2011-03-29 07:25:41New paper finding no acceleration in sea level rise
John Cook

john@skepticalscience...
124.185.238.238

I'm sure this one will be coming up on the denialosphere. I've added it to our list of peer-reviewed papers under the Skeptic column:

Sea-Level Acceleration Based on U.S. Tide Gauges and Extensions of Previous Global-Gauge Analyses

Without sea-level acceleration, the 20th-century sea-level trend of 1.7 mm/y would produce a rise of only approximately 0.15 m from 2010 to 2100; therefore, sea-level acceleration is a critical component of projected sea-level rise. To determine this acceleration, we analyze monthly-averaged records for 57 U.S. tide gauges in the Permanent Service for Mean Sea Level (PSMSL) data base that have lengths of 60–156 years. Least-squares quadratic analysis of each of the 57 records are performed to quantify accelerations, and 25 gauge records having data spanning from 1930 to 2010 are analyzed. In both cases we obtain small average sea-level decelerations. To compare these results with worldwide data, we extend the analysis of Douglas (1992) by an additional 25 years and analyze revised data of Church and White (2006) from 1930 to 2007 and also obtain small sea-level decelerations similar to those we obtain from U.S. gauge records.

The conclusion is more blunt:

Our analyses do not indicate acceleration in sea level in U.S. tide gauge records during the 20th century. Instead, for each time period we consider, the records show small decelerations that are consistent with a number of earlier studies of worldwide-gauge records. The decelerations that we obtain are opposite in sign and one to two orders of magnitude less than the +0.07 to +0.28 mm/y2 accelerations that are required to reach sea levels predicted for 2100 by Vermeer and Rahmsdorf (2009), Jevrejeva, Moore, and Grinsted (2010), and Grinsted, Moore, and Jevrejeva (2010). Bindoff et al. (2007) note an increase in worldwide temperature from 1906 to 2005 of 0.74°C. It is essential that investigations continue to address why this worldwide-temperature increase has not produced acceleration of global sea level over the past 100 years, and indeed why global sea level has possibly decelerated for at least the last 80 years.

2011-03-29 07:35:21Feedback on this
John Cook

john@skepticalscience...
124.185.238.238

Some correspondance among scientists I've observed on this paper:

The satellite data from altimeters are the only data that give global sea level.  Prior to 1992 there were only spot values of relative sea level at islands and coastal stations.  As shown in Fig 1 of that paper there is a clear increase in slope after about 1930 vs before but the number of stations are few.  The recent lobal record gas consistently shown rates of about 3 mm/yr which is clearly larger than the 1.7 mm/yr of the station data.

The model these authors use is quite inappropriate mathematically.  They fit a linear term and then a nonlinear term to the data, and such a model implies changes before and after each record that are clearly impossible and silly.  It is also extremely sensitive to end effects: when the record starts and finishes. The method is useless for addressing the task at hand and overlooks the obvious.

And

I'm told from someone who works in this area that there are deep problems w/ this study. the 1930 beginning date was cherry-picked beyond belief. There is a rebuttal already in the works.

2011-03-29 07:42:09Grrr
oslo

borchinfolab@gmail...
90.149.33.182

I've seen this in various media in Norway today (or yesterday), with the regular promulgation (correct word I hope) from the denialsphere.

How can the authors conclude on global sea level rise from observations in USA?

Perhaps I'm not surprised.

Sea level rise map:

http://climate.nasa.gov/news/index.cfm?FuseAction=ShowNews&NewsID=16

2011-03-29 07:43:05WUWT
dana1981
Dana Nuccitelli
dana1981@yahoo...
64.129.227.4

Already posted on WUWT

As one of the quotes John provided noted, how can you possibly say no acceleration when the current rise (3.4 mm/yr) is twice the average 20th century rise (1.7 mm/yr)?

2011-03-29 07:54:07
Albatross
Julian Brimelow
stomatalaperture@gmail...
199.126.232.206

Some flags:

1)  Until today I ahve nevere heard of the journal (JCR), but admittably it is not my field.

2) One of the authors is "Professor Emeritus"-- sad to say, but many profs who go emeritus, also tend to be a little on the bizarre side.  There is even an expression "going emeritus"-- and it is not meant to be flattering.

 

2011-03-29 08:56:27Public misunderstanding of rates of change.
logicman

logicman_alf@yahoo.co...
86.148.171.99

It is my experience that most ordinary members of the public equate any decline in a rate of growth to a decline in value.  If some people are told that sea level rise acceleration is declining they will take this to mean that sea level is declining.

 

An example of this inability to understand rates of change can be seen in politics: Edward Heath's promise to cut the rate of inflation was repeated in the media as a promise to cut prices.

 

I think the following is relevant to the discussion:

 

P. J. Watson (2011) Is There Evidence Yet of Acceleration in Mean Sea Level Rise around Mainland Australia?. Journal of Coastal Research: Volume 27, Issue 2: pp. 368 – 377.

