Do super-tides kick start interglacials ?

Guest essay by Clive Best

It is proposed that for the last 800,000 years  super-tides caused by maxima in orbital eccentricity have been the key factor needed to break up large northern ice sheets to enable the 41,000 year insolation cycle to initiate an interglacial. Insolation alone was sufficient to melt back the ice sheets over the previous 4.4 million years, as observed by the long series of 41,000 year glaciation cycles in the LR04 Do18 stack[1]. The obliquity cycle was broken once an underlying cooling trend had increased glacial ice sheet extent beyond a threshold for “Milankowitch” summer melting.

Since that time huge tidal forces amplified by increased eccentricity,  have been required to bring a glacial cycle to an end by carving and shelving the ice sheets. Once initiated a rapid deglaciation proceeds due to enhanced insolation with positive albedo feedback, resulting in a sawtooth shape. The most exceptional tides occur when the perihelion of the sun and the moon coincide and both orbits are at maximum eccentricity. This process can explain both the origin of the 100,000y cycle of ice ages and  the transition from  earlier 41,000y glaciation cycles which have so far remained a mystery[2].

clip_image002

Fig 1a. 5 million years of benthic foram dO16 data. The blue curve is a fit to Milankovitch harmonic data described inPhenomenology of Ice Ages.

clip_image004

Fig 1b. Correlation of inter-glacials with maximum eccentricity of Earth’s orbit

clip_image006

Fig 1c. Correlation of larger obliquity and warmer temperatures. A calculation of the insolation at the poles that demonstrating the dominance of the 41,000 year cycle is shown in Fig 2.

clip_image008

Fig 2. Maximum and total solar insolation calculated at the poles during last 600,000 years. The total annual insolation and the N-S asymmetry show the underlying effect of the 41,000 obliquity signal.

The basic hypothesis behind this proposal is the following.

  1. 5 million years ago a gradual cooling of the climate began (Fig 1a). This was most likely due to plate tectonics. First Antarctica moved further south to sit over the South Pole isolating the Southern Ocean. Second the Panama isthmus closed cutting off circulation between the Atlantic and Pacific.
  2. A regular glacial cycle began driven by the 41,000 year change in obliquity of  the earth’s axis. Higher obliquity brings higher insolation to both poles modulated by the precession of equinoxes. The 41,000y signal dominates glaciation cycles from 5 million years ago until 1 million years ago. Meanwhile the intensity of glacial periods was slowly increasing as  global cooling due to plate tectonics continued.
  3. 900,000 years ago this general cooling reached a critical stage because the  increase in spread of ice sheets in the Northern hemisphere became too large to fully melt back during the next peak in obliquity. The cycle of 41,000y ice ages was broken.
  4. Something else was now needed to trigger ice ages and that something was extreme tidal forces caused by maximum orbital eccentricity. When these coincided with peak insolation in the Arctic Circle the breakup of the northern ice sheets could begin and they collapsed rapidly within one precession cycle.

To understand  these tidal forces we need to understand what perigee spring tides are. These are exceptional tides that occur when the new moon coincides with the lunar perigee (closest distance of approach to the earth). These tides are typically 20% larger than normal, because tides are tractional forces that depend  on 1/R^3. Perigean tides occurs every 411.78 days (spring tide at lunar perigee). However there are a series of even rarer and more extreme perigean tides:

§ Perigean Eclipse Tides (PET) which occur every 2.99847 years which is when a Perigean spring tide coincides with the Earth-Sun-Moon all aligned in the ecplitic plane. The lunar and solar tides then pull directly together on the earth rather than through  a cosine(declination) offset.

§ Finally there are Super Perigean Eclipse Tides(SPET) which occurs every 1832 years. This super tide occurs when a Perigean Eclipse Tide coincides with the  earth also at perigee in its orbit around the sun so that the solar tide is also at its maximum value possible. These rare events cause tidal forces some 30% above normal. There is also a 5000 year modulation in the strength of SPET.[3]

Now consider what additional effects variations in the “Milankovitch” cycle of eccentricity would have on these Perigean tides.

The minimum distance of approach at perigee depends on the orbital eccentricity both for the moon and the earth. Tides are a tractional force whose greatest  effect is felt near the poles. During both the Arctic and Antarctic winters with zero insolation there are clear signals of tidal effects on temperature (4). Furthermore tides have also a direct effect on sea ice. Postlethwaite et al.[5] write

Tidal mixing within the water column and at the base of the sea ice cover can increase the heat flow from deeper water masses towards the surface causing decreased freezing and increased melting of sea ice and possibly the formation of sensible heat polynyas (Morales-Maqueda et al., 2004; Willmott et al., 2007; Lenn et al., 2010). The tidal currents can additionally increase the stress and strain on the sea ice and cause leads to open periodically within the sea ice cover (Kowalik and Proshutinsky, 1994).

