Skip to comments.Ancient Rome's fish pens confirm sea-level fears
Posted on 08/16/2004 5:06:16 AM PDT by ckilmer
Ancient Rome's fish pens confirm sea-level fears
09:30 16 August 04
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Coastal fish pens built by the Romans have unexpectedly provided the most accurate record so far of changes in sea level over the past 2000 years. It appears that nearly all the rise in sea level since Roman times has happened in the past 100 years, and is most likely the result of human activity.
Sea-level change is a measure of the relative movement between land and sea surfaces. Tide-gauge records show that the sea level has been rising 1 to 2 millimetres a year since widespread measurements began around 1900, but do not pinpoint when the trend started.
Earlier sea levels can be estimated from geological data, but the accuracy is limited to about half a metre, which is not enough to precisely chart the history of sea-level rise.
So Kurt Lambeck of the Australian National University in Canberra turned to fish pens on the Tyrrhenian coast of Italy for a more accurate record of ancient sea level.
Ice age rebound
The Romans dug these fish pens into bedrock, and the water line in these well-preserved structures shows that the sea level along the Italian coast 2000 years ago was 1.35 metres below today's levels. "They were used for only a very short time, so they make rather nice markers," says Lambeck.
He then analysed how land elevations changed along the Italian coast due to both plate tectonics and the after-effects of the last ice age. In a paper to appear in the journal Earth and Planetary Science Letters, he concludes that geological processes pushed the land up by 1.22 metres over last two millennia, which means that the global sea level rose by 13 centimetres.
That is only about 100 years' worth of rise at the present rate of around 1 to 2 millimetres per year, implying that nearly all of it has occurred since 1900. While there is no proof that human activity is to blame, "I can't think of a natural process that would have started in 1900," he says.
The result "is a significant one", says Jonathan Gregory, who studies global changes in sea level at the University of Reading, UK. The finding supports the idea, based on the few tide-gauge records that extend back two centuries, that the rise in sea level did indeed accelerate about a century ago.
While Gregory cautions that this does not prove that global warming is responsible, both he and Lambeck agree that the results fit the rise in ocean volume expected from global warming melting glaciers in the industrial age.
It sounds as if you'll have plenty of time to move your house if you're too close to the ocean.
How does this socialist dingbat know that the sea level has risen? Maybe the land sunk.
"I can't think of a natural process that would have started in 1900"
Ergo, SUV's are bad, m'kay?
I'm not too sure what scientific conclusions may be drawn from a single data point. Staying in the Mediterranean area, I recall the plain between the site of Troy and the beach where the Greeks landed is a mile or more wider then in ancient times. Further the area around Alexandria that held the palace of Cleopatra is totally submerged now, and has been for centuries. The Mediterranean seems to have been active for a long longer then just 100 years.
Has anyone noticed the Tidal Basin in DC rearing up to swallow the national monuments in the last century ?
I am always struck by their glib pronouncements that rising sea levels have to be cause by humans.
Did humans cause the "little Ice Age"?
It should be no secret that the earth warms and cools for a variety of reasons and, as is being discovered,that warming or cooling can be sudden. Why do they assume that it has to be gradual and measured?
There are many things in Nature that are not.
The moon is falling and we're all gonna die!!
This is speculation on top of speculation on top of wishful thinking on top of political agendas. Just a cursory glance at this article reveals far too many unknown and unknowable variables for any even tentative conclusions.
Something is fishy about this guys science. ;-)
Earth warms and fish pens...suddenly, I feel like taking Monday off and go wet a line.
Note the photo of the mean sea level mark made in 1841 by Sir James Ross (look for a horizontal line). Note the sea level at low tide. The total range of tide is one meter in this part of the world, and this mark is very close to what would be the middle of this one meter range.
BTW, any one been to Venice lately? Seen the water lapping at the steps of the city? As is well known, Venice is subsiding and the same thing probably happened to the old Roman fish farms, as an earlier poster noted. Of course, this fact has been so well known for such a long time that it could not be hijacked by the enviro-brownshirts.
The global warming enthusiasts and their fellow travelers live in a fact-free fantasy land. Whatever 'facts' they have about this or other issues, they make up.
My math skills are sometimes off but...
if the water level is 1.35 meters higher now than 2000 years ago and the land mass in that area has risen 1.22 meters in the same period wouldn't the change be 2.57 meters and not 13 centimeters?
This story sounds bogus to me...
I'm with ya! Hearing the siren call of the wild troutsie myself....
BTW, the official reason I'm taking the day off is to celebrate Nicki Hilton's early morning marriage to the Masked Marvel.