Scientists uncover a dramatic rise in sea level and its broad ramifications

Feb 09, 2009

Scientists have found proof in Bermuda that the planet's sea level was once more than 21 meters (70 feet) higher about 400,000 years ago than it is now. Their findings were published in the journal Quaternary Science Reviews Wednesday, Feb. 4.

Storrs Olson, research zoologist at the Smithsonian's National Museum of Natural History, and geologist Paul Hearty of the Bald Head Island Conservancy discovered sedimentary and fossil evidence in the walls of a limestone quarry in Bermuda that documents a rise in sea level during an interglacial period of the Middle Pleistocene in excess of 21 meters above its current level. Hearty and colleagues had published preliminary evidence of such a sea-level rise nearly a decade ago, which was met with skepticism among geologists. This marine fossil evidence now provides unequivocal evidence of the timing and extent of this event.

The nature of the sediments and fossil accumulation found by Olson and Hearty was not compatible with the deposits left by a tsunami but rather with the gradual, yet relatively rapid, increase in the volume of the planet's ocean caused by melting ice sheets.

A rise in sea level to such a height would have ramifications well beyond geology and climate modeling. For the organisms of coastal areas, and particularly for low islands and archipelagos, such a rise would have been catastrophic. The Florida peninsula, for example, would have been reduced to a relatively small archipelago along the higher parts of its central ridge.

"We have only to look at Bermuda to begin to assess the impact for terrestrial organisms or seabirds dependant on dry land for nesting sites," said Olson. "This group of islands in the Atlantic was so compromised as a nesting site for seabirds that at least one species of shearwater became extinct as well as the short-tailed albatross, marking the end of all resident albatrosses in the North Atlantic."

Determining the timing and extent of this global rise in sea level is not only important for interpreting the influence that it may have had on biogeographical patterns and extinctions of organisms on islands and low-lying continental coastal areas, it is also critical for anticipating the possible effects of future climate change. This particular interglacial period is considered by some scientists to be a suitable comparison to our current interglacial period. With future carbon dioxide levels possibly rising higher than any time in the past million years, it is important to consider the potential effects on polar ice sheets.

Biogeographers, conservationists and many others in the biological sciences must take these findings into consideration, Olson urged. "These findings are incredibly important and have major relevance because of their potential predictive value since this sea-level rise took place during the interglacial period most similar to the present one now in progress. So it is essential that the full extent and duration of this event be more widely recognized and acknowledged."

Source: Smithsonian

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User comments : 9

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4.4 / 5 (5) Feb 09, 2009
Thirty-five years ago, I was attending school in Florida where the marine and space science students discussed the 70 foot height of a no Ice Cap sea level. All of the Ice has to melt, about 4,500 years at the quickest (about 40 feet at that point), then the depressed ground under Ice sheets around the world has to rebound to get sea level up by 70 feet, after about 35,000 years.

Congratulations on finding the new evidence. The tsunami theory never did stand up to the light of day.
jonnyboy
3 / 5 (10) Feb 09, 2009
This is obviously proof that man has had previous civilizations that have risen to the heights or our current attempt, else how could we have had enough GW to melt the ice to raise the ocean to flood the land to create the debris to turn into fossils to provide the proof that the article sites.
SDMike
3.8 / 5 (6) Feb 09, 2009
Have these researchers never been to Florida? The state is covered with evidence of the rise and fall of our oceans.
Nartoon
2.6 / 5 (5) Feb 10, 2009
"a rise in sea level during an interglacial period of the Middle Pleistocene in excess of 21 meters above its current level"

So we can have much higher sea levels with higher CO2, but just not AGW CO2 because there was no man made CO2 then!
MikeB
3 / 5 (4) Feb 10, 2009
This is proof positive that Al Gore is right! Don't wait 35,000 years to sell your beachfront property... procrastination is a bad thing. Also get rid of all your modern conveniences and start living like the Amish (you might even want to grow a beard)...
Do it for the children...
Fighting bad CO2 for you,
Mike
GrayMouser
3 / 5 (4) Feb 10, 2009
This is proof positive that Al Gore is right! Don't wait 35,000 years to sell your beachfront property... procrastination is a bad thing. Also get rid of all your modern conveniences and start living like the Amish (you might even want to grow a beard)...
Do it for the children...
Fighting bad CO2 for you,
Mike

Is this going to end up with "good CO2" and "bad CO2" just like the supposed isomers of cholesterol (which don't exist)?
mikiwud
1 / 5 (1) Feb 15, 2009
There was a complete program on tele dedicated to this. The land is rising giving fosilised beaches as the sea level rises and falls. The oldest are at the top, the reverse to normal fosilised layers. The dateing would be easy, but the relationship of sea level to land rise would be open to different interpretations. Was the previous beach formed at a low sea level, how much had the land level varied etc?
lengould100
1 / 5 (1) Mar 03, 2009
Where the heck are you guys above getting "35,000 years"? Any references, or is that just more of the denier's science quality (lack of)? As far as the scientific record shows, no interglacial on record has ever lasted more than about 11,000 years, then its back into the ice age.
jeffsaunders
not rated yet Apr 16, 2009
The last time we had higher sea levels recorded was 120,000 years ago and indications in this article suggest it took 50 years to rise 3 meters.

http://www.physor...292.html

The last glacial period is the best-known part of the current ice age.




Perhaps we are just entering an interglacial period and if so we can expect sea levels to rise by anything up to 20 meters or thereabouts.

And all this could happen without the help of one single person.

This also indicates that there much of mans history has been conducted when the planet was a lot cooler than it is now. And given that the sea level may currently be anything up to 10 meters deeper than it has been, we may find that most of the cities of the world built more than 10,000 years ago could easily be well below sea level today.

The same thing that could happen to us has happened already when the world warmed up to the current level.