Tidal forces therefore  act to break up ice sheets and change ocean heat flows. Fortnightly changes of 20% in ice stream flow have also  been observed in Antarctica due to spring tides. [6]

The  100,000 and 400,000 year cycles  in the ellipticity of the Earth’s orbit are caused by regular gravitational effects of the other planets as they orbit the sun,  particularly those of Jupiter and Saturn. Every 100,000 years the orbits of Jupiter and Saturn align themselves so that their net gravity perturbs the Earth’s orbit causing it to elongate and become more elliptical. This cycle reaches a maximum every 400,000 years in  regular fashion. The gravitational force of the sun on the moon is more than twice that of the Earth. For an observer  in outer space the moon appears to orbit the sun just like any other planet. Its orbit is perturbed by the Earth’s gravity making it slightly concave.  It is only from Earth that it appears to us to be in an elliptical orbit around the Earth. The moon’s orbit is therefore also affected by the gravitational pull of the other planets inducing a similar (Milankovitch) variation of eccentricity in its orbit around the sun. However this also causes an increased elliptical orbit of the moon around the earth because they have different mass.

How large can the tides get during 100,000y cycles of maximum eccentricity? Figures 4 and 5 show calculations of the change in tidal forces due to the sun and the moon for various values of orbital eccentricity. These calculations are based on the distance to the earth for different times in the year for the sun, and in the sidereal month for the moon. Tides are tractional forces which depend on 1/R^3 which explains why the moon has a larger tidal pull on the oceans than does the much more massive sun. At spring tides the two tidal forces are superimposed:

clip_image010

Fig 4: Relative strength of the solar lunar tidal force – proportional to 1/R^3

The largest solar tides are up to 20% higher than those we experience today. I have been unable to find any information about Milankovitch calculations of effects of the lunar orbit but I will assume a proportional increase to that of the earth. Given that assumption we can look at the more important lunar tide.

clip_image012

Fig 5: Variation in strength of lunar tides with orbital eccentricity relative to today.

We see that spring lunar tides for a lunar orbit twice the current eccentricity would be about 60% higher than they are today. Lunar tides are about twice the strength of solar tides so overall spring tides would have been at least 50% stronger than they are today, and Super Perigean tides would have been 20% stronger again.

Are  these  super-tides the catalyst to break up the large northern ice sheets and exit ice ages once every 100,000 years ?

==============================================================

References

1. Lisiecki, L. E., and M. E. Raymo (2005), A Pliocene-Pleistocene stack of 57 globally distributed benthic d18O records, Paleoceanography, 20, PA1003

2. Maureen Raymo & Peter Huybers, Unlocking the mysteries of the ice ages, Nature Vol 451/17 P. 284, 2008

3. The 1,800-year oceanic tidal cycle: A possible cause of rapid climate change, Charles D. Keeling and Timothy P. Whorf, PNAS (2000) 3814-3819

4. The influence of the lunar nodal cycle on Arctic climate, Harald Yndestad, ICES Journal of Marine Science, 63(3) 401, 2005

5. The effect of tides on dense water formation in Arctic shelf seas, C. F. Postlethwaite, M. A. Morales Maqueda, V. le Fouest,*, G. R. Tattersall1,**, J. Holt, and A. J. Willmott, Ocean Sci., 7, 203–217, 2011

6. Fortnightly variations in the flow velocity of Rutford Ice Stream, West Antarctica, G.H. Gudmundsson, Nature 444, 1063-1064, 2006

7. On the factors behind large Labrador Sea tides during the last glacial cycle and the potential implications for Heinrich events, Brian K. Arbic,1 Jerry X. Mitrovica,2 Douglas R. MacAyeal,3 and Glenn A. Milne, PALEOCEANOGRAPHY, VOL. 23, PA3211

Advertisements

  Subscribe  
newest oldest most voted
Notify of
Jean Parisot

We can measure this hypothesis in how many years?

Rob

Keeling’s paper is outstanding. And makes a lot more sense to me. If correct, we are on the verge of another big Cold Spell lasting decades.

apachewhoknows

Chaco Canyon New Mexico.
Three rounded rocks with circles.
The old ones following the sun and moon cycles.
These old ones lived out in the open, they slept out in the moon light.
They knew some things, possible more than Michael Mann and his tribe.

apachewhoknows

Necessity the mother of invention.

Greg Cavanagh

I thought interglacials were caused by continential drift.
But it’s good to have alternate theories too.

I look forward to the Day when all theories are thrown out the window and we collectively say to ourselves. “Oh.. So that is what causes Humanities extinction.” By Ice or by Fire it matters not.

