<p><strong>A first-order estimate is about 5%.</strong></p>

<p>This is a trickier question than it first appears because of ice shelves. Quoting from Kusky (2014):</p>

<blockquote>
  <p>Ice shelves form where ice sheets move over ocean waters and form a thick sheet of ice floating on the water and attached to the land on one, two, or three sides. Their seaward sides are typically marked by a steep cliff up to 1500 ft (500 m) high, where many glaciers calve off from forming icebergs.</p>
</blockquote>

<p>So they are floating, and they can be up to 2000 m thick, according to <a href="http://www.antarcticglaciers.org/glaciers-and-climate/shrinking-ice-shelves/ice-shelves/" rel="nofollow">antacticglaciers.org</a>. So they definitely make a substantial contribution to the world's sea ice fraction.</p>

<p>Continuing with Kusky:</p>

<blockquote>
  <p>Ice shelves are found in Antarctica, Greenland, and along the polar seacoasts of the Canadian Arctic Islands. The largest ice shelves are contained in Antarctica, which contains 91% of the world's glacial ice, around 7% of which is contained in ice shelves. These ice shelves cover 50% of the coast of Antarctica, forming an area 1/10th the size of the continent.</p>
</blockquote>

<p>If you don't take ice shelves into account, and only think about pack ice, you end up with about 0%, because <a href="https://en.wikipedia.org/wiki/Arctic_ice_pack" rel="nofollow">pack ice</a> is generally thinner than about 4 m, and so makes up a tiny fraction of global ice volume, in spite of its extensive area.</p>

<p>But if you do account for ice shelves, especially <a href="https://en.wikipedia.org/wiki/List_of_Antarctic_ice_shelves" rel="nofollow">the southern ones</a>, the answer must be much greater. I have not done the research to find the numbers, but the text I quoted suggests something less than 7%, so I'm going with 5% as a first-order, round-number guess.</p>

<p><strong>Reference</strong></p>

<p>Kusky, T M (2014), Encyclopedia of Earth Science, New York Academy of Sciences, 529 pp. <a href="https://books.google.ca/books?id=p1Bs03rhZzwC&amp;lpg=PA359&amp;ots=-bg67Yned2&amp;pg=PA359#v=onepage&amp;q&amp;f=false" rel="nofollow">In Google Books.</a></p>

CC BY-SA 3.0
2016-05-07T11:18:27.140Z
2016-05-09T11:37:14.713Z
2016-05-09T11:37:14.713Z
Matt Hall
<p>The Antarctic land ice averages a little over 1.8 kilometres thick. Greenland  ice averages a bit more than 2 kilometres thick. The circum-Antarctic ice thickness averages only between 1 and 2 metres in thickness, whilst the Arctic (all sea ice) varies between 1 and 5 metres thick - it was >6 metres thick but global warming has been thinning the ice in recent decades.</p>

<p>At its maximum winter extents the sea ice is comparable in area to the continental ice, so the fraction of global floating ice is about 0.1%. If you need a more accurate answer then I suggest you trawl the internet for areal extents, and do a seasonal mass balance. Obviously, it will vary according to which hemispheric winter you choose. 
I suggest 'Arctic Sea Ice News' <a href="https://nsidc.org/arcticseaicenews/" rel="nofollow">https://nsidc.org/arcticseaicenews/</a> as a good starting point.</p>

CC BY-SA 3.0
2016-05-07T10:46:35.757Z
2016-05-07T10:46:35.757Z
Gordon Stanger
<p>How much of the ice on Earth is floating (such as icebergs, or perhaps all the ice up at the North Pole)? </p>

CC BY-SA 3.0
2016-05-06T14:17:23.430Z
You may notice similarities to this question: http://earthscience.stackexchange.com/questions/7228/how-much-of-earths-surface-would-be-covered-by-water-if-all-ice-melted 

However, that question was never answered and seems to be populated by people who can't decide how take a percent of a percent.
jhch
CC BY-SA 3.0
2016-05-06T17:02:35.787Z
Good question. There are quite a few data sources. [This](http://www.johnstonsarchive.net/environment/waterworld.html), and its sources, seems like a place to start.
Matt Hall
CC BY-SA 3.0
2016-05-06T18:41:02.293Z
Do you mean mass/volume, or surface area?
jamesqf
CC BY-SA 3.0
2016-05-07T02:21:11.887Z
@kwinkunks that seems like a terrible place to start. Isn't the site about earth *science*?
mankoff
CC BY-SA 3.0
2016-05-07T10:55:15.030Z
@mankoff Fair enough, I only really looked at that table and the references, which don't seem too bad. I was really just trying to encourage the OP to do some research of their own, to make the question more pointed. The point is that there are a lot of resources out there for the person to do a little work of their own.
Matt Hall
<ice-sheets><ice><cryosphere>
How much of the ice on earth is floating?
jhch
# How much of the ice on earth is floating?

