# Has "global warming" ever submerged any islands in the past? **URL:** \ **Category:** Factual Questions\ **Created:** [August 4, 2003, 3:21am UTC](https://boards.straightdope.com/t/has-global-warming-ever-submerged-any-islands-in-the-past/192825 "2003-08-04T03:21:56Z")\ **Posts on this page:** 12\ **Page:** 1
**Author:** ![BrainGlutton](https://avatars.discourse-cdn.com/v4/letter/b/82dd89/32.png) [@BrainGlutton](https://boards.straightdope.com/u/BrainGlutton)\ **Post date:** [August 4, 2003, 3:21am UTC](https://boards.straightdope.com/t/has-global-warming-ever-submerged-any-islands-in-the-past/192825/1 "2003-08-04T03:21:56Z")
This might belong in GD, but as it is a question with a scientific/historical/factual answer, I’m starting it in GQ. Moderators, please feel free to move it if you think it’s appropriate. Environmentalists, discussing the dangers of “global warming,” sometimes assert that it would cause enough of the polar icecaps to melt to significantly raise the sea level worldwide, which would not only flood coastal cities, but cause some islands to entirely disappear beneath the waves. Especially some of the very small islands of the Pacific. (I have never heard anyone seriously argue that this process would inundate the whole world, as in Kevin Costner’s _Waterworld._) But “global warming” has happened before, hasn’t it? I mean, within the global cycle of major ice ages and warm periods, there is a less extreme cycle of warming and cooling, and it works fast enough to be perceptible within recorded human history. In the Middle Ages, Greenland was warm enough that the south part, at least, was suitable for farming. Then the earth became cooler, and the Norse colony of Greenland died out. In Shakespeare’s time, the world was in a cool period, a “little ice age,” and the Thames usually froze over in winter. What I’m wondering is, have any of these warming cycles caused the sea level to rise enough to inundate whole islands? Is there any record of this happening? ---
**Author:** ![Askance](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/askance/32/8281_2.png) [@Askance](https://boards.straightdope.com/u/Askance)\ **Post date:** [August 4, 2003, 3:35am UTC](https://boards.straightdope.com/t/has-global-warming-ever-submerged-any-islands-in-the-past/192825/2 "2003-08-04T03:35:01Z")
It raised it enough to inundate vallleys, which became the Mediterranean and Black Seas, for instance. Most of the islands that are so close to sea level that this could have happened say between 1000 and 500 years ago, are coral islands in the Pacific so there wouldn’t be any written record. According to [http://www.cnn.com/1999/ASIANOW/australasia/12/29/kiribati.millenium/](http://www.cnn.com/1999/ASIANOW/australasia/12/29/kiribati.millenium/) it is already happening: “Sections of the islands are inundated during high tide, erosion has caused houses to collapse and some regions have been evacuated”. ---
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [August 4, 2003, 3:42am UTC](https://boards.straightdope.com/t/has-global-warming-ever-submerged-any-islands-in-the-past/192825/3 "2003-08-04T03:42:36Z")
[There was an island in front of the “Pillars of Hercules”](http://news.bbc.co.uk/2/hi/science/nature/1554594.stm) It sank beneath the waves as the ice age ended and sea level rose 11,000 years ago. ---
**Author:** ![Kiwi\_Fruit](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kiwi_fruit/32/12_2.png) [@Kiwi\_Fruit](https://boards.straightdope.com/u/Kiwi_Fruit)\ **Post date:** [August 4, 2003, 4:11am UTC](https://boards.straightdope.com/t/has-global-warming-ever-submerged-any-islands-in-the-past/192825/4 "2003-08-04T04:11:27Z")
> [@](#): > > \*Originally posted by BrainGlutton \* > \*\*Environmentalists, discussing the dangers of “global warming,” sometimes assert that it would cause enough of the polar icecaps to melt to significantly raise the sea level worldwide, which would not only flood coastal cities, but cause some islands to entirely disappear beneath the waves. \*\* I haven’t a cite for islands being inundated, but I’d comment that it’s not polar ice caps melting that cause the initial rise, but expansion of the existing water as it warms up. As for land areas being covered or exposed as water levels change, over a longer time period, look at atlases that show land masses as they were during pre-historic times, i.e. 250,000 years ago or several million years ago. Cheers, KF ---
**Author:** ![Opus1](https://avatars.discourse-cdn.com/v4/letter/o/858c86/32.png) [@Opus1](https://boards.straightdope.com/u/Opus1)\ **Post date:** [August 4, 2003, 4:47am UTC](https://boards.straightdope.com/t/has-global-warming-ever-submerged-any-islands-in-the-past/192825/5 "2003-08-04T04:47:36Z")
What about the Bering land bridge that allowed the first settlers to cross into the Americas? It’s now submerged. Weren’t there also connections between the various islands of South Asia that allowed humans to walk there? ---
