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In reading the question What would the geology and climate of a supposed landmass near the pole be like, assuming a thoroughly warmer planet?, it came to mind that another factor may cause a shift in the long term climatic patterns should the Greenland Ice sheet continue melt - the effects of a 'taller' Greenland, due to its isostatic rebound.

According to the Polar Field Services website,

The enormous weight of the ice down-warped the land surface, causing the material underlying these land masses to slowly flow away. The physics are similar to the reasons a balloon deforms when you press down on it. In the same way that the balloon reshapes itself when you remove your hand, the land actually pops back up over several thousand years when the weight of expansive ice sheets no longer weighs down the underlying area. In Greenland, where the ice sheet is currently receding, the island is actively rebounding.

Given that there are already peaks of up to about 3.7km in altitude, my related questions are:

  • How high would these peaks go?
  • What effect would a 'taller' Greenland have on climatic patterns?
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Be warned this is a general (and speculative) answer, but it was getting too long to be a comment: The bulk of Greenland's ice mass is centred over inland/central Greenland. If you were to take all the ice away today, much of central Greenland would actually be below sea level, by several hundred metres in fact:

Greenland without ice

Glacial isostatic rebound would seek to equilibrate the loss in mass by 'popping' Greenland back up, but it appears that we'd be starting from at or below sea level over much of the island! I'm afraid I don't have any figures to hand over what the total isostatic adjustment might be in the centre, but I would be skeptical of it producing peaks any higher than the current ice sheet level - so the net effect on atmospheric circulation in this region may be small.

Interestingly, the post-glacial isostatic adjustment going on in that region is not as simple as may be expected, some areas over Greenland are actually still sinking, due in part to the movement of former ice mass from the Arctic into the seas around Greenland (as water). The figure below indicates that the areas to watch are actually Canada and Scandinavia, at least for now. Isostatic adjustments globally

For the existing tall peaks that are rebounding, in general terms you could potentially expect more orographic precipitation enhancement as they became higher, more erosion, which could lead to greater drawdown of CO2 from weathering...the arm-waving speculation goes on... (but see this question.)

From a regional climate aspect, I would perhaps be more concerned over the decrease in albedo on Greenland from the loss of its ice cap. Also, the potential effect of changing surface moisture fluxes to the atmosphere, should central Greenland end up becoming a series of lakes and islands (rather like Finland in its post-glacial state today).

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    $\begingroup$ Good answer. I would expect the height of the rebound to be much less than the current ice height since the density of rock is about 2.5 times greater. $\endgroup$ – haresfur Jan 14 '15 at 22:11

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