Finding the Missing Player in Pleistocene Ice Age Discussions

[Andre]

In the NERC discussions and somewhere here in a thread I remarked that the great mysteries of the Pleistocene Ice Age cannot be solved without finding the "missing player"






We got him.

Anyone curious? I'm ready to discuss.

BTW my earlier threads about the role of clathrate for the extinction of the megafauna remains roughly valid, we're only one "why?" further. However Many "why's" to go before I sleep.

http://www.space.com/scienceastronomy/equator_bulge_020801.html

 

[billiards]

What the hell are you talking about?

 

[Andre]

So you still think that there is no problem or two or twenty with the hypotheses of the ice age? In that case we still need to do a little demolishion, like this fragment from the NERC discussions:

http://home.wanadoo.nl/bijkerk/refuting%20the%20Greenland%20paleo%20thermometer.pdf

I mentioned the missing player here: http://www.nerc.ac.uk/about/consult/debate/debate.aspx?did=1

I repeat, about a dispute of the role of the ocean floor; knowing what happened at the onset of the Bolling Allerod and the Preboreal is essential for understanding what had happened to the late Pleistocene climate after the switch to the 100ka world.

Did not ocean currents fluctuate strongly at those transitions? THC shut and acceleration have been proposed. But why? and why so abrupt, considering the gigantic inertia of that ocean flow. We know now that it was not the sudden temperature change at the onset of the Bolling since that happened 2000+ years earlier (long masked by not calibrating carbon dates).

Believe me, there is another player to be found, who also can explain the dying of the coral during the MWP1a, and the concurrent worldwide d13C depletion spike etc, and ultimately the extinction of the megafauna.

If you don't have all the players on the field, the models won't do any good. And when the picture is complete, the reason of the passive CO2 reaction will be obvious. But that's called paradigm shift, of which Thomas Kuhn has shown why it is so difficult to get that accomplished within a generation.

It's about that missing player

 

[sneez]

Andre, did you write or can cite a paper which would coherently describe and present your point and what you are trying to tell us here?

I am not an expert on climate so i would appreciate something explanatory and cohesive which i could read and understand. These links, and online discussions are just getting across ideas. That does not count much as anything without the proper work. To be honest i have only slight idea what you trying to say but i fail to see any connection to GW, glaciers, radiation, etc from those separate, unconnected links.

Would something like that be in your powers to write?

 

[verdigris]

You are saying,Andre,that people should not base current models of anthropogenic greenhouse forcing on Pleistocene data because CO2 data and radioisotope data from the Pleistocene do not agree.I have also read on Wikipedia that Milankovitch cycles cannot account for all the glacial-interglacial periods in the Pleistocene, on their own.Coral died in the Pleistocene because of something that changed in the deep ocean?

 

[billiards]

I have been reading papers all day, none of them made any sense!
(note: nothing to do with this discussion)
Why did I chose geophysics??

But yes, sneez is right, you're a specialist in a field that I personally have been to a few 1 hour seminars on/skimmed past in other reading. If you want us to make intelligent comments you need to give us something a little more solid, something that gives us the relevant background, and is accessible to someone who doesn't necessarily know all the nomenclature.

 

[Andre]

Okay that makes sense. It makes a difference talking to a quartenary specialist or somebody whose textbook says in two paragraphs that there aint no mysteries in the ice age.

I can cite loads of assumed facts that are proven wrong, papers that actually contradict but I don't think that anybody is waiting for that.

One of the major problem areas is the ocean. ocean flows are slow and the body of water has a tremendous inertia. Nevertheless, ocean ice age papers are all about shift ands quick reactions of the ocean to any changes. If you compare the deep sea bed sediment proxies with the ice core proxies, they are not only virtually identical but also it appears that the ocean could be leading. Nobody appears to think that is this weird.

Then there are the sea level problems. Only along the equator and for the last transition from the glacial there is some consistency in equatorial proxies but not elsewhere. That's even in the TAR of the IPCC. However strange things have happened before the former interglacial, the sea level rise appeared to be completed before the deglaciation started. There is plenty plenty more. I hinted to a few in several threads.

The most aggravating non consistency with any hypothesis is probably the reason why so many easy errors have been introduced like the fake 100ka Milankovitch cycle. Things need to be in an orderly explainable fashion, but they aint.

