From the University of Haifa via Eurekalert
The sea level has been rising and falling over the last 2,500 years
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  IMAGE: Rising and falling sea levels over relatively short periods do not indicate long-term trends. An assessment of hundreds and thousands of years shows that what seems an irregular phenomenon today…
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“Rising and falling sea levels over relatively short periods do not indicate long-term trends. An assessment of hundreds and thousands of years shows that what seems an irregular phenomenon today is in fact nothing new,” explains Dr. Dorit Sivan, who supervised the research.*
The sea level in Israel has been rising and falling over the past 2,500 years, with a one-meter difference between the highest and lowest levels, most of the time below the present-day level. This has been shown in a new study supervised by Dr. Dorit Sivan, Head of the Department of Maritime Civilizations at the University of Haifa. “Rises and falls in sea level over relatively short periods do not testify to a long-term trend. It is early yet to conclude from the short-term increases in sea level that this is a set course that will not take a change in direction,” explains Dr. Sivan.
The rising sea level is one of the phenomena that have most influence on humankind: the rising sea not only floods the littoral regions but also causes underground water salinization, flooded effluents, accelerated coastal destruction, and other damage.
According to Dr. Sivan, the changing sea level can be attributed to three main causes: the global cause – the volume of water in the ocean, which mirrors the mass of ice sheets and is related to global warming or cooling; the regional cause – vertical movement of the earth’s surface, which is usually related to the pressure placed on the surface by the ice; and the local cause – vertical tectonic activity. Seeing as Israel is not close to former ice caps and the tectonic activity along the Mediterranean coast is negligible over these periods, it can be concluded that drastic changes in Israel’s sea levels are mainly related to changes in the volume of water.
In the present study, in light of earlier studies, research student Ayelet Toker and Dr. Sivan, set out to examine Israel’s sea level over the past 2,500 years, based on data deduced from many coastal archaeological findings. They made a careful selection of findings that have been reliably and accurately dated, and first focused on findings that were excavated by the Antiquities Authority in Acre of the Crusader period. These revealed that the sea level during the Crusader period – just 800 years ago – was some 50-90 centimeters lower than the present sea level. Findings from the same period at Caesarea and Atlit reinforced this conclusion. When additional sites were examined from periods before and after the Crusader period, it was revealed that there have been significant fluctuations in sea level: During the Hellenistic period, the sea level was about 1.6 meters lower than its present level; during the Roman era the level was almost similar to today’s; the level began to drop again during the ancient Muslim period, and continued dropping to reach the same level as it was during the Crusader period; but within about 500 years it rose again, and reached some 25 centimeters lower than today’s level at the beginning of the 18th century.
“Over the past century, we have witnessed the sea level in Israel fluctuating with almost 19 centimeters between the highest and lowest levels. Over the past 50 years Israel’s mean sea level rise is 5.5 centimeters, but there have also been periods when it rose by 10 centimeters over 10 years. That said, even acute ups and downs over short periods do not testify to long-term trends. An observation of the sea levels over hundreds and thousands of years shows that what seems a phenomenon today is as a matter of fact “nothing new under the sun”, Dr. Sivan concludes.
Here’s another idea: when there is more ice mass above sea level at the poles, this causes the polar axis to compress, and bulging the planet further outward at the equator. This lowers sea levels and forces more water to the poles, which increases the polar compression, further bulging the equator. This process can cause far more significant changes in sea levels nearer to the equator than is justified merely by changes in ocean volume.
mikelorrey please read at least:
Clark, J.A., Farrell, W.E., Peltier, W.R., 1978. Global changes in
postglacial sea level: a numerical calculation. Quaternary Research
9, 265–287.
