# Global warming and a rise in water levels from arctic ice melts
**URL:** https://boards.straightdope.com/t/global-warming-and-a-rise-in-water-levels-from-arctic-ice-melts/5747
**Category:** Factual Questions
**Created:** [December 31, 1999, 9:20pm UTC](https://boards.straightdope.com/t/global-warming-and-a-rise-in-water-levels-from-arctic-ice-melts/5747 "1999-12-31T21:20:00Z")
**Posts on this page:** 20
**Page:** 1
### Author:  [@threemae](https://boards.straightdope.com/u/threemae)
#### Post date: [December 31, 1999, 9:20pm UTC](https://boards.straightdope.com/t/global-warming-and-a-rise-in-water-levels-from-arctic-ice-melts/5747/1 "1999-12-31T21:20:00Z")
Back in fourth grade (five short years ago) I went through all of the liberal, tree hugging drivel about global warming. One of the things that our teachers repeated about global warming was that sea levels would rise if the arctic ice cap melted. This makes perfect sense for the antarctic ice cap, but applying the rules of buoyancy absolutely no sense for the arctic ice cap. Additionally, how long would it take for the polynesian islands to adust to the water level if the antarctic ice cap melted in 30 years? Assuming the level of the impovrished beaches are some sort of function of sea level, would not the beaches adjust to the new sea level?
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You know, doing what is right is easy. The problem is knowing what is right.
–Lyndon B. Johnson
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### Author:  [@Soup](https://boards.straightdope.com/u/Soup)
#### Post date: [December 31, 1999, 10:03pm UTC](https://boards.straightdope.com/t/global-warming-and-a-rise-in-water-levels-from-arctic-ice-melts/5747/2 "1999-12-31T22:03:00Z")
I think the ice in the Artic and Antartic are both affected in the global warming scenarios I’ve read. Ice is ice, it’s going to melt if it gets hot. As far as those Polynesian islands are concerned: sure, their beaches will change shape and creep inland, depending on the rate of the ocean’s rise, erosion, etc. But those islands aren’t floating on the surface of the ocean, they’re the top of an underwater land mass. When the ocean rises high enough, they’ll be submerged.
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### Author:  [@Soup](https://boards.straightdope.com/u/Soup)
#### Post date: [December 31, 1999, 10:05pm UTC](https://boards.straightdope.com/t/global-warming-and-a-rise-in-water-levels-from-arctic-ice-melts/5747/3 "1999-12-31T22:05:00Z")
And just so I don’t get a note from your teacher: ARCTIC and ANTARCTIC
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### Author:  [@Ike\_Witt](https://boards.straightdope.com/u/Ike_Witt)
#### Post date: [January 1, 2000, 12:00am UTC](https://boards.straightdope.com/t/global-warming-and-a-rise-in-water-levels-from-arctic-ice-melts/5747/4 "2000-01-01T00:00:00Z")
The change to the Pacific Islands could be very dramatic. 30,000 bp the Bismarck sea in Melanesia was about 50m lower than it is today. It is assumed that many islands that were inhabited during the human migration into the pacific were submerged.
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### Author:  [@Fleetwood](https://boards.straightdope.com/u/Fleetwood)
#### Post date: [January 1, 2000, 12:07am UTC](https://boards.straightdope.com/t/global-warming-and-a-rise-in-water-levels-from-arctic-ice-melts/5747/5 "2000-01-01T00:07:00Z")
Adamyak: I get the 50m (Fifty meters) but what the heck is 30,000bp referring to?
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### Author:  [@Fleetwood](https://boards.straightdope.com/u/Fleetwood)
#### Post date: [January 1, 2000, 12:07am UTC](https://boards.straightdope.com/t/global-warming-and-a-rise-in-water-levels-from-arctic-ice-melts/5747/6 "2000-01-01T00:07:00Z")
Sorry, Adam yak.
