'Inconvenient Truth' - "Sea Ice melting does not increase sea level" Is this true?

I ask because I thought it wasn’t.

He demonstrated by showing a single icecube melting versus a few in a glass.

The argument was that the single one was already underwater so levels won’t rise.

Two things…

Isn’t Ice denser than water? (So levels WILL rise when totally submerged ice melts?)

Sea-Ice isn’t totally submerged like the icecube. If it melts it ADDS the above sea ice to the water.

I know the bit of an iceberg you see is only ten percent of the actual size of the iceberg. ten percent is more than nothing.
Can you fight my ignorance?

Ice is actually less dense than water (that’s why it floats) - so melting sea ice will not raise the level of the water. Ice is also less dense than salt water, so it will not change the level of the sea. Only melting land ice or ice shelfs supported at the sea bottom can change the sea level.

No, ice isn’t denser then water, its less dense, otherwise it wouldn’t float

Gore is correct. Floating sea ice doesn’t add to the total level of water when it melts. Ice (or anything floating) displaces an amount of liquid water equal to its mass. When it melts, it turns into water, and so obviously continues to displace an amount of water equal to its mass. So there’s no change to the amount of water displaced and our sea level stays at the same place.

OK that’s that ignorance fought. It’s obvious now that I think about it.
Thanks :slight_smile:


Remember, though, that there is a LOT of shelf ice (ice that isn’t floating but is attached to land) and glaciers, especially in Greenland and Antarctica. That ice, when it melts, WILL raise sea levels because it’s not currently displacing the maximum amount of water that it could if it were actually floating. And it IS melting.

As I understand it it is a consequence of Archimedes’ Principle - an iceberg displaces a volume of water the mass of which is equal to the iceberg’s mass. That volume of volume of water raises the sea level by a height = displaced water volume divided by surface of the oceans.

When the iceberg melts it doesn’t displace water anymore but adds to the oceans’ water by the same volume.

About the 10% thing -

Look at it this way - the iceberg displaces an amount of water. If that amount of water that weighs enough to allow the iceberg to float has less volume than the iceberg - then the extra volume of the iceberg is left above the waterline.

If you were to magically increase the density of the ice, it would weigh more, and it would sink until weight of the water displaced by its volume equalled the weight of the iceberg. If it weighs so much that all the water displaced still does not equal the weight of the iceberg, then it sinks until it reaches a depth (the density of water does grow as depth increases - also as salt content increases or temperature decreases until about 4°C) where the weight of the water displaced equals the weight of the iceberg again. If there is no such depth, then the iceberg sinks all the way to the bottom.

Thanks wevets but I already grasped that when a previous poster mentioned displacement. But thanks anyway :slight_smile: