More Monkey Business with the Mean Sea Level

[IanC]

The Inconvenient Skeptic » More Monkey Business with the Mean Sea Level

The University of Colorado Sea Level Research Group updated their data in July, but oddly enough the new data was only available through mid-April. In the past these updates have tended to bring the Mean Sea Level (MSL) up to date. That is the first oddity in this update, but it is also the most trivial. This update also reversed the isostatic adjustment that they put in earlier this year. I covered the isostatic adjustment here and the previous update here. In essence they intentionally inserted a 0.25 mm/yr trend into the MSL. The result of such a ‘update’ is that it maintained the status quo 3.1 mm/yr that they have been advocating. That trend has ceased over the past 5 years.

The latest update eliminated the isostatic adjustment, but added in the following new one:

Replaced classical GDR Inverted Barometer correction on all missions with improved AVISO Dynamic Atmopshere Correction (DAC) that combines MOG2D high frequency and inverted barometer low frequency signals (Pascual et al., 2008)

They have also made previous versions of the data unavailable. Fortunately I am a pack rat and have all the original data. If the isostatic adjustment was overboard, this one is really over the top.

This chart shows that there is a 3.2 mm/yr trend in the MSL since 1993.

The first obvious difference in this data from previous data is a shift of ~10 mm for the data from 1993. There is absolutely no reason to shift data that is almost 20 years old, but they did. This chart shows the data that was available 1 year ago and the latest data. Both of them retain the seasonal signal.

The difference for the available data in 2010 is 14.66 mm difference. What started out as a 10mm shift is most recently an ~15mm shift in the most recent MSL. The trend in the difference is 0.18 mm/yr for the smoothed data. The funny thing is, even with all of this monkey business, the sea level trend for the past few years is dropping. Even with an added trend, a step function shift in 2004 and the overall shift since 1993, the trend for the past 5 years is only 2.0 mm/yr.

UCAR's last bodge involving openly admitted GIA didnt go so well politically or in the media. I wonder if they will be quite as open about their 'adjustments' this time.

 

[Old Rocks]

Note that the measured line goes up and down, but the average is a curve that is increasing in the up direction.

How much is sea level rising?

How much is sea level rising?
Link to this pageThe skeptic argument...
Sea level rise is exaggerated
"We are told sea level is rising and will soon swamp all of our cities. Everybody knows that the Pacific island of Tuvalu is sinking. Around 1990 it became obvious the local tide-gauge did not agree - there was no evidence of 'sinking.' So scientists at Flinders University, Adelaide, set up new, modern, tide-gauges in 12 Pacific islands. Recently, the whole project was abandoned as there was no sign of a change in sea level at any of the 12 islands for the past 16 years." (Vincent Gray).

What the science says...
Select a level... Basic Intermediate
A variety of different measurements find steadily rising sea levels over the past century.


Sea level rises as ice on land melts and as warming ocean waters expand. Sea level rise mutually corroborates other evidence of global warming as well as being a threat to coastal habitation and environments.

The blue line in the graph below clearly shows sea level as rising, while the upward curve suggests sea level is rising faster as time goes on. The upward curve agrees with global temperature trends and with the accelerating melting of ice in Greenland and other places.

 

[Old Rocks]

http://www.safecoast.org/editor/databank/File/sea level rise implications denmark.pdf

Monitoring of sea levels

Sea level in Danish waters is monitored intensively and has been so for decades. In Denmark, systematic sea-level measurements were initiated by the Danish Meteorological Institute (DMI) in the 1880s. The DMI has obtained in this way sea-level time series over 100 years long from 10 separate stations throughout the country. Today, DMI operates 15 on-line stations, and their output is used for i.a. warnings of increased sea level and floods, based on a calculation of wind and air pressure (Aakjær, 2000). In recent decades, a series of water level monitors have been established for
various other purposes, and DMI is now responsible for the collection of data from about 40 stations. The results are available on the internet. Internationally, DMI collaborates with institutions, which are responsible for measurements
along the coast of the Baltic Sea. This collaboration takes place within the European organisation EuroGOOS (European component of Global Ocean Observing System), and will be expanded in the coming years. Along the west coast of Jutland, the Danish Coastal Authorities have operated 10 stations on line since the 1970s.