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### Author:  [@Fleetwood](https://boards.straightdope.com/u/Fleetwood)
#### Post date: [January 1, 2000, 12:08am UTC](https://boards.straightdope.com/t/global-warming-and-a-rise-in-water-levels-from-arctic-ice-melts/5747/7 "2000-01-01T00:08:00Z")
Sorry sorry adam yax
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### Author:  [@threemae](https://boards.straightdope.com/u/threemae)
#### Post date: [January 1, 2000, 12:26am UTC](https://boards.straightdope.com/t/global-warming-and-a-rise-in-water-levels-from-arctic-ice-melts/5747/8 "2000-01-01T00:26:00Z")
BP=Before present
What I was asking was if the beeches might eventually rise. Many of these islands are relatively flat and these islands do not just happen to be precisely the correct height. Soup, want to think about that note from my teacher?
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You know, doing what is right is easy. The problem is knowing what is right.
–Lyndon B. Johnson
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### Author:  [@Ike\_Witt](https://boards.straightdope.com/u/Ike_Witt)
#### Post date: [January 1, 2000, 12:36am UTC](https://boards.straightdope.com/t/global-warming-and-a-rise-in-water-levels-from-arctic-ice-melts/5747/9 "2000-01-01T00:36:00Z")
If the polar cap melts many islands and atolls will simply vanish, other with high enough peaks will survive at just a fraction of their current size. Also, most coastal cities will be flooded.
But I’m not sure what you are getting with rising beaches.
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### Author:  [@threemae](https://boards.straightdope.com/u/threemae)
#### Post date: [January 1, 2000, 1:30am UTC](https://boards.straightdope.com/t/global-warming-and-a-rise-in-water-levels-from-arctic-ice-melts/5747/10 "2000-01-01T01:30:00Z")
The current height of many islands in the Pacific is virtually right at sea level. These islands obviouly did not just happen to randomly arrive perfectly at the current sea level, so the height of islands must be some sort of function of sea level. What I am asking is if the sea level rising would cause the islands to rise some level.
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You know, doing what is right is easy. The problem is knowing what is right.
–Lyndon B. Johnson
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### Author:  [@Cooper](https://boards.straightdope.com/u/Cooper)
#### Post date: [January 1, 2000, 2:01am UTC](https://boards.straightdope.com/t/global-warming-and-a-rise-in-water-levels-from-arctic-ice-melts/5747/11 "2000-01-01T02:01:00Z")
You are right, height is a function of sea level, but this applies only during the volcanic formation of the island. When the ice caps melt and the oceans cover these islands, they will be gone (unless they have active volcanoes, in which case we might see islands there again someday.)
Incidentally, although the liberal watermelons (green on the outside, pink on the inside!) yammer a lot about global warming etc, it is an accepted fact that global temperatures this decade have been the highest in thousands of years - as far back as we can tell it has never been this hot. Global warming is an accepted fact, the only debate concerns exactly what causes contribute to it and how much, and what we can do about it.
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### Author:  [@Doobieous](https://boards.straightdope.com/u/Doobieous)
#### Post date: [January 1, 2000, 3:12am UTC](https://boards.straightdope.com/t/global-warming-and-a-rise-in-water-levels-from-arctic-ice-melts/5747/12 "2000-01-01T03:12:00Z")
Threemae: Most of the atolls in the pacific are made of coral sands. Atolls are rings of coral islands surrounding a highly eroded volcano (or in some cases, a completely eroded volcano). They sand is of course created by wave action at the edges of the atolls and the sand is carried inward. If the sea level rises, the coral may survive, but the islands wont be inhabitable until the coral grows up to sea level, and waves form new sands.
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### Author:  [@threemae](https://boards.straightdope.com/u/threemae)
#### Post date: [January 1, 2000, 3:43am UTC](https://boards.straightdope.com/t/global-warming-and-a-rise-in-water-levels-from-arctic-ice-melts/5747/13 "2000-01-01T03:43:00Z")
Thank you Cooper and Doobeous, your answers explaind the question pretty well. I take it the answer is quite a long tme.
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You know, doing what is right is easy. The problem is knowing what is right.
–Lyndon B. Johnson
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### Author:  [@Doobieous](https://boards.straightdope.com/u/Doobieous)
#### Post date: [January 1, 2000, 3:01pm UTC](https://boards.straightdope.com/t/global-warming-and-a-rise-in-water-levels-from-arctic-ice-melts/5747/14 "2000-01-01T15:01:00Z")
Here’s an interesting bit of trivia I heard on one of the Millennium celebration shows yesterday, most of the atolls in the pacific didnt exist 1,000 years ago (so the broadcaster said).
