[tlb]

A lot of it is in the glaciers of Antartica, which cover the whole continent with around 1900m of ice. They weren't created from seawater freezing, but from snow getting packed down. But the water will go into the ocean if they melt.

[oneoff786]

Ah ok that makes sense

[dhzhzjsbevs]

There isn't that much water on earth, this image does an amazing job of explaing the scale in the quickest way.

It also sort of explains how easy it would be for earth's water to have come from asteroid impacts.

https://d9-wret.s3.us-west-2.amazonaws.com/assets/palladium/...

[exitb]

By far most of the water is in the oceans, which have an average depth of 3688m. 2% of the water is currently frozen, so one can easily estimate how much would the sea level raise, had it all melt.

EDIT: Corrected km to meters, as comment below points out.

[ditn]

For those reading this with incredulity I believe the above commenter made a typo - the average depth is 3688m, or 12,100ft.

[oneoff786]

I’m not saying it’s wrong, but this graphic is very difficult for me to understand. Is there any geographical significance to the location of the water blobs? No, right? But they also don’t include saltwater which is most of it. Right?

[dhzhzjsbevs]

The big bubble is all water, frozen, sea, etc. The small bubble is all fresh (rain clouds etc), rivers, lakes. The smaller is lakes and rivers only.

Here's an article showing comparisons to various moon ice.

https://www.businessinsider.com/earth-water-ice-volume-versu...

[oneoff786]

It says liquid fresh water.

I don’t think the big bubble includes the ocean.

[progbits]

There are three bubbles.

[onlyrealcuzzo]

For reference, there's ~6.4M cubic miles of water in antarctica - and ~321M cubic miles of water in the ocean.

[JackC]

It's not the volume of the ocean that matters for sea level rise but the surface area, right? Ocean surface area is 140M square miles, so 6.4M cubic miles of water would naively be like a 241 foot rise -- each cubic mile gets split into 140/6.4 slices.

[Fuhrer01]

I'm a bit stupid, but I understand if we are dropping 6.4M cubic miles from space, there will be an increase in water level, but if the 6.4M cubic miles of water was already present in the system, just frozen, how does it increase the total sea level? There is no net change in volume right?

[exitb]

Antarctic glacier mostly rests on the continent, rather than float in the ocean.

[dredmorbius]

Land ice vs. sea ice.

Sea ice floats in the sea. When melted ... it's still floating in the sea, as water. There's no net sea-level change, at least not from contributed ice.[1]

Land ice sits on land. When it melts, most of it flows to the sea.[2] That increases the total amount of water in the oceans, and hence, sea level. The total rise if all Antarctic and Greenland ice melted would be about 60-70m (200-230ft).[3]

________________________________

Notes:

1. There are other effects, including thermal expansion (water expands slightly as it warms), and centripetal effects (water can flow more than continental crust does, and would spread out slightly more at the equator than the poles with more liquid water in the oceans). Those effects are comparatively small, though not fully negligible.

2. The exception would be enteric basins which have no outlet to the oceans, in which case melted ice flowing into these would form lakes. Examples of enteric basins include the Great Salt Lake and surrounding former Lake Bonneville, the Dead Sea, and Death Valley. Note that as glaciers melt, there's a rebound effect in continental crust, and regions presently below sea level or which would otherwise form enteric basins might not after that rebound effect is taken into account.

3. See: https://science.howstuffworks.com/environmental/earth/geophy... https://www.usgs.gov/faqs/how-would-sea-level-change-if-all-...

[dredmorbius]

Erm, that should be endorheic basins, not enteric, which has a different set of guts.

https://en.wikipedia.org/wiki/Endorheic_basin

https://en.wikipedia.org/wiki/Enteric

[tomrod]

Additionally the crust is elastic and will move around a bit (especially lifting) with the ice weight off. This is still occurring in many places that were glaciated previously.

[OJFord]

Fine as a rough approximation of course, but don't forget surface area will grow as sea level rises and threatens land.

[oneoff786]

I think that’s difficult to utilize for comprehending sea level. The relationship between total volume and sea level won’t be linear.

[nicoburns]

Surface area of the ocean would be more useful I think?