# Calculated sea surface rise from total Greenland melt

by zankaon
Tags: calculated, greenland, melt, rise, surface
 P: 166 What might be the calculated sea surface rise from a total Greenland melt? http://en.wikipedia.org/wiki/Sea_level_rise Volume of ice in km^3 /surface area ocean km^2 = rise in km. S.A. of earth is 510 x 10^6 km^2. ocean is 71% of S.A., or 361 x 10^6 km^2. http://en.wikipedia.org/wiki/Earth Greenland area is 2.166 x 10^6 km^2. 81 % is ice/water or 1.75 x 10^6 km^2. http://en.wikipedia.org/wiki/GreenlandThe key missing ingredient is average ice depth. perhaps 2-3 km at deepest, with central basin of about 1000 ft below sea level. If 1 km av depth, one gets 4.1 meter sea level rise. For .5 km av depth, one gets 2 meter sea level rise. One contained reference mentions 7 meters. http://en.wikipedia.org/wiki/Greenland But wouldn't one also have to consider caveat of part of melt occupying Greenland basin, leaving an archipelago?
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 P: 748 Only the grounded ice that melts will cause sea level change. Floating ice displaces its own weight in water anyway, so if it melts sea level won't change -- basic physics.
 P: 252 Actually the floating ice that melts will lower (albeit it miniscule) the sea level. Remember frozen water expands by 9%.
 PF Gold P: 5,459 Calculated sea surface rise from total Greenland melt it's about grounded ice but without isostacy assumptions, since the loss of ice will cause uplift in Greenland compensated with subsidence in the oceans, which tends to reduce the sea level rise eventually. But the Greenland ice survived much warmer periods then now, the Hoocene Thermal Optimum for instance from about 9000-6000 years ago, 3000 years of 2-4 degrees higher temperatures. The ice sheet can handle that.
 P: 748 No binzing, the water level would not change if floating ice were to melt, at least i t won't if Archimedes was right. One other minor complication though, the gravitational pull of an ice sheet actually causes the sea to bulge slightly around it, without the ice sheet this bulge wouldn't be present causing local sea level to be slightly lower than it otherwise would have been within the vicinity of the ice sheet. The glacial rebound would also make sea level lower (relative to a fixed marker) in the vicinity - but due to mass balance the sea level would be higher elsewhere around the world to compensate.
Emeritus
PF Gold
P: 11,155
 Quote by Andre it's about grounded ice but without isostacy assumptions, since the loss of ice will cause uplift in Greenland compensated with subsidence in the oceans, which tends to reduce the sea level rise eventually.
Andre, can you explain this in layman terms? I'm not sure I follow. Also, what would be the typical timescale for uplift and subsidence?
 PF Gold P: 5,459 This effect is what is called isostacy. Perhaps, this explanation will be helpful, which also covers the rate of changes. But not shown in the animation is that the increased sea level exerts slightly more pressure on the ocean floors and that the total uplifted mass below the former ice sheet should be balanced out by an equal mass subsiding elsewhere. Assuming balancing pressures in the upper mantle or asthenosphere to be about equal everywhere, for this balancing, the now heavier oceans are a logical candidate, this is called Hydro-isostacy.
 P: 748 Caltech seem to be doing some interesting theoretical geophysical assessments of glacial rebound. http://www.gps.caltech.edu/~jtromp/r...h/glacial.html A spherical harmonic analysis of the geogravitational field could theoretically be used to monitor the behaviour of ice sheets and tectonic plates.