Where did the water come from in Antarctica?

  • Thread starter Columbo
  • Start date
  • #1
5
2
Sorry if this is a stupid question but I've searched google and I haven't found an answer. So I've been researching Antarctica and I've found a few details that don't add up. So supposedly if the ice melts on Antarctica then sea levels will rise by 200 feet - Antarctica contains 70% of earth's fresh water.

So here's where I'm having trouble finding out information. Supposedly 65 million years ago or so (I may be wrong on the numbers, but it doesn't matter), Antarctica was a hot place that had lush forests - then suddenly it got cold and turned into the Antarctica we know and love today. So where did the water come from? If the ice on Antarctica melted, then the sea levels would rise by 200 feet...if a few million years ago, Antarctica was hot then obviously it didn't contain anywhere near the amount of water it contains now...so where did all that water come from? Were the sea levels 200 feet higher than they are now in the past? Or did water evaporate from the rest of the lands around the world before being transported to Antarctica, then frozen and dumped there? When Antarctica was hot, where was that 70% of earth's fresh water stored?

Thank you so much in advance for any answers. It seems like such a basic question but I'm having real trouble finding an answer. So thank you very much for taking the time to read my silly question.

P.s a bonus follow up question. If the world does heat up and the ice on Antarctica melts, won't the increase in the temperature increase humidity thus causing more rain around the world? Instead of the seas rising, will all that extra water just get redistributed around the world as rain?
 
Last edited:

Answers and Replies

  • #3
5
2
I must be extra dumb because I've read that but it still doesn't answer my question - where was the fresh water originally? Were the sea levels 200 feet higher in the past and the ice came from the sea evaporating? Or was the world covered in much more fresh water that got redistributed and eventually fell on Antarctica as snow?
 
  • #5
phyzguy
Science Advisor
4,733
1,660
I think the simple answer to your question is, yes, the sea level was at least 200 feet higher before the antarctic ice sheet formed. Look at this graph from this Wikipedia page. 65 million years ago, sea level was about 150-200 meters higher than today

Phanerozoic_Sea_Level.png
 
  • Informative
  • Like
Likes pinball1970 and phinds
  • #6
Drakkith
Staff Emeritus
Science Advisor
21,100
4,933
Were the sea levels 200 feet higher in the past and the ice came from the sea evaporating?
That seems likely to me. I assume the water evaporated from the sea and was deposited on land by precipitation over the course of millions of years.
 
  • Like
Likes Steelwolf
  • #7
5
2
Thanks so much for the replies guys - trying to wade through all the conflicting data from the climate alarmists and the climate sceptics is proving to be impossible. It doesn't help that I'm pretty stupid to start with. At least I have one piece of the puzzle sorted, so thank you.
 
  • Like
Likes Tom.G and Nik_2213
  • #8
5
2
Skeptics. Skeptics. Not sceptics lmao...that was not an intentional freudian slip...
 
  • #9
PeroK
Science Advisor
Homework Helper
Insights Author
Gold Member
2020 Award
16,100
8,124
Skeptics. Skeptics. Not sceptics lmao...that was not an intentional freudian slip...
It's "sceptics" in British English. Not to be confused with "septic", as in "septic tank".
 
  • #10
5
2
It's "sceptics" in British English. Not to be confused with "septic", as in "septic tank".
Hahaha - what chance do I have of understanding the climate if I can't even spell lol :)
 
  • #11
BillTre
Science Advisor
Gold Member
2020 Award
1,688
3,948
Neither can I.
That's what spell checkers are for.
 
  • #12
62
70
When Antarctica was hot, where was that 70% of earth's fresh water stored?
Water cycle is the key here. It doesn't need to be stored as fresh water, it is the evaporation and raining cycle that produces fresh water, from the oceans.

P.s a bonus follow up question. If the world does heat up and the ice on Antarctica melts, won't the increase in the temperature increase humidity thus causing more rain around the world? Instead of the seas rising, will all that extra water just get redistributed around the world as rain?
Again, think about it like it is the water cycle, as a balance between water fluxes and what will happens if they are unbalanced. Increasing temperature increases both evaporation and condensation. When the storage capacity on land is entirely filled (lake, groundwater etc.), the sea levels won't change because raining and evaporation are balancing each other. The residence time of the water in the rivers are not long enough and the fluxes not big enough to mess with the balance.
 
