From Oregon State University:
Ancient tides different from today – some dramatically higher
CORVALLIS, Ore. – The ebb and flow of the ocean tides, generally thought to be one of the most predictable forces on Earth, are actually quite variable over long time periods, in ways that have not been adequately accounted for in most evaluations of prehistoric sea level changes.
Due to phenomena such as ice ages, plate tectonics, land uplift, erosion and sedimentation, tides have changed dramatically over thousands of years and may change again in the future, a new study concludes.
Some tides on the East Coast of the United States, for instance, may at times in the past have been enormously higher than they are today – a difference between low and high tide of 10-20 feet, instead of the current 3-6 foot range.
And tides in the Bay of Fundy, which today are among the most extreme in the world and have a range up to 55 feet, didn’t amount to much at all about 5,000 years ago. But around that same time, tides on the southern U.S. Atlantic coast, from North Carolina to Florida, were about 75 percent higher.
The findings were just published in the Journal of Geophysical Research. The work was done with computer simulations at a high resolution, and supported by the National Science Foundation and other agencies.
“Scientists study past sea levels for a range of things, to learn about climate changes, geology, marine biology,” said David Hill, an associate professor in the School of Civil and Construction Engineering at Oregon State University. “In most of this research it was assumed that prehistoric tidal patterns were about the same as they are today. But they weren’t, and we need to do a better job of accounting for this.”
One of the most interesting findings of the study, Hill said, was that around 9,000 years ago, as the Earth was emerging from its most recent ice age, there was a huge amplification in tides of the western Atlantic Ocean. The tidal ranges were up to three times more extreme than those that exist today, and water would have surged up and down on the East Coast.
One of the major variables in ancient tides, of course, was sea level changes that were caused by previous ice ages. When massive amounts of ice piled miles thick in the Northern Hemisphere 15,000 to 20,000 years ago, for instance, sea levels were more than 300 feet lower.
But it’s not that simple, Hill said.
“Part of what we found was that there are certain places on Earth where tidal energy gets dissipated at a disproportionately high rate, real hot spots of tidal action,” Hill said. “One of these today is Hudson Bay, and it’s helping to reduce tidal energies all over the rest of the Atlantic Ocean. But during the last ice age Hudson Bay was closed down and buried in ice, and that caused more extreme tides elsewhere.”
Many other factors can also affect tides, the researchers said, and understanding these factors and their tidal impacts is essential to gaining a better understanding of past sea levels and ocean dynamics.
Some of this variability was suspected from previous analyses, Hill said, but the current work is far more resolved than previous studies. The research was done by scientists from OSU, the University of Leeds, University of Pennsylvania, University of Toronto, and Tulane University.
“Understanding the past will help us better predict tidal changes in the future,” he said. “And there will be changes, even with modest sea level changes like one meter. In shallow waters like the Chesapeake Bay, that could cause significant shifts in tides, currents, salinity and even temperature.”
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I guess the moon was closer back then as well!
Hudson’s Bay is a tide buffer! Who knew?
Not surprising at all. It has been long known that the Bay Of Fundy’s tidal range has changed dramatically over the last 4000 years, as evidenced by drowned forest snags found on its shores. A large contrast to the eight-plus cubic kilometers of water that surges through Minas Channel twice a day, which also moves an immense amount of sediment, which in turn changes the geomorphology of the bay incrementally…
The BOF is at the head of the Gulf of Maine which acts as a huge confining ‘scoop’, directing the tides inland. A tiny change in sea level/tidal range in the Gulf of Maine would be amplified by the Bay of Fundy’s funnel shape. Oh No! /sarc
Pete H says:
August 2, 2011 at 8:52 am
I guess the moon was closer back then as well!
Yep, actually it was 😉 Though, I guess I might just be failing to adequately detect your humour….
Old news. Of course the propaganda being peddled by CAGW religious zealots portrays that tides are affected by man and ONLY man.
“One of these today is Hudson Bay, and it’s helping to reduce tidal energies all over the rest of the Atlantic Ocean. But during the last ice age Hudson Bay was closed down and buried in ice, and that caused more extreme tides elsewhere.” [David Hill]
This is fascinating. Any related links will be appreciated.