**Author:** ![Gairloch](https://avatars.discourse-cdn.com/v4/letter/g/d2c977/32.png) [@Gairloch](https://boards.straightdope.com/u/Gairloch)\ **Post date:** [August 4, 2003, 5:19am UTC](https://boards.straightdope.com/t/has-global-warming-ever-submerged-any-islands-in-the-past/192825/6 "2003-08-04T05:19:51Z")
“Banaba (Ocean Island) in Kiribati is one of the three great phosphate rock islands in the Pacific Ocean,” it says. And a coral atoll is by definition the subsidence of a volcanic island. So, has anyone made a (relatively) fixed point measurement and determined whether the sea is rising towards Banaba, or whether Banaba is doing the only thing it can do, geologically, which is to sink? I’m not sure what the question of a ‘record’ of this kind of thing refers to – evidence that it has happened in the past or a smoking gun in recent times to use as damning evidence – but in terms of geological time there are sea fossils to be found at the top of the Rocky Mountains, since once upon a geological epoch or three ago they were thrust up out of what was then nothing but sea to slimy sea. All manner of theories abound, but the planet seems not to be all that malleable, even though we think we can make any difference one way or the other, and takes its own sweet time deciding what to do next. Islands have disappeared, islands have been formed, and much as I’d like to be that arrogant I’m pretty sure that men had nothing at all to say about it. Gairloch ---
**Author:** ![AskNott](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/asknott/32/5790_2.png) [@AskNott](https://boards.straightdope.com/u/AskNott)\ **Post date:** [August 4, 2003, 5:28am UTC](https://boards.straightdope.com/t/has-global-warming-ever-submerged-any-islands-in-the-past/192825/7 "2003-08-04T05:28:16Z")
The city of Venice, Italy is sinking. I don’t know if it’s due to global warming, or to the weight of Italian seriousness ---
**Author:** ![Erroneous](https://avatars.discourse-cdn.com/v4/letter/e/71c47a/32.png) [@Erroneous](https://boards.straightdope.com/u/Erroneous)\ **Post date:** [August 4, 2003, 12:58pm UTC](https://boards.straightdope.com/t/has-global-warming-ever-submerged-any-islands-in-the-past/192825/8 "2003-08-04T12:58:56Z")
I think BrainGlutton is asking whether any islands have been inundated _since_ the last great rise in sea level caused by the end of the last glacial period. I’m not 100% sure, but I think any changes in sea level brought about by the little ice age, or other ‘minor warmings’, would have been tiny, on the order of centimetres at most, and so would have been insignificant in comparison to the tides. On the other hand, the vertical movement of the tectonic plates may have caused land to either become submerged, or emerge from the ocean, within the last 8000 years or so. I vaguely remember reading about how parts of England that were by the sea in the middle ages are currently considerably inland, due to that whole section of plate rising slowly. This process is independant of global warming, of course, but it could have had the same effect. ---
**Author:** ![BrainGlutton](https://avatars.discourse-cdn.com/v4/letter/b/82dd89/32.png) [@BrainGlutton](https://boards.straightdope.com/u/BrainGlutton)\ **Post date:** [August 4, 2003, 8:16pm UTC](https://boards.straightdope.com/t/has-global-warming-ever-submerged-any-islands-in-the-past/192825/9 "2003-08-04T20:16:35Z")
Posted by **AskNott:** > [@](#): > > The city of Venice, Italy is sinking. I don’t know if it’s due to global warming, or to the weight of Italian seriousness Perhaps it’s because the city was built on a swamp and its buildings are supported by thousands of stone pilings which are, after many centuries, finally starting to sink into the mud? Of course, I originally proposed this topic to cast light on the question of whether any islands really are in danger of being submerged by global warming in the **future.** My thinking was, how could that happen, if it’s never happened before? But **has** it happened before? Posted by **Kiwi Fruit:** > [@](#): > > I haven’t a cite for islands being inundated, but I’d comment that it’s not polar ice caps melting that cause the initial rise, but expansion of the existing water as it warms up. That’s news to me! Got a cite for that? I always hear the problem discussed in terms of the icecaps; and I never hear anybody mention how much water there is in the icecaps, or whether that amount, melted, really would be enough to raise the sea level. ---