Recent trends

Due to vertical land movements, differential sea-level trends occur throughout Denmark. The 110 years time-series show a nearly continuous rise in mean sea level in The Wadden Sea of about 1 mm/year, whereas measurements on the northern and eastern part of the country indicate nearly constant sea levels. These trends have been reviewed with reference to climate changes by Duun-Christensen (1992). If past trends are projected, sea level is estimated to rise by 10 cm in the southern part of the country, and to fall slightly in the northwestern part. When the expected impacts of an
increased greenhouse effect are taken into account, a total global sea-level rise of 50 cm is estimated to produce rises of 18 to 46 cm in Denmark within the next century, mostly in the southern part of the country.

 

[IanC]

what, exactly, were you hoping people would get from your citations?

sea levels have been rising at roughly 2mm/yr for the last 100+ years. in the early 1990s satellite measurements came in and the rate immediately jumped to roughly3mm/yr. coincidence? maybe. the last 5 years have seen the rate drop to the usual 2mm/yr even though more and more effort seems to be used to keep the numbers artificially high. like the latest 'adjustments'.

why dont the scientists just use the data as collected? why are 20 year old measurements being 'corrected', a la Hansen?

Argo buoys came on line in 2003 and show little ocean heat content rise. surface temps have been flat since 1998, especially if you discount the special 'adjustments' that have been made. why arent the scientists just acknowledging the discrepancies between the models and real world data and moving forward? they seem to be personally invested in the results to the point that they are willing to disguise inconvenient data. THAT is my point. I would like to know the truth either way but every new distortion (always in the same direction) makes it more difficult to believe the next catastrophic prediction.

 

[Old Rocks]

Does ocean cooling prove global warming has ended?

Source: Levitus 2009

There are, however, disputes about the accuracy of Argo buoys and expendable measuring devices dropped into the sea, and the reporting of temperatures down to only 700 metres. How do scientists resolve these kind of disputes – bearing in mind that such disputes are the very stuff of science, the essence of true scepticism? One way is to find more data sources – different ways of measuring the phenomenon in dispute. By using results from seven different teams of scientists, all using different tools and methods, we are able to see a clear trend. And while there is variation between team results due to the differences in technique and measurement methods, one thing they all agree on: long term, temperatures are going up.

 

[Old Rocks]

ftp://ftp.nodc.noaa.gov/pub/data.nodc/woa/PUBLICATIONS/grlheat08.pdf

1] We provide estimates of the warming of the world ocean
for 1955–2008 based on historical data not previously
available, additional modern data, correcting for instrumental
biases of bathythermograph data, and correcting or excluding
some Argo float data. The strong interdecadal variability of
global ocean heat content reported previously by us is reduced
in magnitude but the linear trend in ocean heat content remain
similar to our earlier estimate. Citation: Levitus, S., J. I.
Antonov, T. P. Boyer, R. A. Locarnini, H. E. Garcia, and A. V.
Mishonov (2009), Global ocean heat content 1955–2008 in light of
recently revealed instrumentation problems, Geophys. Res. Lett., 36,
L07608, doi:10.1029/2008GL037155.

 

[IanC]

that certainly seems like a reasonable statement. I agree that temps have gone up, and that certain changes have happened because of it. I am less sure that they will continue to go up, even less sure that CO2 has anything more than a small part in it.

I am sure that measurements have been adjusted in ways that make it difficult to see what are actual changes and what are artifacts of methodologies. everyone uses the same sets of data. the historical data shouldnt change over and over again according to the whims of the data keepers, especially when the changes apparently are meant to serve a specific ideology.

 

[IanC]

a small update on sea levels.

The Inconvenient Skeptic » Sea Level Update: The oceans in decline.

nothing spectacular but there is a link to SkepticalScience that is interesting. they have posited that increased rainfall over land is the reason for the dip, but it doesnt seem to be realistically possible.