Alan Robertson

Cooper says:
January 14, 2014 at 3:49 pm
_____________________________
Go away.

wayne Job

That the large changes to Earths climate are cyclical like clock work, one can only conclude that the answers lay in the cosmos.
The coinciding alignments of our solar system and our place in the galaxy seem overwhelmingly to be the cause. The mechanism or mechanisms that cause the swings are open to conjecture.
Astrology this is not, but some basic premises of astrology coupled to astronomy may explain why the ancients were so enamored by the concept.
Notwithstanding that the mechanism is not known, this knowledge can give us some predictive skills. Fathoming the mechanism may take some time, as it is not just climate science that has succumbed to consensus.

Tim

Some very interesting points made in this paper.
Along the same lines its interesting to note that over the period of 1991-2011 there were 7 ‘supermoon events’ where the moon orbits closer to the earth than is usual, when usually there is only 3 such events in any 20 year period. It so happens that in this time period we have also witnessed the thinning of the Northern Ice Cap, so this paper would explain that behaviour much better than the missing heat scenario.
I think its highly likely that these variations in the orbits of our planetary system is the main factor in all global, and most local geological and atmospheric events.

Alan Robertson says:
January 14, 2014 at 3:59 pm
Why? I’ve been following this issue for the better part of a decade, The staggering amount of information we don’t know, yet pretend we do to a remarkable tenth’s of a degree spanning 100’s of thousands of years. Getting tiring. Like to get it over with sooner or later..

Eric Barnes

Great post Clive! Thanks!

bit chilly

this certainly seems to be on the right track.it has always puzzled me why there was not more investigation into the HUGE effects caused by the masses of the oceans movement variation depending not only on tidal range,but the changing areas where the greatest gravitational pull is.
this is most likely the main cause of shifting ocean currents,and of their variation in strength in recent times. it would be interesting to see a plot of the various oceanic oscillations over the same timescale if that is possible.

timetochooseagain

The key to understanding the glaciation cycle is to understand that, while orbital variations don’t cause large changes in the “global average TOA radiative forcing” they cause significant shifts in the seasonal and latitudinal *distribution* of solar insolation. It is likely that this (and things like changing geography) act on the climate system by their effects on dynamics, the atmospheric circulation, and in turn, clouds. This allows such factors to give rise to changes in the mean climate state, without a need to appeal to global radiative forcings like CO2, and without the sensitivity to such being high. This, moreover, is why such changes have typically involved tropical climates not much different than the present, but polar climates *dramatically* different. Changes in the meridional heat transport as induced by such heterogeneous forcing-this would naturally arise, given the above, when combined with a strong negative feedback in the tropics. In that regard it is worth noting that, at least according to CLIMAP, there were even parts of the tropical Pacific ocean that were actually *warmer* than the present during the Last Glacial Maximum.
Of course, changes in ocean circulation could cause a similar effect, and would probably be related.

1sky1

The idea that ocean tides break up large floating ice-sheets runs afoul of considerations of spatial scale. There is scarcely enough difference in tidal elevation over the typical dimensions of such ice-sheets (tens of kilometers) to exert the forces necessary to fracture them. Only in the case of ice-sheets fastened to shore is such a mechanism plausible.

old construction worker

Sounds good, but…..
“…..that something was extreme tidal forces caused by……” Or maybe an asteroid hit an ocean. Or maybe an mile high avalanche of ice and rock cause a tsunami. Just not enough information yet.

Jimbo

 

Do super-tides kick start interglacials ? 

Which reminds me whether global warming kick starts ice sheets growth?
 

Letter To Nature – (16 January 1992); doi:10.1038/355244a0
Will greenhouse warming lead to Northern Hemisphere ice-sheet growth?
Gifford H. Miller* & Anne de Vernal†
* Center for Geochronological Research, INSTAAR, University of Colorado, Boulder, Colorado
ALTHOUGH model simulations predict a higher mean global temperature by the middle of the next century in response to increased atmospheric concentrations of greenhouse gases1, the response of the cryosphere to specific changes in latitudinal and seasonal temperature distribution is poorly constrained by modelling2,3 or through instrumental measurements of recent variations in snow cover4and ice thickness5,6. Here we examine the recent geological record (130 kyr to present) to obtain an independent assessment of ice-sheet response to climate change. The age and distribution of glacial sediments, coupled with marine and terrestrial proxy records of climate, support arguments that initial ice-sheet growth at the beginning of the last glacial cycle occurred at high northern latitudes (65–80° N) under climate conditions rather similar to present. In particular, the conditions most favourable for glacier inception are warm high-latitude oceans, low terrestrial summer temperature and elevated winter temperature. We find that the geological data support the idea that greenhouse warming, which is expected to be most pronounced in the Arctic and in the winter months, coupled with decreasing summer insolation7 may lead to more snow deposition than melting at high northern latitudes8 and thus to ice-sheet growth.
 

