Rising sea levels.

[109er]

And before you say it should be in 'climate change' read on.

I have always argued that a lot of/most of the so called rise in sea levels is
man made - literally 'man made'. Only today in the news they have launched
the worlds largest ship that displaces 134,400,000 cubic feet of water.
Now add this to god knows how many more cubic feet of water the rest of all
shipping afloat today, and the only place that sea/water levels can go is UP!

My question would be, 'If every single item that floats' was removed from the
water world wide, by how much would the sea/water level drop?

Remember, the must in total be a few billion tons floating world wide.

PS. Or Archimedes was wrong.

[kambites]

The Oceans cover 360,000,000,000,000 square meters. So the Ocean level will rise by 1mm per 360,000,000,000 tonnes we float. In 2008, the total merchant shipping tonnage was just over 1bn; so would have raised sea level by 3 micrometers. Even if it's ten times that today, it'd still only be 30um (0.03mm).

Edited by kambites on Thursday 5th December 09:16

[Krikkit]

I'm sure we've had this question before - I did a back of the envelope calculation on how many ships are out there by volume compared to the volume of the seas and oceans, it was something like 0.0001%.

[Finlandia]

I thought the rising sea levels in UK and NL (and a few other places), or more like sinking landmasses, was due to the rising land masses in Western Finland and Eastern Sweden (and a few other places), the so called post glacial rebound is 8.5mm per year in the Gulf of Bothnia.

[Squirrelofwoe]

XKCD 'What-if' covered this a while back, they reached the conclusion that if you removed all the world's shipping the sea levels would fall about 6 microns (0.006mm) whilst sea levels are rising approx 3.3mm per year...

http://what-if.xkcd.com/33/

[plunker]

In the other direction, you've also got increased water storage on land in man-made resevoirs etc.

Interesting fact - if the polar icecaps melted, sea level at high latitudes would fall.

[Eric Mc]

Are sea levels actually rising?

[Lotus 50]

Yes, the amount of rise is variable globally but, if I remember correctly it is going up by 1-2mm per year.

[Eric Mc]

Where is it being measured and how much is taken into account of the rising and falling of land. Are they actually saying that the amount of liquid water on earth is rising and do they have proof of this - or is it all theory and modelling.

[MOTORVATOR]

Lotus 50 said:

Yes, the amount of rise is variable globally but, if I remember correctly it is going up by 1-2mm per year.

For what reason though? Where is all this additional water coming from?

How much is attributable to each of the reasons - thermal expansion, sea bed rise, land drop, alien water arriving on the planet, ice melt, ship building etc etc.

I seem to remember some sort of research a few years back that showed parts of Scotland won't see any sea level rise due to climate change whilst parts of England would see double what could be expected due to the tilt.

If we had those figures we could then decide whether we could do something about it or err just move to higher ground.

[andy_s]

kambites said:

The Oceans cover 360,000,000,000,000 square meters. So the Ocean level will rise by 1mm per 360,000,000,000 tonnes we float. In 2008, the total merchant shipping tonnage was just over 1bn; so would have raised sea level by 3 micrometers. Even if it's ten times that today, it'd still only be 30um (0.03mm).

Edited by kambites on Thursday 5th December 09:16

Basically like trying to flatten and spread all boats over the ocean surface area, imagine how flat they would have to be.

[Simpo Two]

I measure the water level from my boat. It only goes up when lots of people get on board. Therefore I deduce the world has too many people on it.

[MOTORVATOR]

Simpo Two said:

I measure the water level from my boat. It only goes up when lots of people get on board. Therefore I deduce the world has too many people on it.

This is logical. I have also noticed that the boat floats quite low in the water before a session and high when we return to the pontoon. I have therefore decided to add a plimsoll line to readily determine the quantity of Gin left on board.

[Simpo Two]

But gin is lighter than water. I presume the weight of your new range of plimsolls makes up for it?

[MOTORVATOR]

I think I'm getting the hang of this. So what you are saying in a roundabout way is that there aren't too many people, just that they haven't drunk enough Gin?

[Lotus 50]

Eric Mc said:

Where is it being measured and how much is taken into account of the rising and falling of land. Are they actually saying that the amount of liquid water on earth is rising and do they have proof of this - or is it all theory and modelling.

There is a global network of monitoring stations that measure sea levels and the tides (both onshore and offshore) these are also linked to satellite measurements of the land/sea surface. It's also possible to estimate historic sea levels from sediment deposits etc. The net figures for sea level rise will usually take account of changes in land elevation (e.g. the north of the UK is rising by approx .8mm pa the SE is sinking by a similar amount). If I recall correctly over the last century global mean sea levels increased by 10-20 cm, in the last 20 years the increase has been something like 3mm pa (more than I thought!). The rise is linked to thermal expansion of the oceans and ice melt and yes the changes have been measured, not modelled.

So we need to do a lot more gin drinking (and quickly if we want to have ice with it)!

Edited by Lotus 50 on Saturday 7th December 13:01

[Eric Mc]

How does a satellite "measure" the ocean?

What is it looking at?

If the sea levels truly are rising, is the surface area of the earth being covered by more and more liquid water each year?

Is this the best way to "measure" water levels?

How can they tell whether "£rates of change" are faster/slower than periods in the past?

[B17NNS]

Of course it's going to keep rising. It rains on it right?

[MOTORVATOR]

Lotus 50 said:

So we need to do a lot more gin drinking (and quickly if we want to have ice with it)!

Edited by Lotus 50 on Saturday 7th December 13:01

I'm on it as soon as I've had a bath, don't want anyone accusing me of being one of those environmentalismists ok?

If we all have a bath and leave the plug in would that help?

[TheExcession]

Lotus 50 said:

Yes, the amount of rise is variable globally but, if I remember correctly it is going up by 1-2mm per year.

This is no dig at you Lotus but seriously how does one measure a 1-2 mm rise in sea level?

I'm looking at a metric rule on my desk and reckon that a endangered species pregnant bat furiously flapping its wings could disrupt water enough to record a 1-2 mm rise in a water level measurement. Just imagine what a fat swan or ducks fed on lard could do. It just doesn't bear thinking about..... Terrifying!