2011-03-29 09:12:00Resources on sea level rise
oslo

borchinfolab@gmail...
90.149.33.182

Did this graph escape Sks attention?

Or this site?

Or this report?

2011-03-29 16:01:04
Rob Painting
Rob
paintingskeri@vodafone.co...
118.93.208.132

Gotta agree with Oslo, are these guys stupid?, comparing USA trends to studies of global trends?.  If SLR were homogeneous they might have a point but..........

2011-03-30 02:40:46
oslo

borchinfolab@gmail...
90.149.33.182

There is a few papers on why the SLR is not homogenous which I have browsed through.

Also this article at e360 is interesting.

I particulary enjoy this presentation on YouTube (one hour) - which discusses the subject:

In Search of Lost Time: Ancient Eclipses, Roman Fish Tanks and the Enigma of Global Sea Level Rise
http://www.youtube.com/watch?v=GdfTUdU9x-k

2011-03-30 06:12:25Comments from Josh Willis
John Cook

john@skepticalscience...
124.185.238.238

Ray Weymann (from CSRRT) forwarded this critique from Josh Willis:

> I've had a look at this Houston & Dean paper and I do have a few
> concerns with it.  My biggest concern is that this paper might be
> interpreted too broadly as meaning that there is no evidence for
> acceleration in the rate of global sea level rise over the last 100+
> years.  Also, I think it should definitely not be used to imply
> anything about future rates of sea level rise, even though they
> discuss future rates at some length.
>
> I think it is widely known that individual tide gauges have enormous
> decadal variations (as much as 10 cm).  We also know from altimeter
> observations that much of these decadal variations average out when
> taking the global mean.  This means that it is very difficult to
> estimate the rate of globally averaged sea level rise from tide gauges
> alone.  Much less to do so with sufficient accuracy to detect
> something as subtle as an acceleration.  I also note that for many of
> the records used by Houston & Dean that were signficantly longer than
> 100 years, accelerations were usually positive when the entire record
> was used (see their table 1).
>
> In order to address this sampling issue, I think great care is needed
> in choosing geographic averages that are representative of the global
> mean (as did Merrified and Merrifield, 2009), or fitting EOFs (as did
> Church and White, 2006).  Even then, I think you need to be careful to
> have the longest record possible if you are looking for an
> acceleration.  For example the Church and White curve would look less
> like an acceleration without the pre-1900 data.  The short answer is,
> this is a difficult signal to detect in the tide gauges alone.  And to
> do so, it is important to use the longest records possible, which was
> not always done in this paper.
>
> I am also a bit concerned by the discussion of altimeter errors in the
> paper.  I find it surprising that Houston & Dean mention the list of
> potential error sources in altimetry documented by Ablain et al
> (2009), but failed to actually quote the uncertainty estimated by
> Ablain in light of all these errors, namely +/- 0.6 mm/yr.  So despite
> these uncertainties, the 16-year rate from altimetry is 3.1
> +/- 0.6 mm/yr, which is obviously significantly higher than the
> accepted 1.7-1.8 mm/yr average rate over the 20th century.  The
> authors suggest large decadal variations in the rate of rise over the
> course of the last century in Figure 6, but getting the decadal rate
> of globally-averaged sea level rise from tide gauges alone is even
> harder than getting the acceleration (with all due respect to Simon
> Holgate).
>
> So, while this is an interesting paper, I think the evidence for a
> deceleration in the rate of GLOBALLY AVERAGED sea level rise is not
> all that strong.
>
> All the best,
> Josh
>
> ps. - feel free to pass these comments along to interested parties. 

I think this would be worth a post.

2011-03-30 06:16:55*Definitely* worth a post
John Cook

john@skepticalscience...
124.185.238.238

It's gone mainstream:

http://www.washingtontimes.com/news/2011/mar/28/al-gores-seawater-swindle/

I've added a new argument to the database to target this specifically: "Sea level rise is decelerating". So if anyone wants to write a rebuttal to this, it's all yours!

2011-03-30 08:52:46Okay from Josh Willis to repost
John Cook

john@skepticalscience...
124.185.238.238

Josh has granted an okay to repost any of his quote. You don't need to necessarily - you could use it as a guide to construct your own rebuttal - but if anyone wants to tackle this argument, the option is there to excerpt Josh's words.

2011-03-30 10:42:00Quote from Kevin Trenberth email
John Cook

john@skepticalscience...
124.185.238.238

Haven't received okay to repost this publicly though. UPDATE: Kevin has given ok for this quote to be used if required:

The satellite data from altimeters are the only data that give global sea level.  Prior to 1992 there were only spot values of relative sea level at islands and coastal stations.  As shown in Fig 1 of that paper there is a clear increase in slope after about 1930 versus before but the number of stations are few.  The recent global record has consistently shown rates of about 3 mm/yr which is clearly larger than the 1.7 mm/yr of the station data.