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### Author:  [@Ike\_Witt](https://boards.straightdope.com/u/Ike_Witt)
#### Post date: [January 3, 2000, 2:01pm UTC](https://boards.straightdope.com/t/global-warming-and-a-rise-in-water-levels-from-arctic-ice-melts/5747/15 "2000-01-03T14:01:00Z")
Cooper,
> [@](#):
>
> it is an accepted fact that global temperatures this decade have been the highest in thousands of years - as far back as we can tell it has never been this hot.
1000 years? Are you sure about that? It seems to me that there has only been records kept for maybe 130 years. Not to mention the fact that some records are of surafce water temp. and others are of air temp.
I don’t doubt that all the crap we humans spew into the atmosphere isn’t doing anybody any good, but nobody can claim that the temperature is directly affected by ‘global warming’. The truth is we don’t know if this is a part of a typical interstital period.
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### Author:  [@Yossarian](https://boards.straightdope.com/u/Yossarian)
#### Post date: [January 3, 2000, 2:55pm UTC](https://boards.straightdope.com/t/global-warming-and-a-rise-in-water-levels-from-arctic-ice-melts/5747/16 "2000-01-03T14:55:00Z")
It’s never been this hot?
Actually, this is _almost_ as cold as it has ever gotten. Almost all of our geologic past has seen climates significantly more tropical than the Holocene’s. During the Mesozoic (peaking in the Cretaceous), sea level was so high that most of the central United States and Canada were covered and there is no evidence for Mesozoic glaciation of any kind (continental or mountain). Our present cooling trend began in the late Eocene-early Oligocene (between roughly 40 and 30 Ma), probably as a result of widespread volumnous volcanism during these epochs (actually, why the cool-down started is, of course, much-debated; as a volcanologist, this is the idea _I_ like). This cooling trend peaked in the Pleistocene (1.8 Ma to 10,000 bp) with the “Ice Ages”. Between each of the ice ages (continental glaciation episodes) was an “interglacial” that lasted on the order of 10,000 to 100,000 years before the next ice age. The last ice age ended 10,000 bp (and is the definition for the start of the Holocene). So, one argument that could be made is: Of course it’s getting warmer! That’s what happens during an interglacial! It’s not unlikely that another ice age is a few decades (ice core records have shown that the climate can _naturally_ change in a matter of decades) to a few thousand years; in fact, in the mid- to late-70’s the common environmentalist “chicken little” cause wasn’t global warming–it was global cooling.
Bottom line: it’s nowhere near as hot as it has ever gotten. Maybe it is hotter than it has been over the past century, but a century isn’t even within analytical precision of isotopic dating when compared with the geologic past. Are we polluting? Should we curb pollution? Yes both times! Is our pollution causing the climate to change? Compared to natural instigators of climate change, our contribution is probably close to negligible. But, you know, alarmist science attracts funding from alarmist politicians and bureaucrats.
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### Author:  [@UncleBeer](https://boards.straightdope.com/u/UncleBeer)
#### Post date: [January 3, 2000, 4:04pm UTC](https://boards.straightdope.com/t/global-warming-and-a-rise-in-water-levels-from-arctic-ice-melts/5747/17 "2000-01-03T16:04:00Z")
If anyone is interested, here’s a couple of articles from the current issue of _Scientific American_ that shed a bit of light on the Ice Age cycles of Earth.
[http://www.sciam.com/2000/0100issue/0100hoffman.html](http://www.sciam.com/2000/0100issue/0100hoffman.html)
[http://www.sciam.com/2000/0100issue/0100infocus.html](http://www.sciam.com/2000/0100issue/0100infocus.html)
The story in the first link even claims
> [@](#):
>
> For the past million years, the earth has been in its coldest state since animals first appeared…
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Easy one-step assembly instructions.
Pour **Beer A** in **Uncle B**.
