14:56, 9 June 2006 (UTC)

You'd need the last 3kyr only, I guess

I don't see why you want to gut the intro. It isn't pro-GW, so I've put it back William M. Connolley 16:33, 9 June 2006 (UTC)

This is a bit confusing

If all glaciers and ice caps melt, the projected rise in sea-level will be around 0.5 m. If the melting includes the Greenland and Antarctic ice sheets (both of which contain ice above sea level), then the rise is a more drastic 68.8 m.

Perhaps it should read, If all glaciers and ice caps with the exception of the Greenland and Antarctic ice sheets melt, the projected rise in sea-level will be around 0.5 m.

Richard Bruce 16:39, 18 July 2006 (UTC)

I don't think the clarity is a problem, but I do think the figures are wrong. See my post "Millimeters, not meters!" below. —The preceding unsigned comment was added by 70.100.60.2 (talk) 01:21, 3 February 2007 (UTC).

What do scientists say?

Anyone seen this journal article yet?

• Two processes are involved: an increase of the mass of water in the oceans (the eustatic component), derived largely from the melting of ice on land, and an increase of the volume of the ocean without change in mass (the steric component), largely caused by the thermal expansion of ocean water.
• Neither of these components is understood fully, and observations are not sufficient yet to develop a precise assessment of the causes of present-day sea-level rise let alone a projection of future rise. In fact many of the analyses produce conflicting results.
• Also, there are a number of terrestrial processes such as ground-water depletion, land-use changes, and reservoir construction that have some effect on sea level. The IPCC 2001 study points out that these terrestrial effects might be appreciable and assigns very wide error limits; however, values near these extremes require the juxtaposition of very unlikely circumstances.(PNAS | May 14, 2002 | vol. 99 | no. 10 | 6524-6526)

I hope the article distinguishes between mass and volume, in a way that's clear for the average reader.

Also, I wonder if the article should assert that sea level rise is a sign of the "truth" of the Global Warming theory. --Uncle Ed 17:53, 25 January 2007 (UTC)

Millimeters, not meters!

"If all glaciers and ice caps melt, the projected rise in sea level will be around 0.5 m. If the melting includes the Greenland and Antarctic ice sheets (both of which contain ice above sea level), then the rise is a more drastic 68.8 m." As near as I can tell, this is a misunderstanding of the cited source, http://www.grida.no/climate/ipcc_tar/wg1/412.htm#tab113. No units are given (bad scientists!) but I think they're mm. I am correcting the article but noting this here in case I am wrong. —The preceding unsigned comment was added by 70.100.60.2 (talk) 01:19, 3 February 2007 (UTC).

No thats not correct - table 11.3 is in meters. --Kim D. Petersen 20:24, 4 February 2007 (UTC)

Word choices

I have a concern (a stylistic one but that impacts clarity) about word choice, that I assume may be a difference between British and American English: Rracecarr added the following changes (bolded):

Ice shelves float on the surface of the sea and, if they melt, to first order they do not change sea level. Likewise, the melting of the northern polar ice cap which is composed of floating pack ice would not significantly contribute to rising sea levels. Because they are fresh, however, their melting would cause a very small increase in sea levels, so small that it is generally neglected. It can however be argued that if ice shelves melt it is a precursor to the melting of ice sheets on Greenland and Antarctica.

To American ears, I'm not sure what "to first order" means -- is there some other choice of phrase that can explain what is meant? And similarly, the change made from "freshwater" to "fresh" sounds odd. "Freshwater" makes more sense to someone Stateside. Cheers, Arjuna 22:22, 3 February 2007 (UTC)

TFO could be replaced with "make very little change" William M. Connolley 22:26, 3 February 2007 (UTC)

Could we get maps for this article?

I think it'd be really interesting to see what the world would look like if all the ice on the polar caps melted. It'd be a rise of about 60m, right? That'd totally change the landscape of the world! Also, perhaps a map could be included of what the world looked like before the 130m rise after the most recent ice age? That'd be ace. Does anyone now how we could do this? A special map programme perhaps? — Jack · talk · 06:05, Sunday, 11 March 2007

Here's a nice Java applet that will do just what you ask. Set the sea level rise (or fall) and see what the world looks like: Effect of a change in sea level on worldwide topography Raymond Arritt 06:18, 11 March 2007 (UTC)

Wow, that's pretty funky. Thanks for the link, I'll remember that one. Only, water appears to be appearing from no-where when the sea level rises, surely it'd need a route from the poles to the new location? Like the Hungarian basin is surrounded by mountains at a min height of several hundred meters, yet seems to fill up. The dead sea is below sea level, yet us currently emptying... I guess it's purely a topography-based application. Thanks anyway, it's better than my paint-based attempt! — Jack · talk · 07:32, Sunday, 11 March 2007

Cut/Paste Typo or Error

I found what appears to be some kind of typo or cut/paste operation gone bad, maybe I'm missing something. It says, "Frozen Ground 28, December 2004, has a very significant map of permafrost affected areas in the Arctic." I know this is a minor thing, but I obsess. Somebody fix it! Jawshoeaw 08:23, 15 July 2007 (UTC)Jawshoeaw

