As the polar ice sheets are floating ice-bergs, why if they melt will sea levels rise ?

Question

As floating bodies displace their mass, and as the ice cap of the north pole is all floating, and the periphery of the Antartic is all floating ice sheets too, Why if these polar ice caps melt, are sea levels forecast to rise ?
Surely any effect on sea levels because of melting polar ice caps will be negligible ?

Answer 1

Two reasons:

1. warmer water thermally expands

2. Sure, floating ice melting does not contribute to seal level rise, but a lot of ice is on land, not floating as you claim.

Answer 2

Hi. The problem is not with floating ice. It has to do with two other phenomenon. 1) The ice on land can slip into the water and cause an immediate rise in sea level without having to melt. 2) As the ocean water warms it expands. This is predicted to raise the sea level by 6 feet. Think of a column of water as deep as the ocean having it's temperature raised by 1 deg C.

Answer 3

You've sort of already answered your own question. The polar ice sheets are FLOATING. They are above sea level. It's a bit like when you float a ball in the bath, the water level doesn't rise, but if you push the ball under, the balls volume forces the water level to rise.

So when the polar ice sheets melt, their volume will become part fo the sea and therefore increase it, like that of the ball in the bath example.

Answer 4

Ice sheets are like mountains built up not out. Snow piles up on a mountain. But the melted water runs down into a valley.
They are like stacked up. If just half were to melt the current land surface would be under 100' of water. Most coastal regions and low lying areas would be under water. If all melts like a astroid to close to the earth or global warming all over and it all melts.
the low dry land of earth would be under 200' of water.
Some mountain ranges would be like Hawaii and rise above.
Hawaii is actually the tops of mountains. In a sea of water all that would remain is the tops of very high mountains.
I think it said 14,000 ' elevation. Northern New mexico and some other states colorado and California would become The island of California.

Answer 5

True, but the ice covering the land is also forecast to melt. That could lead to a rise in sea level. Also, as water warms it expands and takes up more room.

Answer 6

They won't. The melting of floating ice has an effect which is not just negligible -- it is zero. The rise of sea level, if it occurs, will come from the melting of ice now on land -- Greenland and Antarctica.
Postscript, for Cirric (response subsequent to this): Thermal expansion will not cause the sea level to rise significantly because the vast bulk of the water will remain at 4 degrees C, irrespective of what happens at the surface. Hence, the thermal expansion can be ignored.

Answer 7

A few of you have stated that the ice will thermally expand, but don't forget, this is just counteracting agasint the actual decrease in mass when ice turns to water (i.e. ice contracts when it turns to water).

However, as many of you have mentioned, the large amount of ice that sits above the water (be it on land or above the sea) is not displacing the sea water in the slightest.

Answer 8

Ask the question a different way round. The Land masses are sinking slowly. The coastlines are eroding at a very fast rate and falling into the sea. If you think of a jar of water then add water to it the water runneth over!

Answer 9

Any ice ABOVE sea level currently has no influence on sea level until it melts into the sea

Answer 10

Of course sea levels will rise, where else is the water going to go?
Scientists predict that a rise of only a couple of inches, will cause the loss of a high percentage of the land worldwide.