Jimbo

See my last comment. The game plan of Warmists is to have a paper ready for any eventuality so they can point to it as backing their crazy ideas. Whether the IPCC agrees or not is (at that point in time) irrelevant. Same for the endless model runs.This is a scam and people must try and see through it.

lee

Just one point
‘to an end by carving and shelving the ice sheets’ = calving?

I agree with Old Construction worker. What is heartening is that despite the consensus, real science still is happening. And perhaps we will overcome the handicap of the meme.

David

>> The most exceptional tides occur when the perihelion of the sun and the moon coincide and both orbits are at maximum eccentricity.
…the perihelion of the sun and moon? …both orbits?
If I didn’t already know what you were talking about, I would have no idea what you were talking about with that sentence.

EWF

I would quantify the insolation caused by orbital eccentricity. That it does increase insolation is seen with a simple thought experiment: imagine the greatest eccentricity such that the Earth grazes the Sun once a year, with apehelion of twice the average orbital radius — we would all vaporize at perihelion. This is because insolation goes as the inverse square of the Earth-Sun distance, so perihelion is hotter than the apehelion is cool. So quantify this to see how much of the 41,000-yr temperature variation is accounted for. Already done, I suppose, but not seen in this article.

Arno Arrak

I quote Tim January 14, 2014 at 4:01 pm:
“…. over the period of 1991-2011 there were 7 ‘supermoon events’ where the moon orbits closer to the earth than is usual, when usually there is only 3 such events in any 20 year period. It so happens that in this time period we have also witnessed the thinning of the Northern Ice Cap, so this paper would explain that behaviour much better than the missing heat scenario…”
This is just another example where fanciful explanations of Arctic warming abound, all for lack of knowledge that I provided a full explanation in 2011. Arctic warming started at the turn of the twentieth century, after two thousand years of slow, linear cooling. It halted for thirty years in mid-century, then resumed, and is apparently still active. I say apparently because this year’s ice cap was twice the size of last year’s icecap. Remembering the previous mid-century halt in warming, we must keep in mind that what has happened in nature before can happen again. When the warming first started there was no increase of atmospheric carbon dioxide and this rules out the greenhouse effect as its possible cause. The only logical cause left is a rearrangement of North Atlantic currents at the turn of the century that started to carry warm Gulf Stream water into the Arctic Ocean. The warming pause in mid-century would then correspond to a temporary return of the previous flow pattern. You can download my paper from Climate etc. web site.

I suspect the major effect of the tides on climate is to alter the mixing rate of the oceans, bringing more (or less) warm water to the polar surface, as well as to alter the circulation between northern and southern hemisphere.
Any change in the mixing rate is significant, due to the overwhelming amount of thermal energy stored in the oceans as compared to the atmosphere.
The larger tides may not lead to increased ice breakup except in shallow water, or in areas where there are large tidal streams.

Gifford H. Miller* & Anne de Vernal†
* Center for Geochronological Research, INSTAAR, University of Colorado, Boulder, Colorado
Here we examine the recent geological record (130 kyr to present) to obtain an independent assessment of ice-sheet response to climate change. The age and distribution of glacial sediments, coupled with marine and terrestrial proxy records of climate, support arguments that initial ice-sheet growth at the beginning of the last glacial cycle occurred at high northern latitudes (65–80° N) under climate conditions rather similar to present.
===================
so, 130kyr ago there were cavemen driving around in SUV’s. Or were conditions similar simply due to natural variability? In which case our current climate is completely explainable without any human causes required, and our most likely future is glaciation.

The problem with the insolation theory of glaciation is that an eccentric orbit does not significantly change the total amount of energy the earth receives from the sun. Thus the 100kyr problem in climate science. Radiative changes are insufficient to explain the peak in glaciation at 100kyrs.
However, this problem goes away if one considers that tidal forces also peak on a 100kyr cycle, and the importance of the oceans in determining climate. Celestial mechanics still cause the ice ages, but the mechanism is tidal forces as well as isolation.
Thousands of years ago humans used the position of the stars in the heavens to predict the coming of the seasons, long before they understood the cause. Our brains are no larger than theirs.