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### Author:  [@Diceman](https://boards.straightdope.com/u/Diceman)
#### Post date: [January 3, 2000, 4:35pm UTC](https://boards.straightdope.com/t/global-warming-and-a-rise-in-water-levels-from-arctic-ice-melts/5747/18 "2000-01-03T16:35:00Z")
Actually, Threemae, alot of those Pacific atolls **do** just happen to be at the correct height. Any mariner will tell yow about underwater peaks and ridges that can wreck your boat if you’re not careful. These are landmasses just like islands. The difference is that they are not quite tall enough to break the surface and become islands. There are plenty of islands (most of volcanic origin) that stick way above the surface. There are also landmasses that are nowhere near tall enough to reach the surface, but noone maps these because they’re neither inhabitable nor a hazard to shipping. If the sea level rises, those flyspecks that are three feet above the surface will become underwater shoals or sandbars, and islands with more elevation will become a little smaller and shorter.
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“I had a feeling that in Hell there would be mushrooms.” -The Secret of Monkey Island
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### Author:  [@Diceman](https://boards.straightdope.com/u/Diceman)
#### Post date: [January 3, 2000, 4:58pm UTC](https://boards.straightdope.com/t/global-warming-and-a-rise-in-water-levels-from-arctic-ice-melts/5747/19 "2000-01-03T16:58:00Z")
Another thing: The question of whether the water level will rise or fall is quite complex. Ice is less dense than liquid water, so all of the ice that’s floating atop the ocean will cause the sea level to drop if it melts. The arctic pack ice and antarctic ice shelves are in this category. Ice that’s sitting on land will make the sea level rise if it melts, because that’s adding water that is not currently in the ocean. The ice atop Antarctica, as well as the ice in Canada, Alaska, Siberia, etc are in this category. Thus, the effect of the icecaps melting is a question of the net effect of two opposing processes. Finally (to increase the confusion), alot of scientists think that large parts of Antarctica and Greenland are actually below sea level if you strip away the ice. If true, much of this ice would go to “filling in” the area above the submerged land if it melts.
Lest you think this question’s a simple one… 🙂
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“I had a feeling that in Hell there would be mushrooms.” -The Secret of Monkey Island
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### Author:  [@RavingMad](https://boards.straightdope.com/u/RavingMad)
#### Post date: [January 4, 2000, 6:07am UTC](https://boards.straightdope.com/t/global-warming-and-a-rise-in-water-levels-from-arctic-ice-melts/5747/20 "2000-01-04T06:07:00Z")
I’ve been meaning to post a very similar question for some time, but kept putting it off. Now that I’m beaten to the punch, I’ll add what I can.
I think Diceman is dead on when he suggests the answer to rising ocean levels is none too easy. However, I think he glosses over a tiny point which makes the equation just that much more difficult. I agree when he says
> [@](#):
>
> Ice that’s sitting on land will make the sea level rise if it melts, because that’s adding water that is not currently in the ocean. – Diceman
.
But I have to quibble with this statement:
> [@](#):
>
> Ice is less dense than liquid water, so all of the ice that’s floating atop the ocean will cause the sea level to drop if it melts. – Diceman
That’s oversimplifying just a bit, I think. Since floating ice (in the form of an iceberg, for example) is likely both above and below the water level, its melting would create the “opposing processes” he refers to later. The ice above the water line (let’s say 20% of the iceberg’s mass) adds to the ocean level when it melts. But the remaining 80% of the iceberg’s mass below the water line will decrease the ocean level when it melts, as the water will take up less volume in its liquid phase than it does in its solid phase.
So what happens? On one hand, every drop of water that comes from the iceberg’s exposed 20% adds one drop to the water level, while every drop of water that comes from the iceberg’s submerged 80% decreases the water level – but only by a very tiny amount.
Diceman also suggests that the sea would fill in landmasses that had previously been covered by water. But perhaps the exposed land masses, now free from hundreds of millions of tons of ice, would actually spring up out of the ocean, resulting in decreased ocean levels once that mass is no longer submerged.
## Since it is such a complex question, I’ve often wondered if scientists take into account the “opposing processes” of melting ice when they suggest that world ocean levels would rise if the icecaps melt.
~ Complacency is far more dangerous than outrage ~
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