Wow no topic on Sea Level. Been a few discussions in the science of AGW thread and I hate multi topic threads that get confusing with multiple issues being discussed at the same time. So here are my responses to some issues from that thread:





A comparison of IPCC estimates with actual sea level rise shows these estimates to be too low:



Of course all climate scientists knew they would be too low, even the IPCC who stated that these projections did not include any allowance for dynamic effects of ice sheet melting. It is a bit misleading to talk about sea level rise being worse than expected as some have done recently. It is also misleading to compare rates of sea level rise that the IPCC predicted for the entire next century to sea level rise experienced recently as the IPCC have predicted sea level rise to speed up.

I'm not quite sure what you are getting at. It seems obvious that currents and temperature changes and whatever else (gravity effects) would be the explanation for why sea level rises at different rates at different places. Global warming would have nothing to do with this.

At the same time the average sea level is rising, and currents and temperature changes (that balance out) etc can have nothing to do with this rise.

At a guess are you trying to say that the sea level rise anomalies should circle in an anti-clockwise direction, but measurements show them doing something different so the measurements are wrong?

At different times within the PDO we would see variations in different zones of Australian Continent .

The Clockwise statement was in reference to a personal belief that there are return/feedbacks from ENSO through ITF and around thru to SAM , to put very simply . Of which , I beleive that it has an occurance on alternate PDO cycles . Or even a "Paradiddle Pattern " . ( Its a Drumming Rhythm ). Pretty far fetched , but I don't see anyone else with any idea ....

Mainly to answer your questions , I don't think they have a concise enough grasp of the forcings , and in this case The report that Spatch listed itself mentioned that it was early days ( and was hinting that they wanted more funding ) . [ Note they made a nearly a full page link to AGW - paerhaps to solve their funding problem ?! ]

Originally Posted By: Spatch

Go back to my original post where you'll find the links to the graphs. I don't have time right now to discuss your points.

http://forum.weatherzone.com.au/ubbthrea...es_a#Post987785




Re: Interesting news articles about AGW [Re: Spatch]
Southern Oracle
Weather Freak

Registered: 01/31/11
Loc: Southern Victoria
Originally Posted By: Spatch
For those still in denial about SLR, the pictures say it all...




http://www.bom.gov.au/ntc/IDO60202/IDO60202.2010.pdf



http://www.aviso.oceanobs.com/en/news/ocean-indicators/mean-sea-level/products-images/



So you couldn't summarise that .....

So Figure 16 has less than Two decades records . Or as pointed out 2/3rds of a typical PDO cycle .!!
They extrapolate that El Nino a lowering effect , but that is the Eastern side only .
Diversions of currents during Nino events through the ITF , will most probably give you these anomalies on the Nth West
coast . Ontop of this the entire Project fails to recognise the IOD ...... Typically Piss Poor . !

In their own words they give example of their inaccuracies , and lack of Total understanding to the Forcings .
But that doesn't stop them writing an entire section Noting AGW as causes to a short period anomaly that they are yet to fully understand .

REF. http://www.bom.gov.au/ntc/IDO60202/IDO60202.2010.pdf

Quote " Although simulations of recent sea level rise (eg 1993 to 2003) are in reasonable agreement with observations, longer-term sea level rise has not been satisfactorily modelled. This implies a deficiency in the current understanding, which is partly related to the poor global coverage of high quality historical tide gauge records and the uncertainty in the corrections for land motions. The high-accuracy sea level stations installed for the ABSLMP will help address these issues in the future. "


And Give further thought to this sentence

Quote " Changes in mean sea level as measured by coastal tide gauges are called “relative sea level changes”, because they can come about either by movement of the land on which the tide gauge is situated or by changes in the height of the adjacent sea surface (both considered with respect to the centre of the Earth as a fixed reference) " .
_________________________
SO EN SO .....

Not much to argue about since the IPCC predictions are flat for the next 20 years. there is no way to see any difference between a continuing recovery from the little ice age or an agw signal

The historic sea level rise is about 1.8mm a year (link)

The trend over the last 30 years is about 3mm a year.

Why would the recovery from the little ice age suddenly speed up in the last couple of decades of the 20th century?

Satellite and tidal gauge data are all showing that sea level rise in the last half dozen years has decelerated from about 3 mms / year and now global sea levels are only rising at about an average of 1.7 mms / year.

I would wait for next update . According to Pay TV NG channel the tectonic plate moves by 18mm a year . Before the tsunami it moved by 8 meters .
I assume upwards , thats a lot of water displaced ! 8:30PM sunday a must to watch

SLR is steady @ 3.1mm per year.

Was 3.1 mms but not now. Only about 1.7mms now from recent satellite and gauge records as I posted above and the deceleration in SLR over the last few years can be seen in that graph..

You would expect a bit of up and down due to multi-decadal cycles. which is why there is a slight S shape in the above graph.
Either way there isn't anything close to statistically significant going to come out of this data for a fair while yet.

This graph is extremely dubious. A 2001 IPCC report prediction that starts at 1990. There was no satellite predictions then so the prediction was based on the highly variable station data that even had negative trends at various times. 2mm/year +/-2mm would be an accurate estimation from that data. The satellite data shows much lower variability and so any base line estimation should be made from that.
A pretty nasty case of splicing metrics if i might say so.

The overall trend is where it's at, and that is 3.1mm as shown in the graph.

Obviously it will fluctuate up and down as is shown on the graph. But it is the TREND that counts. The trend, my friend, the trend.

I agree with the trend, thats why the estimate for sea level rise in the 21st century should be 31cm

Another very relevant comment on Sea Level Rise from the "Climate Science" web site of that promoter of "dodgy tricked up articles",[ per spatch] Dr Roger Pielke Sr.

Guest Weblog Post Commentary On ‘Sea Level Rise’ By Madhav Khandekar

above Khandekar Sea Level Rise post continued

Funny how the acceleration in sea level rise coincided with a period during which Co2 has caused an acceleration in the warming rate. Obviously not statistically significant and so nothing to worry about....

Key word/:- Coincided = Coincidence .

As has been concluded exponentially within the last 10-20 years , the Ocean has far more interaction and influence on the Atmosphere than was previously beleived ( unproven ) , and the other way around . Oceanic knowledge is still fledgeling , and accurate measurements on land seem a contentious enough issue in the Atmosphere let alone the can of worms that is about to be uncovered in the
Oceans and its thermal / Co2 Analysis .
To the point that Co2 absorption , storage and release from the Ocean's will be even more hotly debated .

I look forward to empirical data in this regard .

I know this thread is about recent and projected sea level rise, but some might be interested in sea level in paleohistory. I put together all the estimates at one time.

Sea level depends on:

- the degree of continental ice sheets:
- the degree to which continents are gathered together (when the continents are squeezed together, there is less continental shelf and more mountain building and the average depth of the ocean is lower so sea level is lower);
- the maturity of the ocean basins (younger ocean basins take time to sink in the mantle so the average depth of the ocean can be less when new ocean basins are opening).

Just a curiousity I guess but we have had higher sea level when it was colder and lower sea level when it was hotter. All these geologic processes are still working today.

There could also be another reason for the CO2 increase coinciding with the acceleration of the sea level rise which got under way going back to about 1983 before which in the 1970's there was a sharp decline in sea levels again probably due to the cold negative PDO cycle of the 1950's to 1978 and the loss of ocean heat content and a subsequent contraction of ocean waters with sea level falls during the cold period of the negative PDO which was unmeasureable in those days.

Part of the present sea level rise is due to the increase in the ocean heat content which as Khandekar in his Sea Level Rise paper above gives the IPCC projection of 23 cms rise over the next 100 years due to ocean thermal expansion as ocean heat content builds.
[ Love this complete confidence in forecasting 100 years ahead. Could the old guys in 1910 forecast anything that might exist today let alone how hot or cold it would be? ]
So according to the IPCC we are supposedly looking at [ point ] .23mms / year sea level rise due to thermal expansion as the ocean heats up over the next 100 years.

Now as anybody who reads these forums and others will know, when sea water heats up it releases CO2. Conversely when sea water cools it absorbs CO2.
So we have a situation where the oceans were slowly heating up due to a positive PDO, more and stronger El Ninos therefore less equatorial cloud cover and therefore more long wave solar radiation being absorbed by the equatorial oceans and oceans in general so the Pacific ocean and global oceans in general have heated up, gained heat content since about 1983.
In heating up the oceans would have released vast amounts of CO2, the increase of which which has been measured by various stations such as Cape Grim in Tasmania and Mauna Loa in the Hawaiian islands for all those 30 years of the positive PDO until about 2000.

Now according to the 3000 unit ARGO float system, the ocean heat content buildup has stabilised and is starting to very slowly decline over the last 4 or 5 years and this is coincidental or is it, with the onset of a negative phase of the PDO which really got under way in about 2006 after messing around neutral since the end of the super El Nino in 1999.

And Sea Level Rise has slowed right down as Khandekar and others are reporting and would you believe, the steady increase in measured atmospheric CO2 at Mauna Loa observatory is also showing indications of a slowing down in it 's consistent past rise and even showing signs of flattening out over the last year or so.

So what came first, the anthropogenic CO2 increase of about a 100 ppmv over and above the natural 290 plus ppmv CO2 which 100 ppmv due to it's extra warming effects increased ocean heat content and increased SLR and discharged even more CO2 into the atmosphere, the bootstrap effect which nobody has seen. Or did a very old regular approximately 60 year long cyclic phase of the Pacific ocean plus all it's teleconnections to other oceans and the atmosphere switch over into a warming phase around 1980 and then started to release an increasing amount of CO2 as the ocean warmed.
And now the PDO has switched back to a negative cooling phase, the ocean heat content is starting to fall and the oceans cooling ever so slightly and the release of CO2 from the oceans is slowing as per Mauna Loa's data and the global temperature rise has slowed right down and may even be starting to cool due to the reduced input of solar energy from this weak solar cycle which the increased CO2 supposedly traps and thus warms the joint up.

So what came first, the anthropogenic CO2 to cause this recent global warming or the oceans in a long term natural cycle combined with a couple of very intense solar cycles 22 and 23.
And my bet is that it wasn't caused by the anthropogenic CO2 increase but rather the solar effect combined with a natural cyclic ocean phenomena that has existed since the formation of Panama isthmus closed off the Atlantic ocean from the Pacific ocean.

[ AGW relies on the water vapour increase from very small man made CO2 warming effects creating increased evaporation for much higher levels of atmospheric water vapour as the feed back agent that will kick this global warming thing off it we actually ever get to see some definitive proven empirical evidence that it is actually happening and is due solely to increased CO2, not to some or many combined natural cycles and solar influences.
They seem to have forgotten that it rains ,ie; all that water vapour falls out of the sky all over again when you get a lot of it up there. So it just ain't there to collect all that extra heat energy for CAGW from solar sources when needed by the warmistas. ]