# B Archimedes and sea level rise

#### solarmidnightrose

Summary
the displacement of water and its possible connection to the claims made about climate change.
I'm pretty sure that everyone knows that if you put an ice cube in a cup of water, and leave it for some time for the ice to melt, the level of water in the glass will not rise. (you could use that principle where that guy was in the tub and said "Eureka!" and then ran around naked).

Now, my question is that with all this climate change business on the news, etc... is it correct for people to say that the ice-caps are melting and are causing the sea levels to rise? I mean, the ice-caps were already in the water, and so if they melt, would it cause a rise in the sea levels?

I'm really curious.

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#### 256bits

Gold Member
What if you had an ice cube floating in salt water, and the ice cube melted.
Would the water level in the glass stay the same, rise or lower?

#### PeroK

Homework Helper
Gold Member
2018 Award
Summary: the displacement of water and its possible connection to the claims made about climate change.

I'm pretty sure that everyone knows that if you put an ice cube in a cup of water, and leave it for some time for the ice to melt, the level of water in the glass will not rise. (you could use that principle where that guy was in the tub and said "Eureka!" and then ran around naked).

Now, my question is that with all this climate change business on the news, etc... is it correct for people to say that the ice-caps are melting and are causing the sea levels to rise? I mean, the ice-caps were already in the water, and so if they melt, would it cause a rise in the sea levels?

I'm really curious.
You should do some research on this. For example:

#### solarmidnightrose

What if you had an ice cube floating in salt water, and the ice cube melted.
Would the water level in the glass stay the same, rise or lower?
Ok, the water level would rise; because of the differing densities of the substances.
I guess I should have thought more about that before posting this.

Thanks for opening my eyes:)

#### solarmidnightrose

You should do some research on this. For example:

Yeah, I realised my mistake a couple of minutes after posting this.

At the time I just posted my question without actually doing any research myself (you know those moments when you're just thinking about something & the obvious is right in front of you but you can't see it?.... that's what I just did).

Thanks though for your input :)
The link was very informative, thanks.

#### Nugatory

Mentor
I mean, the ice-caps were already in the water
Neither the Greenland nor the Antarctic ice sheets are already in the water.

#### solarmidnightrose

Neither the Greenland nor the Antarctic ice sheets are already in the water.
Yeah, sorry about that @Nugatory . I wasn't thinking properly (I guess I was writing things down rather impulsively and without much thought).

Originally, I was thinking about the land (which has the ice sheets on it) being in the water and what effect the melting of the ice sheets would have on the water level. But I've realised some other points that needed to be considered from previous answers to my question.

Thanks for pointing it out though-really helped with further cementing the idea into my head :)

#### sophiecentaur

Gold Member
I heard that substantial loss of ice mass on land would result on the land rising due to reduced load. That could lead to further lowering of sea beds and some land levels. More potential problems.

#### zanick

another factor for sea level rise is the rising and moving ocean floor and land masses that encompass the oceans. it is safe to say that they are constantly in motion rising and falling which is a much greater factor than the sea level rise due to melting icecaps, that are not floating already on the ocean. (north pole melt, besides greenland is floating). sea level rise has always been near 7" per 100 years and this rate doesnt seem to be changing. and if it did, there could be many other factors rather than sea ice melting. the density differnce of sea water to fresh water a fairly minor component 2% the density of the sea water is a non factor, as Archimedes proved. fresh water floating on the sea water will displace exactly the same amount of sea water as it melts, even if it had millions of kg of gold sitting on top!!!!!

#### zanick

What if you had an ice cube floating in salt water, and the ice cube melted.
Would the water level in the glass stay the same, rise or lower?
the water level would stay the same... unless you know something i dont. the buoyant force will equal the weight of the medium it displaced .

#### Nugatory

Mentor
the water level would stay the same... unless you know something i dont. the buoyant force will equal the weight of the medium it displaced .
Does it matter whether the ice cube is frozen salt water or fresh?

#### sophiecentaur

Gold Member
Does it matter whether the ice cube is frozen salt water or fresh?
The process of freezing tends to leave you with more or less pure ice and the salt goes into the seawater underneath, I think. That's not to say that the ice is totally pure because salt can be trapped in gaps between the ice crystals.

"Archimedes and sea level rise"

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