Climate Change and Cascade Flooding of North Sea Coasts?

[cronus]

With the ice caps melting I'm trying to figure out this model in my minds eye of what will happen with shallow areas like the North Sea that are prone to sporadic non-trivial catastrophic flooding. A small change in sea levels with deep water should surely eventually translate into a much larger rise in sea levels with regards shallow regions like the North Sea. Perhaps the weight of water in deep areas will deform the deep surface and delay the eventual flooding but this might also be a mechanism, like a spring, that will lead to a catastrophe - perhaps driven initially by the January high tides or something, but having a momentum of its own to flood large parts of the low land food growing areas of both Europe and England? This model is transferable to other areas but The North Sea is likely to be the first place to suffer the consequences of runaway climate change like this?

[Thinking Aloud]

A small change in sea levels with deep water should surely eventually translate into a much larger rise in sea levels with regards shallow regions like the North Sea.

Not really, what with water's ability to flow from one place to another. Average sea level will rise globally, but approximately evenly.

[cronus]

A small change in sea levels with deep water should surely eventually translate into a much larger rise in sea levels with regards shallow regions like the North Sea.

Not really, what with water's ability to flow from one place to another. Average sea level will rise globally, but approximately evenly.

I'm not so sure. Seems the deeper water will be far heavier and cover larger areas that it will take more meltwater than lower areas...deforming the deep seafloor to take the water. This will happen until the tides, the moon....changes the dynamic, and if it doesn't for several years quite a lot of water could 'build' in the deep water...?

[JimC]

A small change in sea levels with deep water should surely eventually translate into a much larger rise in sea levels with regards shallow regions like the North Sea.

Not really, what with water's ability to flow from one place to another. Average sea level will rise globally, but approximately evenly.

I'm not so sure. Seems the deeper water will be far heavier and cover larger areas that it will take more meltwater than lower areas...deforming the deep seafloor to take the water. This will happen until the tides, the moon....changes the dynamic, and if it doesn't for several years quite a lot of water could 'build' in the deep water...?

No.

[cronus]

I've been wrong before I must admit.

[Rum]

I've been wrong before I must admit.

[cronus]

I've been wrong before I must admit.

I've been right too.

[Rum]

I've been wrong before I must admit.

I've been right too.

[Thinking Aloud]

A small change in sea levels with deep water should surely eventually translate into a much larger rise in sea levels with regards shallow regions like the North Sea.

Not really, what with water's ability to flow from one place to another. Average sea level will rise globally, but approximately evenly.

I'm not so sure. Seems the deeper water will be far heavier and cover larger areas that it will take more meltwater than lower areas...deforming the deep seafloor to take the water. This will happen until the tides, the moon....changes the dynamic, and if it doesn't for several years quite a lot of water could 'build' in the deep water...?

In terms of isostatic rebound rates, Scandinavia is still rising following the loss of ice at the end of the last ice age. I'm having trouble picturing what you're trying to describe, though, since if you have two basins, one deep and one shallow, interconnected at the surface, no matter how much water you add, the levels in both will still be equal - higher, yes, but still the same. The only reason for a particular body of water to be higher is if the interconnecting waterways are very narrow, leading to a lag as water drains from one to the other - the North Sea is open at its top end to the Atlantic.

[cronus]

The deeper water covers a far larger area. The continental shelf not only has less water at any given time but is also a basaltic plate which is not elastic. There are parts of the South Atlantic where the mantle is showing through the crust....that is the weight of water, the power of the sea when it's deep. So a sudden increase in meltwater seeps into the deep water which like a plastic basin absorbs to a point...water which would cause a much larger rise if there was no elasticity....etc...moon, storm surge and elastic rebound of a rapid increase in water volume...sudden large scale flooding of lowland areas, not temporary.

[Thinking Aloud]

The continental shelf not only has less water at any given time but is also a basaltic plate which is not elastic.

Um ... what?

Ocean floor is basaltic - continental crust (including the continental shelves) is not.

There are parts of the South Atlantic where the mantle is showing through the crust....that is the weight of water, the power of the sea when it's deep.

Um... Just no. No, there aren't.

So a sudden increase in meltwater seeps into the deep water which like a plastic basin absorbs to a point...water which would cause a much larger rise if there was no elasticity....etc...moon, storm surge and elastic rebound of a rapid increase in water volume...sudden large scale flooding of lowland areas, not temporary.

Any sudden increase in water volume will not cause a significant "plastic" deformation of deep ocean basins on the timescales you're suggesting. For the purpose of your hypothesis (a sudden addition of meltwater), you can treat the basin as being made of concrete. It won't "absorb" anything in the short term, thus the meltwater will not collect anywhere preferentially - it will simply spread out evenly into available space. Over the very long term (tens of thousands to hundreds of thousands of years) you'll see some elastic effects as the lithosphere adjusts.

[JimC]

TA is perfectly correct. As already mentioned, the only way the sea level will not "even out" is a very temporary situation involving land-locked bays and tidal movements.

[cronus]

I could still be right in the round though? The Ocean will absorb a lot of water under elastic deformation. Forget that I'm wrong on minor details. The main thrust of my argument is still intact.

[JimC]

I could still be right in the round though? The Ocean will absorb a lot of water under elastic deformation. Forget that I'm wrong on minor details. The main thrust of my argument is still intact.

Elastic deformation of the crust under ice sheets in previous glacial eras is a recognised phenomena, but the pressure they exerted was not evenly spread. The increase in pressure exerted by a given rise in sea level is spread evenly across the entire sea bed...

[cronus]

I could still be right in the round though? The Ocean will absorb a lot of water under elastic deformation. Forget that I'm wrong on minor details. The main thrust of my argument is still intact.

Elastic deformation of the crust under ice sheets in previous glacial eras is a recognised phenomena, but the pressure they exerted was not evenly spread. The increase in pressure exerted by a given rise in sea level is spread evenly across the entire sea bed...

The crust is thinner in the Atlantic than other places. Another variable to consider.