Let us not forget the annual solar apparent declinational tides, and the 27.32 day period lunar declinational tides, that drive most of the global meridional circulation patterns.
http://research.aerology.com/aerology-analog-weather-forecasting-method/

I started to post the below comment on a thread at the Telegraph. I deleted and didn’t post but I had copied it because this had been on my mind for the last several weeks. Upon reading this post here on WUWT, I believe that there is a fit with this article. Note that this started as a reply to another comment….
“It is helpful to take a look at least once a week to stay in tune with changes. I watch daily. The western Arctic experienced a warm pulse through the Bering Strait right at the end of November. The rapid sea ice growth lessened and at this point in time, Arctic sea ice is right on the edge of -2 standard deviations. Quite a turn around. It has dropped below the 2012/13 trend line. At the same time though, Antarctic sea ice moved beyond +2 standard deviations almost 4 weeks ago and remains that way with the possibility of continued acceleration of this trend. What I find fascinating is that the Arctic sea ice growth stopped it,s rapid growth at the same time and within a week had dropped to the -2 sd, where it still sits. Last summer, while discussing the upcoming Arctic minimum sea ice extent, I noticed something regarding shifts in sea ice growth. There is some form of interaction with certain phases of the moon and polar sea ice growth. I first noticed it while watching the Antarctic trend line last year, but now I see the Arctic shows a similar relationship, even though in the Arctic it has led to diminishing growth, while in Antarctica the effect is accelerating growth. I am looking at NSIDC to view the trend lines. If you look at the last 3 months of the Arctic trend line, you will notice that right after the dark of the moon of 11/3, 12/3 and 1/1 there is a noticeable deceleration in sea ice growth. If you look at the Antarctic index, you will see that after an ascending half moon, 11/10, 12/9, and now 1/9 there has been an acceleration in the trend line. You can see similar in last years rise to the Antarctica maximum.”
There is some more thought to this that I will add in another comment.

Berényi Péter

One wonders what effect these supertides would have on MOC (Meridional Overturning Circulation), which is not driven by thermal processes, but by pure mechanical energy input like tides and winds. To see this it is enough to mention the usual thermohaline explanation is flawed, because dense cold water of high salinity can descend only until the abyss gets saturated, then it stops. Therefore we need another, independent process that supplies buoyancy to the deep. Heat conductivity of seawater is far too small to do that and diffusivity of salts is even smaller by two orders of magnitude, while with no additional input mixing is prohibited by the stable layered structure of oceans.
The job is done by internal waves breaking over rugged bottom features at mid ocean ridges and at continental margins of complex geometry, inducing deep turbulent mixing at specific sites. Internal waves themselves are excited by tides and wind driven surface waves, mostly over the Southern ocean. If tidal excitation is increased, the MOC is suspected to get more vigorous, so it would transport more warm saline surface water to the Northern Atlantic to be cooled and sunk there, because it has more room to go to down below. In this process it would warm up the region, which can contribute to the collapse of the surrounding great mid latitude continental ice sheets.

Place an ice cube in a glass of water. Stir gently back and forth with a spoon until the ice is melted. record the time. Repeat the experiment, but this time do not stir.
Which time did the ice melt fastest? Does this demonstrate that even without any change in insolation, the polar ice should melt sooner in the summer as the tides increase, reducing albedo, and leading to increased warming at the poles?

Owen in GA

Small comment on terminology: When speaking of generic orbits or orbits of multiple bodies, it is better to state it as periapsis or pericenter than perihelion or perigee (or pericynthion) as the root states what body is in the center (helion – sun, gee – earth, cynthion – moon). Of course most people would have to look the word up since it is so rarely used, so maybe a misuse is better communication.

I just read Tim,s comment above. That makes so much sense now. I first had noted this last year during all of the interest on the Nenana Ice Classic and the upcoming ‘predict the Arctic minimum’.
The Antarctic trend line clearly showed well spaced steps that made me think of a moon connection. I had a link for lunar positions and it showed that every acceleration was occuring right after an ascending 1/2 moon. Another thought in looking at it was that it was not a regular monthly event, but was intermittent. It does not show for every moon cycle, or there is another force dominant that overrides the effect. The above article filled in a thousand blanks with fresh thought.
I had alluded to this in a comment about 3 weeks during the recent icecapades in Antarctica. The reason being that the trend line is again showing the signal over the last 2 months and is currently showing the 3rd progression right now. The 3rd event started at the end of last week per my older comment. The Sea Ice Index is starting to show this next step which should decrease the melt rate and hold the trend line above last years 2012/13 trend line. Given how short the summer is down there, it would seem a good possibility for a strong base into the next regrowth. It could very well highlight the real importance of the Antarctic to the climate system.