  • #13
1
3
I think the simple answer to your question is, yes, the sea level was at least 200 feet higher before the antarctic ice sheet formed. Look at this graph from this Wikipedia page. 65 million years ago, sea level was about 150-200 meters higher than today

View attachment 250211
Water cycle is the key here. It doesn't need to be stored as fresh water, it is the evaporation and raining cycle that produces fresh water, from the oceans.



Again, think about it like it is the water cycle, as a balance between water fluxes and what will happens if they are unbalanced. Increasing temperature increases both evaporation and condensation. When the storage capacity on land is entirely filled (lake, groundwater etc.), the sea levels won't change because raining and evaporation are balancing each other. The residence time of the water in the rivers are not long enough and the fluxes not big enough to mess with the balance.
Some things to consider. Only ice that is not floating on oceans would be able to raise ocean levels. As we know ice floats because it expands. Once it melts it returns to the same volume the ice displaced (why your glass doesn't overflow when it has a lot of ice in it.
The average temp in Antarctica is -10 to -60 centigrade from near the coast to the coldest place, so it would take at least 10 degrees of warming to start melting and I understand that is way below present predictions. http://www.antarctica.gov.au/about-antarctica/environment/weather.
We would also have to know the land mass created by the plates at the time of the highest ocean rise. Does anyone know how much land mass there was when the oceans rose 200 ft higher.Obviously, more land mass, higher ocean.
Finally, how much water was actually on the earth, as I understand we gradually are losing water to space, just like, but not nearly as fast as Mars did. Is that significant?
 
  • #14
Drakkith
Staff Emeritus
Science Advisor
21,100
4,933
as I understand we gradually are losing water to space, just like, but not nearly as fast as Mars did. Is that significant?
No, it is an insignificant amount over even long geological times.
 
  • #15
Baluncore
Science Advisor
8,644
3,317
Does anyone know how much land mass there was when the oceans rose 200 ft higher.Obviously, more land mass, higher ocean.
It does not really work that way. Earth's thin crust floats on the fluid mantle.

One effect is that when sea level is raised 4 metres, the added weight of water on the sea floor would push that down by about one metre, leaving a 3 metre difference on the coast. But pushing the oceans down lifts the land, which gives back more than a metre because there is more area of sea than land, so it lifts the mountains slightly. That is called isostasy.

The real problem is finding something solid to measure sea level against.
https://en.wikipedia.org/wiki/Isostasy#Isostatic_effects_of_ice_sheets
 
  • Like
Likes Bystander and Drakkith
  • #16
479
252
It does not really work that way. Earth's thin crust floats on the fluid mantle.
It is misleading to describe the mantle as fluid. The mantle is solid, bar isolated pockets where partial melting produce a small proportion (generally less than 10%) of magma.

The uppermost portion of the mantle is rigid and, with the overlying crust, forms the lithosphere. Below that lies the asthenosphere, which temperature and mineralogy render ductile. This is what responds isostatically to fluctuating loads from ice, rock and water.
 
  • Like
Likes BillTre
  • #17
Baluncore
Science Advisor
8,644
3,317
It is misleading to describe the mantle as fluid.
I am talking about the longer isostatic time scale. I would agree that the mantle is a very viscose fluid, but it only has to move 10 cm per year, enough to allow for continental drift, and isostasy.
 
  • #18
20
14
The average temp in Antarctica is -10 to -60 centigrade from near the coast to the coldest place, so it would take at least 10 degrees of warming to start melting and I understand that is way below present predictions. http://www.antarctica.gov.au/about-antarctica/environment/weather.
There is more to melting Antarctic ice than simply warming it up in situ. In simple terms: Antarctica is a very high plateau of ice which gradually flows to the ocean via the very extensive network of glaciers. The glacial ice melts (slowly) on contact with the ocean. As the ocean warms the rate of melting increases, particularly on the underside of the glacial tongues. In turn this leads to glaciers which are less "grounded" and hence flow faster. This in turn means that Antarctica loses ice. And you know where that leads...
Cheers
Ian
 

Related Threads on Where did the water come from in Antarctica?

Replies
39
Views
34K
Replies
2
Views
7K
  • Last Post
Replies
9
Views
17K
Replies
6
Views
3K
Replies
7
Views
5K
Replies
1
Views
3K
  • Last Post
Replies
3
Views
15K
  • Last Post
Replies
2
Views
4K
  • Last Post
Replies
12
Views
1K
  • Last Post
Replies
8
Views
3K
Top