When Hudson Bay was “closed down” and buried in ice the Ocean would have been lower so the higher tidal action on the East Coast would have been at lower elevation (or out farther from the current coast line). Back farther in time geomorphic features such as Trail Ridge along the eastern edge of the Okefenokee, now quite far inland, were wave and tide additions to the landscape.
Thanks for this one. Good stuff.
I think the tide has gone out on global warming…
Re: Pete H
Yes, it was. Roughly, about 38mm for every year.
The earth also spun faster. As the moon moves away the earth’s spin slows down by about 15 microseconds per year.
“Part of what we found was that there are certain places on Earth where tidal energy gets dissipated at a disproportionately high rate, real hot spots of tidal action,” Hill said. “One of these today is Hudson Bay”
I always thought Hudson’s Bay looked like a Helmholtz resonator, but never thought it would be functional! This is fascinating.
20 feet is what we get here on the East Coast of England, more elsewhere of course. Many creeks and small harbours are only accessible for 1.5 to 2 hours either side of high tide. The CAGW crowd cry doom all the time of course, I shall be launching my dinghy from the upstairs windows if they are anything like correct.
During the Devonian the moon was quite a bit closer–enough to make tidal action a considerably more potent geological force in coastal behavior. Tidal pools where common, and fish with gills were stranded on a twice-daily basis. The ability to survive these strandings, in combination with higher SST’s than now, led to the evolution of lungs. In Devonian times the majority of fish–especially shallow water fish–had lungs.
With the evolution of reptiles fish with lungs went extinct in the oceans, but the swim bladder of the Teleosts almost certainly evolved from a lung. The coelacanths survived by taking to deep water, where the lung atrophied. Otherwise, the sea surface fish with lungs were replaced by reptiles, dinosaurs, birds and mammals, and the lungfish survived only in tropical rivers. Annual lungfish estivation probably began as a twice-daily and later fortnightly stranding, and advanced to monthly and longer periods of burrowing.
We sentient sojourners may owe our existence to the moon and the tides. –AGF
what we think we know …
xxx
what we don’t know …
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These guys might be dead on of course. But my immediate reaction is that this simulation probably makes Global Climate Modeling look like high precision tooling by comparison.
All I really know about tides is that they are much more complex than most of us think. I’ll be interested to see if anyone who actually knows about tides has comments
The tides, they are a changin!
Posted on August 2, 2011 by Anthony Watts
“From Oregon State University:
Ancient tides different from today – some dramatically higher
CORVALLIS, Ore. – The ebb and flow of the ocean tides, generally thought to be one of the most predictable forces on Earth, are actually quite variable over long time periods, in ways that have not been adequately accounted for in most evaluations of prehistoric sea level changes.
Due to phenomena such as ice ages, plate tectonics, land uplift, erosion and sedimentation, tides have changed dramatically over thousands of years and may change again in the future, a new study concludes. One of the most interesting findings of the study, Hill said, was that around 9,000 years ago, as the Earth was emerging from its most recent ice age, there was a huge amplification in tides of the western Atlantic Ocean. The tidal ranges were up to three times more extreme than those that exist today, and water would have surged up and down on the East Coast.
One of the major variables in ancient tides, of course, was sea level changes that were caused by previous ice ages. When massive amounts of ice piled miles thick in the Northern Hemisphere 15,000 to 20,000 years ago, for instance, sea levels were more than 300 feet lower. But it’s not that simple, Hill said. Many other factors can also affect tides, the researchers said, and understanding these factors and their tidal impacts is essential to gaining a better understanding of past sea levels and ocean dynamics. “Understanding the past will help us better predict tidal changes in the future,” he said. “
Maybe again the solar dynamics can help understanding the past.
I see two major mechanisms in this object. First, as Prof. Ehrlich *) has proposed saw tooth oscillations from resonant diffusion wave modes which correlate with the well known temperature proxies from Vostock Antarctica over millions of years, and second there is an evidence that this resonance process is superimposed by a solar tide process, that is in harmony with the celestial bodies.