Ian Wilson

Congratulations Clive for proposing this very interesting hypothesis.
However, this is not a new hypothesis as it is just taking an already established hypothesis and expanding it to longer time scales. I have been promoting a similar idea (on shorter time scales) for many years, with little or no response from anyone.
Starting in 2008, I have been promoting the idea that the variations in the Earth’s climate caused by the Sun appeared to be amplified in the World’s mean temperature for the simple reason that they are synchronized with variations in the effects of the Lunar tides upon the Earth’s climate. The logic train that I have consistently used goes as follows: :
1/ Motion Jovian planets –> variations in shape and tilt of lunar orbit –> long-term variations in in the influence of the lunar tides upon the Earth’s rotation, ocean and atmosphere —> long-term [inter-annual to decadal to centennial] variations in the Earth’s climate systems.
2/ Motion Jovian planets —> Sun’s Barycentric motion –> variations in rotation rate of the Sun via a spin-orbit coupling —> variations in the long-term level of solar activity –> variations in the effect on Earth’s climate systems.
********************
Here are some examples of my posts:
1. Are the Dansgaard-Oeschger (D-O) Warm Events driven by Lunar Tides?
http://astroclimateconnection.blogspot.com.au/2013/06/are-dansgaard-oeschger-d-o-warm-events.html
2. The synchronization between the Solar Inertial Motion and the Lunar Orbit
http://astroclimateconnection.blogspot.com.au/2010/03/synchronization-between-solar-inertial.html
3. Are Changes in the Earth’s Rotation Rate Externally Driven and Do They Affect Climate?
Wilson, I.R.G., 2011, Are Changes in the Earth’s Rotation
Rate Externally Driven and Do They Affect Climate?
The General Science Journal, Dec 2011, 3811.
Part of Abstract:
“We know that the strongest planetary tidal forces acting on the lunar orbit come from the planets Venus, Mars and Jupiter. In addition, we known that, over the last 4.6 billion years, the Moon has slowly receded from the Earth. During the course of this lunar recession, there have been times when the orbital periods of Venus, Mars and Jupiter have been in resonance(s) with the precession rate for the line-of-nodes the lunar orbit. When these resonances have occurred, they would have greatly amplified the effects of the planetary tidal forces upon the lunar orbit. Hence, the observed synchronization between the precession rate of the line-of-nodes of the lunar orbit and the orbital periods of Venus, Earth, Mars and Jupiter, could simply be a cumulative fossil record left behind by these historical resonances.”

Ian Wilson

Clive,
*****************
If you are just concerned with the absolute strength of lunar tides on the Earth’s surface, then the 18.03 year Saros cycle and its sub-multiples (i.e 3.0, 6.0, and 9.0 years) are your basic repetition cycle.
This is because 223 synodic months = 242 draconic months = 239 anomalistic months. In other words, if a New Moon occurs at perigee near one of the nodes of the lunar orbit [the conditions for a Solar Eclipse], another New Moon will occur at perigee near one of the lunar nodes 18.03 years later.
Another way to look at these absolute tidal pattern is in terms of the Perigean eclipse cycle which is determined by the synodic product between the 8.8501 (sidereal) year pro-grade precession of the lunar line-of-apse and the 18.60 (sidereal) year retro-grade precession of the lunar-line-of nodes:
(1/8.851 + 1/18.60)^(-1) = 5.997 (sidereal) years ~ 6.00 (sidereal) years
The perigean eclipse cycle also influences tidal events on the millennial time scale because the
return time for near coincidence of events of this cycle with perihelion is approximately 1,800 year.
These are the tidal cycles that Keeling & Whorf propose that effect the World’s mean temperature.
******************
My proposal is that it is more important to determine when the peak lunar tides synchronize with the seasons, In essence, I am claiming that the Earth’s climate is most influenced by the time it takes for the extreme Perigean spring-tides to re-synchronize with the Earth’s seasons. On time scales of few thousand years, this is equivalent to determining when the extreme Perigean spring tides re-aligns with Perihelion.
[Note: Of course on longer time scales, you would need to account for changes in the ellipticity of the Earth’s orbit, the obliquity of the Earth and the Precession of the Earth’s axis].
For those that want to learn more about the Perigean spring-tides:
http://astroclimateconnection.blogspot.com.au/2011/11/el-ninos-and-extreme-proxigean-spring.html
The repetition periods associated with the alignment of the Perigean spring-tides with Perihelion (i.e. the seasons) are 20.293, 10.147, 3.796, 1.898, 4.00, 15.00 and 19.00 years.
The 20.293 and 10.147 year periods come from the re-alignment of the synodic and anomalistic months
The 3.796 and 1.898 year periods come from the re-alignment of the synodic and draconic months
The 4.00, 15.00 and 19.00 year periods come from the re-alignment of the synodic and tropical year.
[Interestingly, if you look at all the beat periods of these periods that are shorter than 7 years, you find that they almost perfectly match the observed peak frequencies observed in the periodogram of the SOI index between 1950 and 1997 (Sidorenkov 2000)].
On longer time scales it is better to compare how long it takes for the perigee of the lunar orbit to point at the Sun at (or near) the time of Perihelion. This is 177 years and 1832 years.
However, when the Perigee of the Lunar Orbit is pointing at the Sun at (or very near to) Perihelion it does not necessarily mean that the phase of the Moon is either New or Full (Syzygy). hence, we need to ask the question: How do the phases of the Moon re-synchronize with the 177.0 year Perigee-Perihelion Cycle?
New or Full Moons that re-occur when the Perigee of the lunar orbit is pointing ta the Sun at (or near) the time of Perihelion are whole multiples of 739 years (i.e. 0.0, 739.0, 1478.0 and 2217.0 years).
Now, careful study of the New and Full Moons near 739.0 years shows that the strongest alignment between the phases of the Moon and the 177.0 year Perigee-Perihelion cycle occurs at Full Moon at 739.001 years. This contrasts with the starting phase which is a New Moon at 0.000 years.
Hence, it actually takes 1478.00 years (= 2 x 739.00 years) to complete the cycle where a New Moon occurs when Perigee points at the Sun at (or near) Perihelion once again.
This makes the long term realignment period for the Perigean spring tides with the seasons = 1478 years, which is very close to the 1470 year periodicity of the DO warming events.

