Why do sea levels rise when polar ice caps melt?

Question

I think it was Archimedes who found that when an ice cube is placed in a glass of water, the volume of water displaced is equal to the volume of water the ice cube will take up when melted. This means that the water level in the glass will stay constant even when the ice cube melts.

If this is true, then why does the earth's sea level rise as the polar ice caps are melting?

Surely the amount of water displaced by the ice caps will be equal to their volume once they melt and so the sea levels would stay constant.

Would someone please explain why the world's sea levels are rising???

Answer 1

This is a much more complex problem than a cup with an ice-cube.

Water at different temperatures has different densities and therefore, for the same mass different volumes. Even if the mass of the water in the oceans was constant (its not) the sea level could rise due only to increased temperature.

The mass of water in the oceans isnt constant:
Water is constantly flowing into the oceans, from rivers and streams. Lots of water.
Water is constantly flowing from one part of the oceans to another. Lots of water.
Water is constantly leaving the oceans, from evaporation. Lots of water.

This is a complex differential equation.

There are these things called aquifers, that have been being SERIOUSLY depleted, so that land areas the size of states are losing elevation, due do removed water. That water is being added to river water, and water in the air. Its being added into the system.

Although some glaciers are shrinking, by melting, some glaciers are growing. In Antarctica, the glaciers are growing. The parts breaking off, thats because so much new ice has formed that it pushes old ice into the ocean. Look to the alps to see what shrinking antarctic polar ice would look like.

So this is a system that is in very insanely complex motion. There are very hard to measure flows of things going in and out.

To conclusively attribute the rise in sea level to one and only one thing requires that you be able to accurately model the entire system, and measure the components of the entire system with high enough resolution to rule out any other plausible alternative. Weather guessers are only right to a few days out. That implies that the models, data, and computers are not perfect. I dont think anyone knows for certain why the ocean level is rising (if in fact it is).

Answer 2

Hi, you are absolotely right at your point that "the volume of water displaced is equal to the volume of water the ice cube will take up when melted. This means that the water level in the glass will stay constant even when the ice cube melts." Therefore, this means there are diffrent reasons.
One of them the glaciers that have been weakened by heat and broken off from their land into the sea. The more the temperature gets higher, the more glaciers fall into the oceans.
The second reason ; the density of the water is maximum at 4 degree, when the temperature gets higher , the degree of the water would go higher. Thus, this would reduce the density of the water and increse the volume ( m (mass) = d (density)* v( volume) . As a result of incresed water volume , the sea level would go up.
Hope to help you...

Answer 3

It's not the Arctic ice that's a problem---as you point out, all the floating Arctic ice could melt without raising the water level. It's all the ice in glaciers. In particular, it's Antarctica and Greenland. The Greenland ice cap is melting. The Antarctic ice cap may actually get bigger for a while as the Earth warms (usually it's "too cold to snow" in Antarctica), but eventually even Antarctica will melt, raising the sea level several hundred feet.

This may seem bad, but recollect that the sea level has risen 300 feet since the end of the last Ice Age 15,000 years ago, and there have been several periods in the last 500 million years when the Earth was largely ice-free. That's how you get fish fossils in Nebraska. ;-)

Answer 4

First of all, if you have ever frozen a bottle of liquid, you will know that it expands when it is frozen. It will take up less space when it melts.

Second, the polar ice caps are mostly out of the water. They are on land and flow into the ocean when they melt. The actual change of volume by the ice when it turns to water is irrelevant to this point.

Answer 5

The ice caps contain ice hundreds of feet above sea level, when this ice melts it flows into the oceans and the sea level rises

Answer 6

You are correct as to ice that is formed over water. If the ice is over land the melt will raise the sea level.

Answer 7

Because ice floats and when the ice melts that makes millions of gallons of water go flooding into the sea. quite simple actually.(and the sea has more than one ice cap,if you put six or seven ice cubes in a glass of water the water level WILL rise).:)

Answer 8

Global warming effects our sea levels because the globe get warmer. As we get warmer the polar ice caps begin to melt. When ice melts it becomes water and it mixes with everything else. our salinty levels will go down and our sea levels will go up.

Answer 9

When ice melts, it becomes water. Water makes it's way to the oceans. About the leveling its self out: the reason they are not it because they are melting at an alarming rate.

Ice only has be be a few degrees above freezing to melt, but has to be at least 100 degrees celcius to evaporate. It takes longer to evaporate than to melt.

Answer 10

Much of the polar ice is above the water.