Why do some people claim the oceans are lower now than they were 150 years ago?

Question

I've seen this claim made as an attempt to refute global warming. There are good reasons to question global warming and this isn't one of them. The thinking behind it appears to be that is sea levels fall in Tasmania then they fall across the globe. Why would people think that? It's like saying "it's raining here today therefore it's raining everywhere".

The levels of the seas and oceans are not uniform, hence the locks in the Panama Canal even though it links two oceans together.

Can anybody find any evidence anywhere, anything at all, that even hints at the fact that sea levels are falling?

TO MR JELLO.

Thanks for your answer (note I haven't blocked you). It's not slight of hand, you stated that sea levels are falling. Any reasonable person would imply that you were refering to global sea levels and not solely to Tasmania.

You are talking about oceans being lower now than 150 years ago and so am I - no change of subject there.

If you go back through my answers you'll see that if someone asks 'is all this flooding because of GW?' or 'it's really hot here, is that because of GW?' my answer to these and similar questions is 'no'. The reason being that one flood, one hot place, a hot year, a mark on a harbour wall is meaningless by itself.

GW and CC are about long term trends on a global scale. What happens in one place, one country, one year is of little consequence as it proves nothing. Only when long term trends are formed can anything be implied.

I try to be objective, that's why every answer I provide is based on documented facts.

There are other places where sea levels are falling, if I told you where I suspect you would distort the information and use it out of context.

The bottom line is that on a global scale sea levels are rising - that's something no-one can dispute. There are contributory factors other than GW but again, if I mentioned them I believe you'd use the reasons out of context and state or imply that rising sea levels were caused solely by these factors.


TO TARAN WANDERER: An excellent answer, very level-headed. We can't make an informed judgement if we're only presented with partial information - very true.


TO BOB AND DANA: Same thing, informed decisions come from looking at the larger picture and not one sided, selective media articles.

TOMCAT - Good points. The rise in sea levels caused by the last glacial retreat happened during the period 10,500 to 18,000 years ago, since then global average sea level rises were 1mm a year, they're now 3mm a year.

Events such as El Nino, La Nina, cyclonic and anti-cyclonic conditions etc cause uplifting and depressing of the ocean surfaces - they don't add to the volume of water but simply move it around.

STYGAINWOLFE - Thanks for your answer. Evaluating average sea levels is complicated, it requires a series of measurements to be taken and for all variables other than the sea level to be standardised. Satellite telemetry has made th task much easier in recent years.

PERMACULTURE B - You're right, just one person (I didn't want to single anyone out).

To be fair to the skeptics, the reason for underwater villas etc is more down to coastal erosion. Since Roman times sea levels have risen by about 2 metres.

ALFRATTA - Water levels do go up and down but there is an inequality between the two. If average sea levels remained constant it would indicate that either a) nothing was happeing or b) opposing factors were in a state of equilibrium.

Sea levels change through thermal contraction and expansion, salinity, density and volume. Localised changes in these facotrs cause localised variations in the sea level - this is what's happened in some waters around Tasmania (the location referenced by Mr Jello). We would expect a drop in avaerage sea levels and that's just what has been observed - quite normal and predictable.

Yet again you have taken things out of context - a drop in sea levels in one place is proof of nothing, similarly a rise or fall in temps in one place would prove nothing. The changes are not locally restricted, they're happening right across the planet. The global average sea level is rising and so too are the temps.

Here's another challenge (I note you still have a 0% success rate in responding to my challenges) - find any credible document written at any time by any one that so much as hints at a fall in global sea levels. If it's a reality then there should be thousands of such documents.

Once again you've completely distorted what I said about the Panama Canal, taken it out of context and reinvented what I said. This had nothing at all to do with the mark on the harbour wall and was included to demonstrate that there is a natural variation in sea and ocean levels.

Everything I've said can be validated using accepted and documented scientific facts. Everything you've said has been invalidated and shown to be inaccurate - and you accuse me of muddying the waters.