Ian Wilson
pochas

Clive, thanks for your excellent work. I believe you have made an important contribution.

JudyW

The earth changes it’s orbit orientation relative to the galactic plane as it goes through the processional cycle. As far as I know, this would be true of all the planets. Most depictions show the orbit leaning to the left and cutting through the galactic plane at a 60° angle. 12,500 yrs from now, it would be shown leaning to the right at a 120°(?) angle.
As the solar plane moves directly in or away of the galactic wind (not solar wind), the climate changes. This only accounts for 1/4 of the 100,000 yr. glacial cycle so other aspects of the Milankovitch cycle may explain.
Saturn and Jupiter align about every 18-20 yrs.

Txomin

The topic is always interesting to me. Thank you for taking the time to share.

Best theory I’ve seen so far. Most of the others theories [see Wikipedia] come across as little more than hand-waving.

norah4you

Topic is interesting. Yes. But before the first point has been correctly looked into, then the question is nothing more than an assumption of the past. There are good geologic evidence for what happened when Pangea and other states of tectonical plates history occured. But linking that and super tidal waves the way the question does, isn’t valid argumentations.
Mind you. If you do a proper study on today’s Africa’s Horn, you will be able to see how at least 40 different nature phenomena interacting on tectonical plates.

Ian Wilson

I have placed an important associated blog post at:
http://astroclimateconnection.blogspot.com.au/2014/01/do-events-cause-rapid-warming-events-in.html
This post clears up some the confusion caused by the discrepancies between scaling chronologies of the GISP2, GRIP and NGRIP ice cores. As can be seen from the second graph in this blog post [that used the NGRIP-based Greenland Ice Core Chronology 2005 (GICC05) time scale] there is excellent agreement between the timing of the DO events and the rapid rise in polar temperatures.

John West

”Something else was now needed to trigger ice ages and that something was extreme tidal forces caused by maximum orbital eccentricity. When these coincided with peak insolation in the Arctic Circle the breakup of the northern ice sheets could begin and they collapsed rapidly within one precession cycle.”
”Are these super-tides the catalyst to break up the large northern ice sheets and exit ice ages once every 100,000 years ?”
Use of the terms glacial and interglacial would avoid the impression that “ice ages” (which is what the Earth has been in the whole time of glacial and interglacial cycles) are both triggered and exited by the same mechanism; like:

Something else was now needed to trigger interglacials and that something was extreme tidal forces caused by maximum orbital eccentricity. When these coincided with peak insolation in the Arctic Circle the breakup of the northern ice sheets could begin and they collapsed rapidly within one precession cycle.
Are these super-tides the catalyst to break up the large northern ice sheets and exit glacials once every 100,000 years?

An interesting idea overall; I’ll have to chew on it.

The problem with the insolation theory of glaciation is that an eccentric orbit does not significantly change the total amount of energy the earth receives from the sun. Thus the 100kyr problem in climate science. Radiative changes are insufficient to explain the peak in glaciation at 100kyrs.
I have never understood this fixation with averages. Today the difference in insolation between perihelion and Amphelion is about 60 w/m2. At Maximum eccentricity that number is as much as about 155 w/m2. Couple that with the variation caused with maximum and minimum obliquity (24.5 degrees down to 21.4 degrees), and you could pile up enough snow in the winter that it would not melt in the winter, starting a slow descent into an ice age. This started again about 4,000 years ago and is proceeding quite on time.

Steve R

It seems to me that continental glaciation needs a whole lot of snow, yet the arctic of today is just too dry. Is it possible that our thinking is backwards about the Arctic Ocean ice cover? Perhaps an ice free arctic, with circulation of warmer water of tropical origin (a portion of the Gulf Stream perhaps) is what is really required to transform the arctic literally into a snow factory.