The model these authors use is quite inappropriate mathematically.  They fit a linear term and then a nonlinear term to the data, and such a model implies changes before and after each record that are clearly impossible and silly.  It is also extremely sensitive to end effects: when the record starts and finishes.

2011-03-30 21:40:08Church & White 2011
oslo

borchinfolab@gmail...
90.149.33.182

Here's a plot of data from Church & White 2011 (upcomming article).

The data is available here.

Ground level observation seems to verify satelite data. What a surprise.

See the incline anyone?

2011-03-30 21:54:28
Rob Painting
Rob
paintingskeri@vodafone.co...
118.93.204.120

You gonna write this one up Oslo?.

2011-03-30 22:01:07
oslo

borchinfolab@gmail...
90.149.33.182

Sorry, I don't think I'll qualify :-(

Trying to finish the live chat program, which have rested a few days.

The plots I referenced was made available by dumskalle (means idiot in norwegian).

2011-03-31 00:35:36Great idea?
oslo

borchinfolab@gmail...
90.149.33.182

How about making an application where you have a global map, where you can pick and choose the areas of observation on SLR - based on the data from Church & White? I guess the data include lat/long which can be estrapolated on a map.

Would this be a cool app?

It would clearly show why this new study is wrong, and why using limited observations lead to skewed result.

Update: I checked the data, and it does not contain individual station data (just a description of which stations are used) - I guess the individual station data must be retrieved from here.

2011-03-31 05:47:01
Rob Painting
Rob
paintingskeri@vodafone.co...
118.93.203.226

So if you clicked on a tide guage, it would show the graph of sea level variation for that site? Good in theory, but last time I looked at a few of the station data, some of them are a real mess.

Your idea sounds a lot better than the clunky GLOSS set up.   

2011-03-31 06:12:48
oslo

borchinfolab@gmail...
90.149.33.182

My idea was that you could select an area of interest (a square selector box on a global map perhaps), and then have a plot which reflects the SLR in the area of interest.

The station data would need to be hand picked to chose stations who provide contineous data (I guess the station list provided by Church & White would do).

I would need the GIA (Glacial Isostatic Adjustment) for each site which I havn't found yet.

So if the station data are good, and if I have the GIA correct - this might be possible in technical terms.

2011-04-01 00:51:53
MarkR
Mark Richardson
m.t.richardson2@gmail...
83.150.146.79

Looks like Tamino flattened it at open mind.

 

A quick skim and it looks like pretty shit work. I expect there to be a publish rebuttal and probably a correction/retraction if the journal is any good.

2011-04-01 00:56:24
Paul D

chillcast@googlemail...
82.18.130.183

That reminds me, the last years worth of UK tidal gauge data should have been released about now.

2011-04-01 08:26:42
oslo

borchinfolab@gmail...
90.149.33.182

I think that Tamino was right on target with his comments.

He should add the map on SLR and its distribution globally - I'll make a comment on this at Tamino.

Found a better map on this yesterday, but now I can't refind it again :-(

I think Tamino is doing a very good contribution on many issues - reference his graphs all the time :-)

Someone at Sks could perhaps add a rebuttal on the lines provided by Tamino?

2011-04-01 17:25:21
Rob Painting
Rob
paintingskeri@vodafone.co...
118.92.65.213

"Someone at Sks could perhaps add a rebuttal on the lines provided by Tamino?"

Or ask him to re-post his rebuttal here. I nominate you (if John if amenable to the idea) 

2011-04-02 01:55:30
oslo

borchinfolab@gmail...
90.149.33.182

I'll be happy to ask, didn't find an e-mail address on his site, but I could of course add a comment on this.

I would advise to have a SLR map added to the article which show that the result from this study is actually what you would expect from the uneven distribution of SLR.

OK by you John? - perhaps you even have his mail address?

2011-04-02 03:03:52good idea
dana1981
Dana Nuccitelli
dana1981@yahoo...
64.129.227.4

I think it's a great idea to see if we can get tamino to do a guest post on the issue.  I'm pretty sure John will be on board too.  The more collaboration, the better.

2011-04-02 08:26:28I'll email Tamino
John Cook

john@skepticalscience...
124.185.238.238
I've got his email so will ask him today.
2011-04-03 00:34:19
oslo

borchinfolab@gmail...
90.149.33.182

Good progress on this John - a very important issue in my opinion, which SkS should cover - I'll write a rebuttal my self if Tamino "refuses" to do a cross post :-)

2011-04-03 21:04:41GIA
oslo

borchinfolab@gmail...
90.149.33.182

Just had a look at the Church and White data again.

The GIA (Glacial Isostatic Adjustments) and lat/long are present in the station list provided with the data.

So it should be possible to make a station list preferably on a map, and then to choose the stations you wan't and then draw a graph based on the selected stations. Not sure how usefult this ap would be, but it could be a bit interesting perhaps?