# How much of the Antarctic Ice Sheet is below sea level?

Hi Luke, thanks for your question!

An answer to your question can be found in the recent BEDMAP2 (an ice bed, surface, and thickness dataset for the Antarctic Ice Sheet) paper.

In terms of area:

5.50 x 10^6 km^2 (or 5,500,000 km^2) of ice is grounded below sea level.

The total area of the ice sheet is 12.295 x 10^6 km^2 (or 12,295,000 km^2).

Therefore, ~45% of the ice sheet, in terms of area, is grounded below sea level.

However, a great volume of ice remains above sea level. This ice, above flotation point, contains enough ice to raise global sea levels by 57.9 m.

### About Jacob Bendle

I am a Quaternary geologist with a focus on palaeo-ice sheet dynamics and palaeoclimate change during the last 20,000 years. I study glacial landforms to reconstruct glacier (and glacial lake) extents, dimensions and depositional processes. However, my main focus lies with the sedimentological analysis of annually-layered glacial lake sediments (known as varves) to develop continuous, high-resolution records of past ice sheet response to sub-centennial (rapid) climate shifts. Read more about me at https://www.antarcticglaciers.org/about-2/jacob-bendle/

### 15 thoughts on “How much of the Antarctic Ice Sheet is below sea level?”

1. R H Atkinson

If 45% of area is below sea level, I.e. submerged, then that VOLUME will be displacing & raising the world’s sea-level already.
Does this mean that it is only the ice above sea level which when melted, will raise world sea levels ?
I presume that this has been included in the calculations.

1. That’s pretty shady trying to convince people about a volumetric change by using a surface area calculation. You seem to have forgotten a whole dimension in your analysis. Who’s funding you for your fear mongering and false information? Fishing for government grants or something?

2. james Edward Tagge

No, a lesser impact. Ice is about 9 percent greater in volume than the quantity of water from which it grew. about 45 percent of the arctic caps are under water so if the caps melt, the water level of the oceans would remain about the same or rise very little. So much for climate alarmism.

1. Bethan Davies

Hello,
There is no ‘Arctic ice cap’. There’s the Greenland Ice Sheet, and the Arctic sea ice, but that’s not a grounded ice sheet, that’s floating, frozen sea water.
In Antarctica, the vast volume of ice above the level of the sea is what contributes to sea level. This amounts to almost 58 m of sea level rise, not including any ice below sea level.
Finally, a note: ice caps are small, less than 50,000 km^2. Ice sheets are larger than this. There are only two: the Antarctic Ice Sheet and the Greenland Ice Sheet.
So much for climate alarmism indeed.

1. Put Ice in a glass of water. When the ice melts the level will drop significantly. I think a ton of articles and so called expert studies leave this out. If the 45% of under water ice was double in size from expansion then if all the ice melted you would have nearly Zero change in water level.

1. Bethan Davies

In case I wasn’t clear enough, both the density difference between ice and water, and fin content in ice and snow, is taken into account when calculating sea level equivalents from ice volumes.

2. The article you linked explicitly states that ice below sea level is not taken into account, which is what the poster above you was presumably referencing. The article further provides a link describing how exactly this is calculated, but that link is inherently flawed. The author assumes that only ice above sea level can possibly contribute to rising sea levels, which is true. What he fails to account for completely is the fact that ice melting below sea level can only contribute to dropping sea levels. Hopefully we can correct this obvious error and arrive at a conclusion about our world’s ice melting that is closer to truth.

2. Stephen Daley

If water expands when it freezes and ~45% of sea ice is below sea level, then if it all melted, would it not occupy less space in the sea, lowering the sea level?

1. Bethan Davies

the frozen ice already displaces its volume in water, so the level will be the same. you can see this yourself when you melt ice cubes in a glass of water.

1. Again, you’re correct to say that the frozen ice displaces its volume in water. However, when ice melts, it displaces less volume in water, because ice (solid water) is less dense than liquid water. Therefore the level of water or the total volume of water decreases as ice melts, until all of the ice is gone and the volume begins to increase as the heat in the system increases, boiling the water. You can see this yourself when you melt ice cubes in a glass of water, just as you can easily see that the volume of water increases when you freeze a full bottle of water.

3. With antarctice temps around -37C no studies are suggesting the antarctice will contribute to a rise in sea levels in the forseeable future. Most have concluded the arctice contains insufficient ice to impact sea levels, only Greenland has a significant area of ice sheet. When you search it is not possible to get a percentage of ice that is above sea level & below sea level. This is crucial in determining any likely impact. That below sea level will contribute to a 9% decrease in ocean volume, whilst that above will add 91% of its volume to the sea, assuming sea level remains constant. Without this percentage it is by no means clear that melting all ice on earth will raise sea levels at all.

1. Laura Boyall

Hi Steve.

Actually, it is not just temperatures which result in the loss of ice and subsequent sea level rise in Antarctica. Whilst temperatures are well below freezing in most of the continent, the surrounding oceans are warming and this is what is causing much of the ice to calve and subsequently result in sea level rise. Antarctic ice melt is complex and not as straight forward as the Arctic where there is a linear relationship between warming temperatures and more ice melt.
If there is ice which is below sea level then the ice has already displaced the water, so unlike what you are referring to, it will not decrease the ocean volume it will simply stay the same.

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