Interesting. However, it remains to be explained why there is no signal in ice bubbles or benthic isotopes for the 400kyr cycle, which as you mention is the strongest and most stable of all the Milankovitch cycles.

phlogiston

Figure 1b shows the 400, 000 year modulation of the 100, 000 year eccentricity cycle. There is a huge variation in the peak amplitude such that the actual value of eccentricity at the peaks 800kya, 400kya and now are close to or even lower than the troughs of eccentricity at 600 kya and 200 kya.
However the remarkable thing is that all the eccentricity peaks of such widely differing amplitude seem to be equally effective in causing abrupt interglacials.
This means that the effect of eccentricity cannot be linear. It is acting as a periodic forcing of a nonlinear oscillator.
At the highest amplitude peaks of eccentricity 600 kya and 200 kya one can see a more ragged curve of glaciation with secondary smaller interglacials. This may support the idea of high eccentricity causing tidal disturbance of the ice sheets.

norah4you

Ian Wilson said:
January 14, 2014 at 8:53 pm
As can be seen from the second graph in this blog post [that used the NGRIP-based Greenland Ice Core Chronology 2005 (GICC05) time scale] there is excellent agreement between the timing of the DO events and the rapid rise in polar temperatures.
Fallacie of dignity shown in those lines – You and many other belive that an icecore can taken on land or in sea can show situation at the same actual spot/gps point for the last ten thousand years or more. That’s not true. First of all water in all forms tries to reach the lowest point. Secondly there is three different errosionfactors -needed to be fit into your analyse. wind- and temperatureerosion as well as erosion due to impacts from graviditation.
Why? Ice taken from one level hardly ever have the same density as ice taken from other levels. That we can thank basic Physic as well as the specific phenomena of Volcano eruptions for not to mention wind-directions and strength of long distributed less or more salt procentage in rain/snow falling down.
But that’s not all. Given that we are talking of Ice cores taken from Ice in North Pole where there aren’t any land under, a surface point never is located at the same spot/GPS-point over time. Please read About Nansen Fram Polar expedition. You will find that a ship frozen in Polar Ice as well as ice sheet itself moves and that surface ice you see around for example the ship Fram will follow Fram’s Ice drifting. Same goes for every surface spot from any period in time. That place goes around and moves around. It’s not possible to tell what the situation in point A was if you take an icecore and analyse it at point Z+X

Steve R says:
January 14, 2014 at 9:16 pm
It seems to me that continental glaciation needs a whole lot of snow, yet the arctic of today is just too dry. Is it possible that our thinking is backwards about the Arctic Ocean ice cover? Perhaps an ice free arctic, with circulation of warmer water of tropical origin (a portion of the Gulf Stream perhaps) is what is really required to transform the arctic literally into a snow factory.
———————————————————————————————————-
I had a thought similar to that about 4 years ago. I wondered if it was possible for the Arctic to mirror what happens with a lake effect snow off of the Great Lakes. If possible that could be a huge snow event. Imagine a storm that could drop 15 or 20 feet of snow within a day or two, and continue like that for multiple days. The biggest snowfalls that I witnessed were 12 ft in 3 days, and 6 ft in one day, 1970/71 at Lake Tahoe. It took several days to get the roads passable with that much snow.

dp

In the Seattle area we seem to have our most painful snowfall when the Pineapple Express rides in over the top of the Arctic Express and warm Pacific rain falls through a very cold Arctic air mass.
If this results in so little as a single snowflake falling, a dozen vehicles will spin out on it, three drivers will abandon their cars in the middle of it, 18 people will go to a Starbucks and wait it out, and no less than 10,000 people will tweet it. There will be sixty youtube videos of cars and buses slamming into each other on Queen Anne hill (a largely leftist burb of Jet City. BTW), and RealClimate will describe in slow stifling Algore speak that this is just further evidence of runaway, beyond the tipping point apoplectic anthropoheinous global climate refutation and that our sector of the galaxy is in grave danger from right wing gun thumping white American males as documented by the NYT and the Grauniad, both of whom are legendary centrist publications, just ask them.
At least that’s the way I remember it.

Ian Wilson

nora4you said:
“But that’s not all. Given that we are talking of Ice cores taken from Ice in North Pole where there aren’t any land under, a surface point never is located at the same spot/GPS-point over time.”
i know that you are trying to help nora4you. In addition, you have raised some good points which need to be considered when dealing with ice cores.
However, the GISP2, GRIP, NGRIP and Dye 2 ice cores were not taken at the North Pole but in the Greenland Ice-cap which is firmly wedged over the Greenland landmass. Hence, many of the concerns you have expressed about moving sea-ice do not apply in this case.

dp

Sorry – I misspelled refudiation, there.