(Asked by: username_0 on 2016-05-06)

How much of the ice on Earth is floating (such as icebergs, or perhaps all the ice up at the North Pole)?

**Tags:** ice-sheets, ice, cryosphere

> **Comments:**
> **username_0**: You may notice similarities to this question: http://earthscience.stackexchange.com/questions/7228/how-much-of-earths-surface-would-be-covered-by-water-if-all-ice-melted   However, that question was never answered and seems to be populated by people who can't decide how take a percent of a percent.  
> **username_1**: Good question. There are quite a few data sources. [This](http://www.johnstonsarchive.net/environment/waterworld.html), and its sources, seems like a place to start.  
> **username_2**: Do you mean mass/volume, or surface area?  
> **username_3**: @kwinkunks that seems like a terrible place to start. Isn't the site about earth *science*?  
> **username_1**: @username_3 Fair enough, I only really looked at that table and the references, which don't seem too bad. I was really just trying to encourage the OP to do some research of their own, to make the question more pointed. The point is that there are a lot of resources out there for the person to do a little work of their own.  

---

## 2 answers

### Answer by username_1 on 2016-05-07. Score: 7

**A first-order estimate is about 5%.**

This is a trickier question than it first appears because of ice shelves. Quoting from Kusky (2014):

> Ice shelves form where ice sheets move over ocean waters and form a thick sheet of ice floating on the water and attached to the land on one, two, or three sides. Their seaward sides are typically marked by a steep cliff up to 1500 ft (500 m) high, where many glaciers calve off from forming icebergs.

So they are floating, and they can be up to 2000 m thick, according to [antacticglaciers.org](http://www.antarcticglaciers.org/glaciers-and-climate/shrinking-ice-shelves/ice-shelves/). So they definitely make a substantial contribution to the world's sea ice fraction.

Continuing with Kusky:

> Ice shelves are found in Antarctica, Greenland, and along the polar seacoasts of the Canadian Arctic Islands. The largest ice shelves are contained in Antarctica, which contains 91% of the world's glacial ice, around 7% of which is contained in ice shelves. These ice shelves cover 50% of the coast of Antarctica, forming an area 1/10th the size of the continent.

If you don't take ice shelves into account, and only think about pack ice, you end up with about 0%, because [pack ice](https://en.wikipedia.org/wiki/Arctic_ice_pack) is generally thinner than about 4 m, and so makes up a tiny fraction of global ice volume, in spite of its extensive area.

But if you do account for ice shelves, especially [the southern ones](https://en.wikipedia.org/wiki/List_of_Antarctic_ice_shelves), the answer must be much greater. I have not done the research to find the numbers, but the text I quoted suggests something less than 7%, so I'm going with 5% as a first-order, round-number guess.

**Reference**

Kusky, T M (2014), Encyclopedia of Earth Science, New York Academy of Sciences, 529 pp. [In Google Books.](https://books.google.ca/books?id=p1Bs03rhZzwC&lpg=PA359&ots=-bg67Yned2&pg=PA359#v=onepage&q&f=false)


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### Answer by username_4 on 2016-05-07. Score: 0

The Antarctic land ice averages a little over 1.8 kilometres thick. Greenland ice averages a bit more than 2 kilometres thick. The circum-Antarctic ice thickness averages only between 1 and 2 metres in thickness, whilst the Arctic (all sea ice) varies between 1 and 5 metres thick - it was >6 metres thick but global warming has been thinning the ice in recent decades.

At its maximum winter extents the sea ice is comparable in area to the continental ice, so the fraction of global floating ice is about 0.1%. If you need a more accurate answer then I suggest you trawl the internet for areal extents, and do a seasonal mass balance. Obviously, it will vary according to which hemispheric winter you choose.
I suggest 'Arctic Sea Ice News' <https://nsidc.org/arcticseaicenews/> as a good starting point.


---