Answer 1

i do not support the belief in global warming, but i think you make a rather significant point that most people never ever think about.......i strongly agree with what you are saying, you can't make a claim about the entire world if you have only ever studied one area........i do not think you can make a claim saying that sea levels are falling if you've only recorded level at one place, that is why i hate this stupid war between people who agree that global warming is a threat and those who say it is not....what ever side you are on you cannot make a claim without giving all of the facts, and in this case, hardly any of the actual facts are there. most people who would read an article that argued this point wouldn't even realise that this scientist only studied one area and is making an assumption on the world as a whole...unfortunately, this accusation can be made to both side of this never ending argument and i believe both would be found guilty......

Answer 2

Trevor,

Sea level has risen over 400 feet since the last glacial retreat, there is not doubt about that. But doesn't the La-Nina/El-Nino event cause several feet of sea level difference in the central Pacific? I think that sends a lot of mixed signals to people.

Answer 3

some people
only one people mentions
150 years
that comes from being schizophrenic

And it contradicts for example, the remains of Roman villas that are lying one kilometer out on the bottom of the sea on the coast of a village in the Algarve called Quarteira .

The 17th hole of the Donna Philipa golf course has fallen into the sea as have several villas build to close to the edge of the red clay cliffs ,

And the locals are saying that the sea is eating their village ,judging from the roman villas for some time already.

Apart from all that ,

The different oceans is mans invention ,all the worlds land mass floats in one world ocean ,not hard to see that if anybody thought to look at an atlas.
There are no canals around Antarctica or the point of South America,
And when the north pole has gone that will also be free flow around
Maybe centrifugal force ,moons pull ,the blockage of large bodies of land ,and gravity account for the differences in levels

look at rocks in a river flow
the water is higher in front of the rocks ,even though the river flows past

Answer 4

Sea levels have always risen and fallen,and changed.To get accurate level is almost impossible since the sea like the planet is an ever changing thing,from the Cretaceous,to the Tissuary and to the present,seas have dropped, risen,moved,changed in salinity,and buoyancy,but since they cannot base global warming theories in atmospheric water vapor worldwide, so they go for the next best thing,puddles we call oceans

Answer 5

I encourage people to look at Mr Jello's link.

http://homepage.eircom.net/~gulufuture/future/weather02.htm

Clearly you'd agree it's biased. And the result is based on one mark on a wall. Here's what some other people say, based on more serious data:

"Historical records show that sea level in San Francisco Bay has risen 18-20 cm (7 inches) over the past 150 years. "

San Francisco Bay Conservation and Development Commission

http://www.bcdc.ca.gov/index.php?cat=56

"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."

GEOPHYSICAL RESEARCH LETTERS, VOL. 33, L01602, doi:10.1029/2005GL024826, 2006

http://www.csiro.au/news/ps13f.html

http://environment.newscientist.com/data/images/ns/cms/dn11083/dn11083-2_426.jpg

(Graph)

This is the best data I've found, satellite data:

http://sealevel.colorado.edu/

Honestly, which of these sources do you find more credible? One mark on a wall, or scientifically measured data with many data points? Note that the various sources I've listed have pretty similar results, too.

Answer 6

Great slight of hand Trevor. I mention the sea levels are lower at one spot today and you quickly change the subject to different oceans. Of course the Pacific Ocean is higher, everyone knows this.

However we are only showing the level at one point at two different times.

I wonder what your reaction would be in the same mark was an inch below the current oceans level. Surly that would be proof that the oceans were rising!

I do admire your effort. I'll bet no one ever accused you of being objective!

Answer 7

water levels go up and down around the globe and that's not proof.
(even though they are "supposed" to be going up)

yet air temps go up and down, but that is proof?

further, your "lock analogy" is bogus.

the mark in question is CLEARY not seperating 2 great oceans via canal.

once again, another feeble attempt to muddy the waters.

Answer 8

Why? B/c they say data is biased or it's a natural change-nothing to worry about.
Same as any denier claim for anything proving GW. Either it's biased info or a mere natural occurrence that we don't need to worry or think about.

Answer 9

Ah yes we've got a new Jello gem.

Apparently it's all based on one sea level measurement. Very rigorous!

http://homepage.eircom.net/~gulufuture/future/weather02.htm