*) Robert Ehrlich, ‘Solar Resonant Diffusion Waves as Driver of Terrestrial Climate Change’,
I have done a paper one year ago:
SOLAR SYSTEM GEOMETRIES AND TERRESTRIAL CLIMATE
http://volker-doormann.org/ghi_solar_s.pdf
In that paper I have argued on both suggestions and have shown, that in general the temperature anomalies over a wide time range can be simulated.
Prof. G. Patzelt has shown from old trees bottom out of melting gletcher in altitudes were are no trees anymore today that the temperatures in the Alps were higher 7000 y BP and are still decreasing until today.
http://volker-doormann.org/images/ghi4n_aletsch_retreat0.jpg
This graph is made by Prof. G. Patzelt and is taken from his slide talk in Berlin:
http://www.iuf-berlin.org/wm_files/wm_pdf/prof._patzelt_berlin_4.12.2009.pdf
Over the simple density/temperature relation of water for normal pressure it should be possible to simulate the after last ice age pattern also for the future.
Volker
I live within 100 metres of an old fishing harbour. Built 150 years ago. Highest high tides hit 7.4 metres. It looks like the harbour could cope with a 1 metre rise – just! So current quoted sea level rises are a bit ho-hum. Sadly I will need around 15 metres of sea level rise to turn my property into true sea front category. 🙂
Re; Nigel S August 2, 2011 at 9:43 am
As Nigel says, the tides get a lot higher elsewhere than the East coast of the UK.
In the Britstol Channel (between Bristol SW England and Wales) the extreme range is just over 15 m (average over 8 m, frequently in excess of 10 m). This makes it only second in the world to the dead heat between Bay of Fundy and Ungava Bay in NE Canada.
http://www.pol.ac.uk/home/insight/tidefaq.html#10
I used to have an office where I could look over a jetty at Portishead, next to Avonmouth: this gave a measure of the range.Since then they have built a tidal lock:
http://www.worldseafishing.com/index.php?news=3027
http://www.tuesdaynightclub.co.uk/Tour_94/94SevernEst.html
A G Foster…
Estivation? cool. After looking it up I’ve decided I’d like to “estivate” for the duration of the CAGW madness….
Ancient and hugely chaotic system in large variability shocker
The result of this paper means that the historical sea level reconstructions are now obsolete as well if they haven’t taken this effect into account.
There has been several recent articles posted here on sea level reconstructions and I don’t think this impact was mentioned.
@Jeff Carlson:
Hey Jeff, what about the line representing what we don’t know we don’t know, that line of x’s probably would go to the moon!
Yeah it doesn’t take much.
The (pretty large) bay of Mont Saint Michel in North France was an oak forest within historical memory. It is theorized ( not sure if it’s been proven) that an ancient dune/ blockage at the sea mouth was washed away in the very late roman era where powerful storms and tides hit the north of France.
The early medieval sea flooding in Northern Germany/ Holland/Southern Denmark was of similar nature, but more temporary ( though still washing away miles of shore), massive storms + high tides reaching miles inland and killing lots of people.
Still confused how Hudson’s bay, effectively a large salt water lake, can affect tides in the Atlantic.
Eh?
In Cape Cod, Massachusetts (Wellfleet) today, the low to high tide spread was 13.3 ft.
Simon says:
August 2, 2011 at 11:08 am
Ancient and hugely chaotic system in large variability shocker
Nope, Actually there’s nothing wrong with my Humour detection abilities……. found some…….
It’s the Sun wot dun it!
Our climate ‘scientist’ enemies have always refused to believe that the Sun has ANY influence on Earth’s climate – not so! Now one of our friends at DMI proves otherwise, and he even estimates how much.
Here is a preview: “Solar activity–climate relations: A different approach”
http://www.sciencedirect.com/science/article/pii/S1364682611001866
There’ll be plenty of opportunity for us to rub the AGW believers noses in it when we discuss it down on the village green after the Master posts a notice on the Church noticeboard
Well, DUH!