Geologic and earth-dynamics effects due to ice-sheet melting??? 1

[WKTaylor]

As I understand it, there is geologic evidence that as glacial ice melts/thins/retreats it relieves [un-strains] the underlying terrain of the compressed mass of several hundreds/thousands of feet of ice... which results in a terrain lifting phenomena due to load-relief. Apparently this decompression/lifting phenomena has been observed in various places as ice-age glaciers retreated. It also seem evident on a smaller scale n certain civil engineering projects where terrain compression-rebound phenomena is quantifiable.

Likewise NASA studies have quantified the effects of dense/thick ice mass-concentrations distributed around the world which have a quantifiable effect on earth's rotational dynamics... such as period and 'wobble'.

IF a large mass redistribution were to 'suddenly' occur [geologic blink-of the-eye], due to rapid/dramatic ice-mass thinning/loss... along with terrain decompression... I suspect there could be some less-than predictable changes in-store for mother Earth's rotational dynamics... in the not-too-distant future.

Regards, Wil Taylor

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[btrueblood]

Whee!

 

[IRstuff]

Ooh, that's great! The mass of the Greenland ice mass is 1/7500th the mass of the North American plate, which is equivalent to about 20 meters of plate thickness, so the NA plate will float higher, probably resulting in little or no flooding for North America.

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[rb1957]

I'd've thought that Greenland would "rebound" as the ice (pushing it down) melted away.

another day in paradise, or is paradise one day closer ?

 

[miningman]

Wouldn't be surprised if there's an element of truth and credibility in the OP's post . Hope there is no intention/ desire to ask me to modify my lifestyle to prevent / minimise these effects. I'm too busy trying to reduce my carbon footprint , reduce my plastic usage , minimise the local cows methane emissions, and to reduce my usage of non politically correct expressions ........ and after 65 years of using them its highly stressfull which may lead to a heart attack and increasing my demands on the health system

 

[Ron247]

Locally, we have passed an ordinance making it illegal for cows to say "pull my hoof".

 

[SuperSalad]

Wait...but with all that ice melt, the decrease in ocean salinity will also make the land less buoyant. So the decrease in weight and the decrease in buoyancy should cancel one another out and the land masses will continue floating at the same level.....that's how islands work right?

Andrew H.

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[IRstuff]

The land isn't floating on the water; it's floating on magma

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[cswilson]

The phenomenon is called "isostatic rebound", and it's still going on.

Here's a plot from NOAA of the measured sea level at Juneau, Alaska:

It shows the sea level there dropping 13 mm/year. With global sea level rise at about 2 mm/year, the ongoing rebound is about 15 mm/year.

It's similar in places like Scandinavia that were also covered in the last glacial period.

The counterpart to this is that areas just south of where there were glaciers are actually falling as the mantle under them slowly oozes back towards the poles, so sea level rise there is greater than average.

 

The Great Lakes region is still rebounding from the last ice age.

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[JayMaechtlen]

Seems like a non-trivial topic.
If there were no currents in the fluid (magma) part of the earth, you'd expect a uniform mass distribution - localized weight of rock + water would become uniform. Since rock density>water density, you'd expect shallow seas.
But we seem to have circulation within the fluid regions, and very non-uniform distributions of mass. Continental plates drifting around and bumping into each other.
So - we can expect Greenland to begin rebounding as its ice melts - and that will displace a bit more sea water, adding to sea level rise elsewhere.
Ditto Antarctica, though much of its ice is over water, which shouldn't affect rebound.
Tough luck for those islands not rebounding, of course.


Jay Maechtlen

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