Talk:Geography of Antarctica

Removed U.S. comparison

Removes from Antarctica article:

Area - comparative: slightly less than 1.5 times the size of the US

I took that out because it seems to suggest Wikipedia is a U.S. publication, which it isn't, it is a worldwide encyclopedia. Besides, of those who don't live in the U.S., how many know the area it consumes? The United States is not the centre of the universe, you know. - Mark Ryan

So what can we compare areas to that won't be equally arbitrary? Or do we just state them in units (km^2 or mile^2)? Pakaran (ark a pan) 18:19, 11 Nov 2004 (UTC)

Oy. We REALLY need to cut down the size of this map! -- Zoe

Ice sheet concern

There has been some concern about this Ice sheet, because there is a small chance that it will collapse. If it would do so, ocean levels would rise by a few metres in a very short period of time.

Who is concerned? People who don't know that the ice sheet is on land and has no where to collapse into? Or people who don't know that floating ice, when it breaks off, does NOT displace any more water? (Because it's ALREADY floating) --user:Ed Poor (deep or sour) 17:44, Nov 11, 2004 (UTC)

Shelf and sheet

Wikipedia says:

Ice Shelves float on the surface of the sea and, if they melt, to first order they do not change sea level. Because they are fresh, however, their melting would cause a small increase in sea levels. It can also be argued that if ice shelves melt it is a precursor to the melting of ice sheets on Greenland and Antarctica. [1]

(William M. Connolley 21:16, 11 Nov 2004 (UTC)) OK, lets try to straighten this nonsense out.

Western Antarctica is covered by the West Antarctic Ice Sheet. There has been some concern about this Ice sheet, because there is a small chance that it will collapse. If it would do so, some people worry that ocean levels would rise by a few metres in a very short period of time. However, ice Shelves float on the surface of the sea and, if they melt, to first order they do not change sea level (see Sea level rise).

The para is above, Eds addition in italics. Ed's additions make it wrong, and hence I have removed them. Ice shelves float. Ice sheets don't. If the WAIS collapses it *will* cause a large sea level rise. There is no case for qualifying this by 'some people worry that'. What should be qualified (and it is, with "small probability") is the chances of the WAIS collapsing. The wiki entry Ed quotes was written by me and is therefore correct. As a fig leaf, I've just done a minor edit to it to emphasise that the SRL from ice shelves is very small indeed. But in the disputed para, we're not talking shelves we are talking sheets.

Is that clear now?

The wiki entry Ed quotes was written by me and is therefore correct. LOL! I give up; how can I dispute the same source I just cited? :-) --user:Ed Poor (deep or sour) 21:25, Nov 11, 2004 (UTC)

We do need to point out that any collapse would not happen overnight and result in disaster-movie-like scenes. I don't know if the article makes that clear. Pakaran (ark a pan) 23:38, 11 Nov 2004 (UTC)

(William M. Connolley 09:42, 12 Nov 2004 (UTC)) But does that belong on geography of ant?

Prolly not, sorry. Pakaran (ark a pan) 10:57, 12 Nov 2004 (UTC)

See polar ice and especially sea ice. Then somebody try to find a definitive scientific answer to the following question:

• What happens when an ice shelf "calves off" from an ice sheet? Does it sink? How fast does it sink? Does it create a tsunami?

Here's my Official Layman's Answer:

• Nothing at all happens. The ice is already floating, with 90% underwater and buoying up the 10% that's above water. All you get is a huge iceberg the size of Rhode Island -- which has happened several times before and was photographed by satellites and tracked by the US government ice-watching agency (no, Dr. C., not a "survey")

Eventually, the iceberg drifts north and melts, which reduces the saline content of the world's oceans! But let's ask Dr. C. if this reduction is computable or even significant. --user:Ed Poor (deep or sour) 17:02, Nov 12, 2004 (UTC)

Here's what Scientists Who Study Ice say:

The breakup of the ice shelves in the Peninsula has little consequence for sea level rise. [2]

And Dr. C.'s mates say:

