This seems to be his basis of thinking:
I'm thinking this falls under "not even wrong" at most, or "just plain wrong".
Indeed, I'm confused as to this thinking.

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This is no fantasy. No careless product of wild imagination. - Jor-El

Godspeed, John Glenn. - Scott Carpenter

And these atomic bombs that science burst upon the world that night were strange even to the men that used them.
- H.G Wells, The World Set Free

To the conspiracy crowd, radiation is a big Boogey Man that inspires terror and death in all who encounter it. - JayUtah

I've been trying to find a reference stating that Scandinavia and Hudson Bay are rebounding, but can't find it. I don't doubt it; it's just to show my denier friend (he tried a search too and came up with nothing).

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This is no fantasy. No careless product of wild imagination. - Jor-El

Godspeed, John Glenn. - Scott Carpenter

And these atomic bombs that science burst upon the world that night were strange even to the men that used them.
- H.G Wells, The World Set Free

To the conspiracy crowd, radiation is a big Boogey Man that inspires terror and death in all who encounter it. - JayUtah

Whoa, stretching the limits of credulity there! Most of the upper mantle rebound has occurred, but I'll see what I can come up with.

Science 23 March 2001:Geodynamics Program of the Geological Survey of Canada:

Actually a little more than that, I understand. But isostatic recovery will add more than half an extra metre (eventually). I'm sorry to have confused the point.

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There are a lot of maps showing the total rebound since the end of the last ice age, such as the ones here. Scroll down to the section headed "Regional Vertical Movements of the Crust" for the maps, and notice the remark:Maps showing that the land is still rising are a little harder to come by, but here is one for Scandinavia. showing that the ongoing rate across a broad swathe of the area is measurable in mm/yr. Likewise, here is a description and map of the ongoing rebound in Canada (reference to the original article in Science appears at the bottom).
Finally, some supporting evidence for Scandinavia is here. The first paragraph under "Examples of Vertical Land Movements in Tide Gauge Records" contains a link to a "First example plot" of sea levels at various European stations. Over the last 200-year span, it's clear that Stockholm is bucking the local trend and rising out of the sea, an effect the parent page ascribes to "Glacial Isostatic Adjustment (sometimes called Post Glacial Rebound, PGR) in Scandinavia".

There's a lot more around, I've just picked the first few samples that do the job and appear to have credibility. Searching on "Glacial Isostatic Adjustment" or "Post Glacial Rebound" will find you much more.

Grant Hutchison

From Grant's link
http://www.uwgb.edu/dutchs/STRUCTGE/EarthMvts.HTM
This is exactly the situation that will occur when and if the Antarctic sheet melts; a shallow, central sea will exist between East and West Antarctica which will gradually empty into the ocean and disappear as the continent rebounds, thereby raising the ocean level.

One interesting aspect is the question of how isostatic recovery occurs at all; does it include a flow of material in the upper mantle towards the rebounding region, or is it simply due to a decrease in density in the local rock? I expect it would be a bit of both.

But note that a flow of material in the upper mantle towards Antarctica could, just conceivably, lower the level of the sea-bed and so lower the level of the ocean a little. But I think this effect would disappear after a while as the plastic aesthenosphere found its own level.

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If it's going to be isostatic, it not going to be the second one at all. A decrease in density does nothing for isostatic compensation.

Density and expansion are very interesting factors. I notice when one freezes water in a sealed container there is a fair bit of expansion. It is supposed to happen at 4 degrees Celsius which is 39.2 degrees Fahrenheit.

If there was a significant volume of water cross this expansion point wouldn't the action of enough of it cause the water in the in the oceans to swell?

Isostatic recovery variations could be far less immediate than crossing a thermal expansion point. Then there is the water to salt ratios to consider. It does become quite a complex model.

True; but the decrease in density would contribute to the rise in the land surface, and hence to the rise in sea level.

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I was just addressing your comment: "One interesting aspect is the question of how isostatic recovery occurs at all;"

Still, solid rock materials don't usually expand a whole lot.

Just for clarification, I wasn't trying to say anything about ice caps melting. I was responding to something somebody claimed on that other forum, which is that the water level in a glass of ice water should drop as the ice melts.

it's true of course that the water level does not change.

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So here's a kiddie pool analogy that I think might be a little more closely related to reality: Fill a kiddie pool with water. Simulate the rebound by pushing the underside of the pool so that it sticks up out of the water. Now, I predict that the water level in the pool will be quite a bit higher because that "island" we've created will displace so much water. I also predict that higher we push this "island" up out of the water, the more it will displace.

Possibly G_L's friend should actually be arguing that the rebound will be extremely slow, since it sounds to me like a whole continent lifting higher out of the water should have the opposite effect of what was claimed.


As for causes of the rebound, the link I posted a while back suggests that the sinking is due to deformation of the lithosphere. Evidence for this includes that as Scandanavia rises the Netherlands is sinking, which fits with the theory in that a region of the lithosphere pressing down should displace the asthenosphere, which will put some upward pressure on the lithosphere in the surrounding area.

While I'm sure packing of the strata happens, I would guess that it doesn't contribute much to the isostatic rebound for about the same reason that a canister of flour doesn't fluff itself.

But a flow of upper mantle from beneath the ocean floor of the Great Southern Ocean towards the Antarctic isostatic adjustment would actually lower the seafloor in that region, lowering sealevels somewhat.