Structure

I think this entire thing needs restructuring William M. Connolley 15:37, 5 September 2007 (UTC)

Huge Misinterpretation

I don't know how you people go about this, but it's this bit:

If small glaciers and ice caps on the margins of Greenland and the Antarctic Peninsula melt, the projected rise in sea level will be around 0.5 m. Melting of the Greenland ice sheet would produce 7.2 m of sea level rise, and melting of the Antarctic ice sheet would produce 61.1 m of sea level rise.[3] The collapse of the grounded interior reservoir of the West Antarctic Ice Sheet would raise sea level by 5-6 m.[4]

Whom ever put those down wildly misinterpreted their source.

http://www.grida.no/climate/ipcc_tar/wg1/412.htm#tab113

I'm not sure what the ^c behind 7.2^c 61.1^c these numbers mean's but It definatly doesn't imply meters. As in if those Ice sheets melt the earth sea levels will not rise 242 feet. That table is on thermal expansion not liquefaction as far as I can tell. —Preceding unsigned comment added by 68.49.145.173 (talk) 19:54, 9 September 2007 (UTC)

Nope, its you that have misunderstood. Gr is about 7m; Ant 60-odd. The numbers from the IPCC are the Gr/Ant contribution to 2100, not for meltin the entire sheet William M. Connolley 20:51, 9 September 2007 (UTC)

Rough calc for Greenland ((ice mass * ice density)/water surface) gives around 7.2 meters: ((2850000.0 km³*0.92)/361126400km²), so i'd say it sounds reasonably correct. --Kim D. Petersen 21:06, 9 September 2007 (UTC)

Article name: Rise vs. changes

What is the subject of this article: Sea level rise or sea level change? Making it only about rises seems unecessarily specific, while changes is more broad and basically reflects its current content. Is the current name preferable, or would moving it to sea level change or changes in sea level be more appropriate? Sea level rise is probably more likely to be looked up, and is quite topical, though it only reflects one half of the story. See also #Merged with Sea level change, #Split the article? and #Breaking up this article. Richard001 01:09, 15 September 2007 (UTC)

Satellite in the Intro

Satellites are cool - but should not be mentioned in the intro paragraph. TOPEX/POSEIDON was a short lived experimental machine with known instrument problems, calibrated from land tidal records, with large uncertainty/innacuracies, and it more-or-less simply confirms the existing U.S. tidal guage data - the intro should be cleaned up, should describe that it's summarising USA records (or else mention the rest of the globe), and should generally be kept accurate. The satellite stuff should be further down - probably in the "U.S." section. Anyone agree/disagree ? If so/not - your reasoning? —Preceding unsigned comment added by 203.206.137.129 (talk) 10:14, 1 October 2007 (UTC)

Um. I don't see anything to suggest that the intro is talking about US records - what makes you say that? Its mostly sourced to IPCC, which is global. Your opinions of TOPEX/P would need some substantiating before we move stuff based on them - again, the info is quoted from IPCC, which isn't Gospel but is to be preferred to an unknown opinion William M. Connolley 19:01, 2 October 2007 (UTC)

Damn I wish I'd bookmarked that TOPEX/POSEIDON inquest. When the IPCC 2007 / AR4 report finally comes out, I'll hunt down the TOPEX accuracy stuff too, and we can revisit this idea. The old 2001 IPCC info quoted in the intro also says this: "There is no evidence for any acceleration of sea level rise in data from the 20th century data alone." which makes me think their definition of "20th century warming" needs better explanation - hopefully their 2007 report will be clearer. 203.206.137.129 15:08, 8 October 2007 (UTC)

Erm? The IPCC 2007 AR4 report is out. --Kim D. Petersen 16:14, 8 October 2007 (UTC)

Drafts maybe? No doubt the 2500+ reviewers have probably leaked pre-finalized or possibly edited versions... The web site says "is coming out", and "is currently finalizing" and mentions Nov 07 - http://www.ipcc.ch/

Future sea-level rise table

The projected rise due to ongoing adjustment to the end of the last ice age is uniquely given in metres, not millimetres. As far as I can tell (TAR WG1 p. 423, p. 430), the given figures are correct. WG1: "We therefore take the ongoing contribution of the ice sheets to sea level rise in the 20th and 21st centuries in response to earlier climate change as 0.0 to 0.5 mm/yr. This is additional to the effect of 20th century and future climate change." I can't find the total component used but multiplying 0.5 mm by 110 (1990-2100) gives 55 mm. I'd change the current "0 to 0.05 m" to "0 to 55 mm" but I'm not wholly confident that I'm doing the right thing. (Simply mutliplying by 110 seems a bit too ... well, simple.) Can someone with a firm grasp of the subject confirm (or otherwise) that 55 mm is the right number? Vinny Burgoo 11:32, 4 October 2007 (UTC)

Greenland etc and ice sheets

The entire article is messy and repeating redundant info - eg "Glaciers and ice caps" and "Polar ice" and "Greenland contribution" and the table "Intergovernmental Panel on Climate Change results" etc...

A serious tidy-up is needed :-)

203.206.137.129 16:18, 8 October 2007 (UTC)