Here is the idea in a nutshell (let me know if there are difficult words in there):

Diagnoses of the Ice Ages: Pulsating Equator

Abstract

We demonstrate that if the size of the equatorial bulge would pulsate around an equilibrium in an irregular 100ka cycle and with some ten-hundred meters ROM amplitude, then it would explain most of the symptoms of the ice age. Periods of maximum equatorial bulge size represent interglacials with high sea levels due to relatively small oceanic basins. Periods with a minimum equatorial bulge have low sea levels due to equatorial enlargement of the Oceanic basins. Furthermore, during contraction of the equatorial bulge, the poles are pushed upwards to much higher elevations, both effects combined, increase orographic effects enough to trigger glacier growth at high latitudes, which accumulates in ice sheet build ups. In this scenario, the reverse process, with an expanding equator and sinking poles are leading to the interglacials, in which transient effects like Heinrich events, Dansgaard Oeschger interstadials, melt water pulses find an easy explanation.

http://home.wanadoo.nl/bijkerk/Pulsating-ice-age.pdf that may help visualizing what has happened, advise to use page down/up keys.

 

[Andre]

I also said: "And when the picture is complete, the reason of the passive CO2 reaction will be obvious"

And indeed, Verdigris, With this completely different picture in mind, it will be clear why I think that the role of CO2 for climate thoughout the Pleistocene was (and is) completely insignificant.

 

[billiards]

That's quite a neat little mechanism, have you checked the timescales? what kind of strain rates would you need, wouldn't there have been an increase in seismicity? have you run any computer simulations? have you published anything on this, I'd be interested in checking it out.

 

[Andre]

That's quite a neat little mechanism, have you checked the timescales?

Yes, course of events appear to match, but of course a lot of things need to be addressed

what kind of strain rates would you need,

It would be nice if specialist would be interested to judge that.

wouldn't there have been an increase in seismicity?

That would have been a neat prediction, if it wasn't for the puzzling volcanic activity peak during the last glacial transition we already know about. For instance both the German Eifel and the French Massiv Central, mostly dormant, had very active volcanism during that period.

have you run any computer simulations?

It's a pristine idea however with dazzling matches of geologic features.

have you published anything on this, I'd be interested in checking it out.

You're most welcome. A lot needs to be done.

first witness: The http://forams2006.micropress.org/gavriloffposter.rtf tells us when this mechanism started. These species could not cope with the dramatic changes in deep water waterflows which this mechanism triggered.

When things seems logical all of sudden, you know that you're on to something.

 

[verdigris]

ANDRE said:

"These species could not cope with the dramatic changes in deep water waterflows which this mechanism triggered"

What in particular did the stilostomella have trouble coping with - water temperature change,nutrient availability changing?

There is a nice photo of stilostomella here:
http://homepages.ihug.co.nz/~bw.hayward/images/plate3.jpg

 

[Andre]

Who knows. It's just likely that a typical darwian selection took place, when conditions changed, the species that were too specialized disappeared, while the most adaptable survived.

As mentioned, one thing that did change was isotopes captured by those creatures in the deep sea beds, almost exactly at the same time as isotopes of Antarctic ice cores like this:

http://home.wanadoo.nl/bijkerk/LR05-Epica-dome-c.gif

It could be suggested that the oceanic isotopes were leading the ice cores, although the error bars are rather uncertain and the dating methods may easily get into circular reasoning when time scales are tuned to each other.

However, ice sheets take centuries to millenia build up as can be derived from geologic data. This would determine the slope of the ice core proxies. However the THC circulation also takes more than a millenium to distribute that signal over the sea beds but also it mixes with the deep water so it would take even longer to get the ice build up signal to the deep sea. But it did not. The sea beds knew that the deglaciation started, practically before it actually did.

Consequently the idea that both those isotopes represent ice sheet build up is clearly wrong. Whatever it is, it started at the sea beds and now we can assume that it represent mostly currents generated by the pulsating equator

 

[verdigris]

ANDRE said:
"Whatever it is, it started at the sea beds "

What if material from the surface sank to the sea beds e.g plankton,because of a high mortality rate from ozone depletion at the poles and increased uv light.