Funny how sometimes you can discover things from the past that actually debunked the IPCC reports…
Take a look at that section (you have to scroll down) about The `Isle of the Dead’ in Tasmania, from the late John L. Daly…
http://news.bbc.co.uk/2/hi/science/nature/467007.stm
It is also very possible that the sea level is going down over there.
http://news.bbc.co.uk/2/hi/science/nature/467007.stm
http://www.john-daly.com/herald.gif
“… Seeing as Israel is not close to former ice caps and the tectonic activity along the Mediterranean coast is negligible over these periods, it can be concluded that drastic changes in Israel’s sea levels are mainly related to changes in the volume of water. …”
That statment is utter, unambiguous poppycock. The Jordan Valley is an active rift zone where Israel is being separated tectonically from western Asia. It is essentially an extension of the Red Sea Valley and the great rift zones of eastern Africa. The Mediterranean itself is over supplied with faults and volcanoes and the history of seismicity is one of the most intense on the planet.
Tectonism, in addition to faulting, causes buckling and long, very slow moving “waves” of structural movement that can raise and lower land surfaces over millenial, century-long and even decadal time spans. The USGS monitors “bulges” because of the potential that energy stored in such structures might release abruptly through faulting rather dissipate in plastic deformation. NO place with a notable history of seismicity can be considered to have “negligible” tectonic activity. Further, the word “negligible” begs questions as to what “significant” would mean in the same context. A single earthquake within the historic period elevated portions of the Sierra Nevada over 10 feet.
Antonio San (10:16:31) : edit
mikelorrey please read at least:
Clark, J.A., Farrell, W.E., Peltier, W.R., 1978. Global changes in
postglacial sea level: a numerical calculation. Quaternary Research
9, 265–287.
Yes, read it. It should also be noted that since oceanic water breached Gibraltar, the Bosporous, and the Red Sea thousands of years ago, the mass of the inundation water will have cause significant loading upon the Earth’s mantle locally, raising sea levels over time as the mantle is depressed locally with viscous mantle mass forced into neighboring areas.
I am but a simple car mechanic but I know that Istanbul stands on at least 3 intersecting fault lines (I used to get Nat Geographic at one time) and have seen photos of the sunken modern buildings on the coast of Turkey (water level half way up the window frames of the ground floor. How can anyone determine what effect all the plate movement has on global sea levels? it seems to me to be vastly more complicated than the, so far unreachable, holy grail of accurate weather prediction! even if CO2 was a problem (and I am sure it aint) taxing the west into 3rd world poverty is the dumbest way of coping with the wholly unpredictable changes.
Since many have brought up the topic of the Netherlands (my country of birth):
The Dutch know better than anyone else how to protect from flooding. Heck, if New Orleans had hired Dutch engineers some years before Katrina, then Katrina would have never happened with respect to the massive flooding and damage.
I’ve been there, I’ve seen it. Any place in the world that is *sincerely* in danger from rising sea levels just needs to hire a bunch of Dutch engineers.
” Stacey (03:02:27) :
Sea Levels at Harlech Castle in North Wales construction completed Circa 1290″
Interesting, because if the tide level of England has “receded” considerably since 1290 leaving their dock high and dry, it’s the opposite of Israel where “the sea level during the Crusader period – just 800 years ago – was some 50-90 centimeters lower than the present sea level.”
@Phil A (05:48:16) :
‘Sea Levels at Harlech Castle In North Wales:
Probably that there has been a lot of coastal sedimentation since 1290. It’s not so much that the sea level has lowered as that the coastline has moved outward.’
Quite. In Welsh, an area where estuarial/riverine sedimentation or dune has in effect moved the coastline out is termed a morfa (f sounds as a v in Welsh). The area below and beyond the castle seaward is called Morfa Harlech.
“Morfa Harlech is one of two extensive sand dune systems which make up much of the soft Meirionnydd coastline, extending from the Mawddach estuary in the south to Black Rock Sands in the north west. … In fairly recent times the sea lapped at the base of the cliff on which Harlech Castle stands, but the accumulation of sand and the development of the dunes gradually pushed the shoreline westward.
Today, Morfa Harlech is considered one of the most important actively growing dune systems in Britain and is highly protected, forming part of the Morfa Harlech and Morfa Dyffryn SAC, Morfa Harlech SSSI and the Pen Llŷn a’r Sarnau SAC.’
http://www.ccw.gov.uk/landscape–wildlife/protecting-our-landscape/special-landscapes–sites/protected-landscapes/national-nature-reserves/morfa-harlech.aspx