Reports of melting ice sheets threatening to raise sea levels, global warming and climate change pervade the mass media and spread concern among governments and public alike. However, the timing and causal links between changes in the Antarctic ice sheet and other features of the global system such as atmosphere, oceans and land masses are neither simple nor direct. [3]

and since their models aren't any good they surveyed a dozen scientists for a report on the Risk of collapse of the Antarctic ice sheet, which concluded that:

it is most likely that in the near future the Antarctic ice sheet will reduce, or mitigate, sea level rise. [4]

(William M. Connolley 17:56, 12 Nov 2004 (UTC)) All of the quotes you provide above are from real scientists and are therefore correct :-). The problem is that you have misunderstood them. You also still haven't understood ice shelves. Ice shelves are where the ice sheet flows off into deeper water. If an ice shelf melts it has little direct impact on sea level. It might cause an indirect effect by increasing flow from the grounded ice sheet, which would increase sea level. The mitigation of SRL is true, of course: its in IPCC. There is no controversy about it. Its just that the effect is much smaller than thermal expansion.

Volcanoes of Antarctica

I note that the article mentions that Paulet Island and Lindenberg Island are regarded as active volcanoes. I am not sure about Paulet Island, but the activity of Lindenberg Island is based on a report by Nordenskjold (1902) which was not confirmed by later expeditions, and is now suspected of being erroneous. I will check this out when I have a chance, but I am pretty sure that (despite being marked as active on the "Tectonic Map of the Scotia Arc") Lindenberg island is not active. --APRCooper (talk) 21:06, 1 January 2008 (UTC)

Depression of land

The article says: "the ice is so massive that it has depressed the continental bedrock in some areas more than 2.5 km below sea level". Even granted that the bedrock is indeed 2.5 km below sea level, what is this statement supposed to imply? That the bedrock would be above sea level if the ice were not there? That the bedrock would be, perhaps, only 2 km below sea level if the ice were not there? Backspace (talk) 04:27, 22 January 2008 (UTC)

The weight of the ice is pushing the rock down; the crust of the Earth is pushed down into the space where the upper mantle would otherwise be. See Isostatic depression and isostatic rebound for what happens when the weight is removed. -- SEWilco (talk) 04:43, 22 January 2008 (UTC)

Oh.. the article already has a copy of the latter link. -- SEWilco (talk) 04:48, 22 January 2008 (UTC)

Well, those articles explain a lot of things that I didn't know, but I'm still trying to get a general idea of how Antarctica would look if the ice were removed, both immediately, and with respect to the forces in those linked articles, at eventual equilibrium, i.e., which parts would be under water and which parts would be land. Backspace (talk) 07:50, 22 January 2008 (UTC)

Natural resources

I am a little unhappy about the fact box listing minerals as natural resources, for the following reasons. First, there are no PROVEN mineral resources in Antarctica at all. Of course, given the size of the continent, it is very likely that they exist, but at present there are no proven resources. Second, there is a moratorium on mineral exploitation, so no mineral resources can be proven for the foreseeable future. Thirdly, as less than 0.5% of the continent is accessible to geological exploration (the rest is covered in ice averaging nearly 2km thick), the commercial constraints on exploitation make it unlikely that minerals could be extracted commercially. Studies have been done on this last point and it has been shown that it would be uneconomic to exploit a resource of the value of the Bushveld Complex in South Africa if it were in Antarctica.

Note that there is a big difference between noting the presence or absence of a mineral and it's being present in exploitable quantities. For example, deposits of coal are found in the Transantarctic Mountains, and these have been known since the days of Scott's expeditions. However, there is no evidence that the coal is present in exploitable quantities, and given the tectonic setting it is probably unlikely that it is.

If there is no response to this, I will remove the minerals from the Natural Resources box.--APRCooper (talk) 10:41, 22 February 2008 (UTC)

OK, there was no response by the end of the day, so I've done the change. --APRCooper (talk) 17:08, 22 February 2008 (UTC)

The continent does have a large amount of water, but that's already mentioned somewhere. If there are known amounts of minerals they'll get listed, just as some articles list tar sands and other presently unusable resources. It's easy to do the math and know there is a lot of something in any continent, but here we need to know what specific deposits have been found. Yes, some coal is known, but we'd need to know whether it is an isolated deposit or one which extends for hundreds of kilometers. -- SEWilco (talk) 17:46, 22 February 2008 (UTC)

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