If water expands when it freezes and ice contracts when it melts, shouldn’t icebergs/ice caps melting bring the water level down?



Especially since most of an iceberg is under water.

In: Physics

Sea ice melting doesn’t change the sea level, it’s already accounted for since it’s floating in the water.

The concern is that large volumes of glacier ice on Greenland and Antarctica will melt on land and then flow into the ocean.

A floating object displaces an amount of fluid equal to it’s weight.

Let’s say you have an iceberg that weighs 100,000 tonnes. It would displace 100,000 tonnes of water, and the rest of the iceberg would be above the water line.

If the iceberg were to completely melt, it would fill in exactly the amount of water it was displacing.

The problem with the melt is that not all the ice is floating. A lot of it is at least partially supported by land masses, whether it’s the Canadian Archipelago, or the Antarctican continent.

The problem is compounded that ice and snow reflect sunlight back out into space, whereas water will help to absorb sunlight. As we lose our polar caps, more of the sun’s light becomes absorbed by the Earth, so we gain that much more energy over time, causing more global average warming.

* There is lots of ice currently on land.
* When *that* ice melts, it runs into the ocean and raises sea levels.
* Also thermal expansion of water heating up causes the water to increase in volume which also increases sea levels.

You’ve also got a LOT of ice, even in icebergs but more in the poles, that while being frozen at the sea, reach for above sea level.

Don’t forget about all the ice we put into our coolers when we go boating it melts to and that gets poured into the water, who wants to carry the heavy cooler full of melted ice water back to the rig. 😋

Seen alot of comments about displacing of water etc so lets clear it up. Icebergs are only partially submerged in water (ocean) this means only the submerged part of the iceberg accounts for displacing water. However as the ice melts it does raise water levels as more water is being added. But if there is less ice as more of it turns to water then there will be less water being displaced by the ice. In short you are correct by your presumption in your question. What’s actually happening is the both are happening and are in constant battle over which process takes precedent, this only true for the short term (partial melting of the ice). However in the long term a complete melting of the iceberg would raise sea level, for example if you put ice in a glass of water and marked the water line then waited for it to melt you would see the water line would now be higher but only slightly. As the ice has already been technically speaking the top layer of ice has not been submerged which accounts for the extra gain in water when it has melted.

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