Ice caps melting = water rising?

pikapika!

I've heard that if the ice caps melt the oceans will rise.

but i thought that water expands when freezing.

is this a myth?

ukmicky

It does but the ice they are talking about is sitting on land rather than the sea.

Pythagorean

It just won't be proportional to the size of the ice that melts, but it will still contribute to the sea level.

Langbein

It's true that most of the melting ice is on top of land, like the ice cap of Greenland.

But then for the floating ice:

Take a glass of water and put an ice cube into it. Wait until it melts. Which way did the surphase of the water in the glass move, up or down?

Where will the expanded part of the wather when freasing to ice normally be located, for a floating ice cube ?

cristo

Neither.. the water level remains the same.

DaveC426913

The density of floating ice vs. water has no effect on water level. See diagram.

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Langbein

Yes, you are right. I should not speak about experiments without performing them. The volume above the surphase should be exaclty the same as the expansion volume so there should be no change at all - right ?!

Shame, stupid me ..

billiards

In the short term we shouldn't be too worried about ice bergs and ice shelves melting, because they are floating so when they melt they do not contribute to sea level rise. It is grounded ice that melts that will contribute to sea level rise, the largest ice caps on earth are grounded (e.g. Greenland, Anterctica).

Q/What is the single largest contributor to sea level rise?

A/Thermal expansion. Because when you heat water up it becomes less dense (i.e. its volume increases), and because water is a fluid, it will spread its volume evenly over the entire ocean (ignoring self-gravitational effects).

Pythagorean

I think he's referring to ice on land, as from the North and South (an) arctic.

Plastic Photon

True, but would you say this is an appropriate analogy, to compare the earth's oceans to a cup of water?

Evo

Ice melt from ice over water will not increase sea level, only ice melt from ice over land will have an impact and it will not be uniform, there will be variations with rises in some areas, while other areas could see a fall.

Ivan Seeking

The main concerns are the melting ice in Greenland and the Antarctic. Expansion of the water from heating is also a factor.

Evo, I was not aware of any predictions that water levels could fall in some areas. Where does this come from?

Evo

From the IPCC, from the EPA...

http://www.epa.gov/climatechange/eff...tal/index.html

billiards

The most likely cause I can think of for the variability would be uplift and subsidence of the crust. E.g. SE England's coast will become submerged even if global sea levels do not change, the land is subsiding as mantle material diverges towards the north of Britain which is currently undergoing isostatic rebound in response to the melting of the ice cover at the end of the last glacial maximum.

Andre

Meanwhile Hudson Bay and the Baltic sea are on it's way to become land.

Plastic Photon

A rapid melt in arctic ice with an inhibited flow into the Atlantic could submerge islands in the arctic. The situation depends on whether the melting of ice is uniform or a sudden gush. I have to believe that either way, the melting of the artic ice cannot be felt uniformly throughout the world's oceans. If say for some reason, a large iceberg cuts off the Berring, and the arctic ice melts, there may be a chance the coastal regions of the Atlantic in England, North America and Europe could suddenly sea a sharp rise in ocean levels.

billiards

It would have to be a very rapid melting for the effects to be felt locally at the scale that you are discussing, and besides even if there were a great flood, it would soon disperse.