Displacing waterext_6140252August 17 2022, 07:33:05 UTC
> No, it is not about melting. It is about adding ice to the oceans, which adds mass. Archimedes' principle etc. Crystalline solids are a state of matter, a phase. It is irrelevant what phase the water is in; it's how much you add.
Another way of looking at it: It doesn't have to be water in any phase; add anything that has volume to the seas and the surface level will rise. If humans built and simultaneously launched ships with a mass equal to that ice shelf, those ships would also displace water (that's why the "mass" of a ship is more usually called "displacement") equal to that mass. And since, looking at all the oceans of the world as a whole, the water has nowhere to go but upwards, the surface level would rise by a total volume corresponding to that mass.
Given that the ice shelf wieghs, how many hundreds of billions of tons?, that's noticeable even when spread out over all the millions of square-kilometres of ocean surface. Of course that mass is pretty impossible to build... For mankind, as shipping. But not for nature, as mountain ranges or ice shelves or stuff.
(It's hard to imagine the Alps or the Himalayas toppling into the seas, and it wouldn't look exactly the same as ships or ice floes: The rock would lie at the bottom of the sea, not float on top of it. But put a stone in a kettle of water and the surface rises. Put a bunch of light and airy vegetables in your soup, and the surface also rises, even if the veggies float on top. Ice shelves may behave more like vegetables than like mountain ranges, but they'll make your kettle overflow all the same. :-)
Another way of looking at it: It doesn't have to be water in any phase; add anything that has volume to the seas and the surface level will rise. If humans built and simultaneously launched ships with a mass equal to that ice shelf, those ships would also displace water (that's why the "mass" of a ship is more usually called "displacement") equal to that mass. And since, looking at all the oceans of the world as a whole, the water has nowhere to go but upwards, the surface level would rise by a total volume corresponding to that mass.
Given that the ice shelf wieghs, how many hundreds of billions of tons?, that's noticeable even when spread out over all the millions of square-kilometres of ocean surface. Of course that mass is pretty impossible to build... For mankind, as shipping. But not for nature, as mountain ranges or ice shelves or stuff.
(It's hard to imagine the Alps or the Himalayas toppling into the seas, and it wouldn't look exactly the same as ships or ice floes: The rock would lie at the bottom of the sea, not float on top of it. But put a stone in a kettle of water and the surface rises. Put a bunch of light and airy vegetables in your soup, and the surface also rises, even if the veggies float on top. Ice shelves may behave more like vegetables than like mountain ranges, but they'll make your kettle overflow all the same. :-)
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But mountain ranges don't melt and dribble downhill, and if they did, we'd have bigger problems. Whereas ice does, and quite easily.
So, on a strict basis, yes, you are correct, but I am not sure it is a useful clarification in practical terms. :-)
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