I proposed a (semi-serious) solution to rising ocean levels a while ago on this forum; by excavating the continental shelf and building new countries from scratch, we could lower the net sea-floor level and thereby the level of the ocean surface. By causing a net flow in the mantle beneath the Great Southern Ocean towards Antarctica there could be a slight lowering of the Ocean after all.

Eventually, that depression in the seafloor would also adjust istself, as upper mantle flows in from the rest of the world... wouldn't it? Hmm. This is somewhat more complex than I thought at first.

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continent/ country building?


that takes a lot of gasoline.

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"I will do my best to understand and explain the universe from big to small without invoking miracles, unrepeatable events, or divine intervention. In place of those things I will use observations, mathematics, and science."


-Cross
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Some of my Astrophotography


Those that lack education have a hard time understanding its value. - Cross

A cheaper method should be to pump seawater into antartica and either let it run and freeze or pump it into giant dams. This would of course still be massively expensive. Pumping a ton of water a hundred kilometers is expensive. Pumping gigatons is even more expensive. (Could never figure out why in those fat Kim Stanley Robinson novels they could teraform all of mars but earth couldn't handle rising sea levels.)

science fiction.





one other thing, Mars has a pretty stable environment with fewer influences than earth. By adding bacteria or whatever they used - this created a huge influence that wasn't there before. Kind of like adding Kudzu to the eastern US - only more powerful.

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"I will do my best to understand and explain the universe from big to small without invoking miracles, unrepeatable events, or divine intervention. In place of those things I will use observations, mathematics, and science."


-Cross
My travel blog

Some of my Astrophotography


Those that lack education have a hard time understanding its value. - Cross

Thanks for all the replies. Quite a bit to digest.

And kudos, Nauthiz for a visualization that makes more sense (about the kiddie pool and displacement). I think that is what I was missing in my mental image.

About rebounds, I suppose the nature of the magma underneath an area effects wether or not an area does rise after ice melts from it, yes?

__________________
This is no fantasy. No careless product of wild imagination. - Jor-El

Godspeed, John Glenn. - Scott Carpenter

And these atomic bombs that science burst upon the world that night were strange even to the men that used them.
- H.G Wells, The World Set Free

To the conspiracy crowd, radiation is a big Boogey Man that inspires terror and death in all who encounter it. - JayUtah

Part of the problem with the kiddie pool analogy like that is that a displacement of the bottom in one area will be compensated in another. Like what you mention about the Netherlands in the last part of your post.
Just whether or not?

Not on Earth, I don't think. It could be possible that an accumulation of ice on a particular part could result in a rise of that part, because of the interaction of water weight on the rest of the surface, but I don't think the conditions obtain on the Earth if they can at all.

Right, and like ebracum suggested I imagine that there's a good chance that the net effect (ignoring any other factors) would be to lower the sea levels a bit. It's definitely not a good version of the kiddie pool; I think you're right that the analogy is fundamentally unsound.

It's definitely trickier than the kiddie pool. Due to conservation-of-crust, if a cubic mile of crust "rises" somewhere, another cubic mile must "sink" somewhere.

It's not immediately obvious that isostatic rebound would have any effect on global sea-levels

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It'd depend on the details on those two cubic miles.

If the bit that rises consists entirely of dry land, and the bit that sinks is entirely covered by water, then the net effect would be for sea levels to drop by whatever 1 cubic mile divided by the surface area of the ocean is.

If the aquatic status of the two bits of land were switched, then the sea levels would rise by the same amount.

Geology (or is this another subject?) sure is tricky.

I figured that with the situation, that the shifting of the level of Antartica doesn't really alter sea level, because the volume of water is what really matters. All the shifting and rebounding does is alter the shape of the container.

Or am I totally wrong in this?

__________________
This is no fantasy. No careless product of wild imagination. - Jor-El

Godspeed, John Glenn. - Scott Carpenter

And these atomic bombs that science burst upon the world that night were strange even to the men that used them.
- H.G Wells, The World Set Free

To the conspiracy crowd, radiation is a big Boogey Man that inspires terror and death in all who encounter it. - JayUtah

Depends on how the container is shaped, doesn't it? Haven't we all squeezed a styrofoam cup of coffee and got it all over us? Or is it just me?

What about the weight per cubic kilometre of water to average crust. Water would quickly adjust. Due to the slower rebound could that make a change to rebound?

Cheers

Yes the coffee incidents, in direct proportion to how embarrassing the timing is.

No - when I need to get out of a meeting, I prefer to pour the coffee over my head and run out of the room while laughing maniacally. That way nobody will think I'm uncoordinated.

Interesting, I might have to try that. Do you sit long enough to let the coffee cool? That could be a negative.

I had in mind a container in the shape of the ocean floor.

I would suppose if THAT was squeezed, we'd have a mess. And not just jumbo squid.

__________________
This is no fantasy. No careless product of wild imagination. - Jor-El

Godspeed, John Glenn. - Scott Carpenter

And these atomic bombs that science burst upon the world that night were strange even to the men that used them.
- H.G Wells, The World Set Free

To the conspiracy crowd, radiation is a big Boogey Man that inspires terror and death in all who encounter it. - JayUtah

Still, the devil is in the details. For instance, if you have a perfectly round planet with a water layer at the surface, and the center of mass of the solid portion is not at the center of figure, the water will be displaced to one side. A "continent" will emerge on the other side. As the center of mass moves towards the center of figure, the floor of the ocean will rise, and the sea level on the continent will rise.

The shape of the container can make almost anything happen. That's a simplified model, but it has real world analogues.

That makes sense.

Now suppose the water warms. Due to thermal expansion the sea level will rise. But what if the continents also warm?

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