**Author:** ![CookingWithGas](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cookingwithgas/32/485_2.png) [@CookingWithGas](https://boards.straightdope.com/u/CookingWithGas)\ **Post date:** [August 4, 2003, 8:58pm UTC](https://boards.straightdope.com/t/has-global-warming-ever-submerged-any-islands-in-the-past/192825/10 "2003-08-04T20:58:55Z")
[Tuvolo](http://old.smh.com.au/news/0107/24/opinion/opinion6.html) is expected to be submerged but I do not know authoritatively if it is due to global warming. ---
**Author:** ![Agback](https://avatars.discourse-cdn.com/v4/letter/a/977dab/32.png) [@Agback](https://boards.straightdope.com/u/Agback)\ **Post date:** [August 4, 2003, 9:15pm UTC](https://boards.straightdope.com/t/has-global-warming-ever-submerged-any-islands-in-the-past/192825/11 "2003-08-04T21:15:34Z")
> [@](#): > > \*Originally posted by AskNott \* > \*\*The city of Venice, Italy is sinking. I don’t know if it’s due to global warming, or to the weight of Italian seriousness \*\* According to an item of p20 of the August 2 2003 issue of _New Scientist_, the level of the Adriatic Sea is rising four millimetres per year owing to global warming. At the same time, the tectonic plate on which Venice rides is sinking at about 1 millimetre per year as it is subducted under another plate. There is no mention of how rapidly the pilings on which Venetian buildings stand are sinking into the sediment on which the city is built, but I guess that that figure would vary from building to building. Regards, Agback ---
**Author:** ![BrainGlutton](https://avatars.discourse-cdn.com/v4/letter/b/82dd89/32.png) [@BrainGlutton](https://boards.straightdope.com/u/BrainGlutton)\ **Post date:** [August 6, 2003, 8:23pm UTC](https://boards.straightdope.com/t/has-global-warming-ever-submerged-any-islands-in-the-past/192825/12 "2003-08-06T20:23:28Z")
Just came across an article on the Tech Central Station website ([http://www.techcentralstation.com/1051/envirowrapper.jsp?PID=1051-450&CID=1051-080503F](http://www.techcentralstation.com/1051/envirowrapper.jsp?PID=1051-450&CID=1051-080503F)), about a dispute between two schools of “paleoclimatoligists.” Harvard astrophysicist Willie Soon believes the global warming now being observed is part of a natural climatic cycle. There was the “Medieval Warm Period” (MWP)from roughly 800 to 1300 A.D., and then there was the Little Ice Age (LIA) from 1300 to 1900, and now we’re again entering a warm period: > [@](#): > > Soon and colleagues published “Reconstructing Climatic and Environmental Changes of the Past 1000 Years: A Reappraisal” back in March in the British journal Energy and Environment. Soon et. al. reviewed about 250 paleoclimate studies and made some interesting conclusions. They found that the Medieval Warm Period and Little Ice Age were both real and global, albeit with significant regional variations. The authors concluded that "the Medieval Warm Period of 800 to 1300 A.D. and the Little Ice Age of 1300 to 1900 A.D. were worldwide phenomena not limited to the European and North American continents. _While 20th century temperatures are much higher than in the Little Ice Age period, many parts of the world show the medieval warmth to be greater than that of the 20th centuries."_ (Emphasis added.) In other words, the warming of the 20th century is not unprecedented. There have been earlier periods of warming, taking place long before the industrial revolution and the large emissions of human-induced greenhouse gases into the atmosphere. University of Virginia climate statistician Michael Mann and his colleagues not only deny the present global warming is a natural phenomenon, they deny the MWP or the LIA ever took place: > [@](#): > > Advocates of the man-made warming theory, such as Mann and his colleagues, are climate change skeptics – that is, they believe the historical record says climate has been relatively stable compared to today, and that the 20th century warming is anomalous, due to human influence, and deeply troubling. Their argument is that the local periods of warming and cooling, while large, were not synchronous, so they do not represent true “climate change.” In the last ten years they have developed a number of statistical techniques to support their claims. > > Mann’s 1998 paper was the high point in this scientific movement. Mann claimed to find no vestige of the either the Little Ice Age or the Medieval Warm Period in the paleoclimate record. His sample of that record was very small, just 10 locations. Despite that shortcoming, the Mann et. al. study was central to the 2001 Third Assessment Report of the United Nations Intergovernmental Panel on Climate Change (IPCC), when the IPCC concluded that most of the late 20th century warming was probably due to human influence. There is no overstating how influential the Mann et. al. paper has been within climate change science circles – and in the public debate beyond.