 

[Andre]

Unlikely,

The d18O is measured from shells of identified foraminifera species which are bottom dwellers (benthic). Isotopes are usually considered temperature proxies. Since the temperature at those depth around 2-4km are rather constant, be at at the equator or pole, it is thought that these isotope spikes represent the actual isotope ratio of the deep water. Then it was recognised that the ice sheets have very little heavy isotopes due to the fractination of the physical processes involved (evaporation - condensation). So the idea was that the oceanic d18O ratio was a measurement for the amount of ice locked on the poles. A sort of distilling process.

However, if you consider the supposed global (eustatic) sea-level difference of ~125 meters then you're still about half a mil out of ~1,5 mil short of the required values, but you'd need already to put 15.4 Greenland ice sheets equivalents away somewhere. There is not too many room for that on Antarctica, already loaded with ice, perhaps 2-3 ice sheets. North America can have some 5-6 Greenland ice sheets equivalents before it is filled up like it was at the height of the last Wisconsan ice age. So we need to tuck away ~7 Greenland ice sheet. No problem: in the 1980ies when this was all invented; there was a large and very unknown Siberia, lots of space out there. Plenty for so many Greenland ice sheets.

It was not before the turn of the century when the researchers were allowed to swarm over that area that it became clear that had been no ice on Siberia at all during the Last Glacial maximum. http://home.wanadoo.nl/bijkerk/eurasian.jpg , perhaps just enough for two Greenland ice sheet equivalents.

So I still have about 5 Greenland ice sheets left to stow away somewhere and that only covers the ~120 sea level change, not enough to balance the isotopes. That would have required some 20.2 Greenland ice sheet equivalents in total as well as a sealevel lowering of 164.5 meters which is not attained anywhere except perhaps for a certain lost Cuban city.

So both the sea level yoyo as well the isotope balance hypothesis (Rutherford) do not match the actual numbers and can be considered falsified. Not that they are considered that, it's still used every day because it's the best there is perhaps.

 

[Andre]

Looking again http://home.wanadoo.nl/bijkerk/eurasian.jpg it appears that the bulging reaction of the North Pole was not symmetrical. Plenty of ice on N-America, little ice in the east.

Now, a little bit more to the East, just off the map at #1 the Laptev Sea, close to the coast, the Yukagir mammoth was found, with a calibrated age of some 22,000 years, just at the onset of the Last Glacial Maximum. As I elaborate upon http://home.wanadoo.nl/bijkerk/refuting%20the%20Greenland%20paleo%20thermometer1.pdf in his intestine were remains of the greater burnet, a herb with limited winter hardiness, basically trashing the ice age idea.

Now if we assume orographic effects, Scandinavia way above sea level in a less elliptical world then there would not be a requirement for Siberia to be that much colder because evidently it was warmer then as today.

Interesting study:

http://www.advances-in-geosciences.net/1/103/2003/adgeo-1-103-2003.pdf

 

[billiards]

Nakada et al. 2000 gives a current rate of isostatic rebound for the continent of Antarctica as 1.7 mm yr^-1. I don't know how long you propose these cycles take, I guess between 10,000 - 100,000 yrs. Which if we take the current rate and be a little generous, let's say 2 mm yr^-1 you're getting about a 20 - 200 m change in elevation over those time scales. I guess maybe you'd have to half that to find the amplitude of a cycle, so maybe 10 - 100 m actual elevation change. Do these changes seem reasonable? Could they account for the orographic effects you mentioned?

 

[verdigris]

ANDRE said:
"However the THC circulation also takes more than a millenium to distribute that signal over the sea beds "

Why does it take this long? Are you talking about the entire surface of the sea bed around the world?


ANDRE said:
"Consequently the idea that both those isotopes represent ice sheet build up is clearly wrong. "

Perhaps not - if the ice sheets built up in the sea around Antarctic.
Then the weight of ice on water would influence currents and the flow of information just as the Odden feature does in Greenland.I have also read that Stilostomella thrive when the carbon flux is high.In a colder climate with low biomass - and low carbon flux - the stilostomella could have been starved and the increased sea water salinity may have killed them.Also the circumpolar current would have been weak because of less wind energy in the atmosphere.This would have helped ice to form on the sea.

At this link: http://www.space.com/scienceastronomy/equator_bulge_020801.html
Christopher Cox suggests that shifting ocean currents can account for the pulsing equator.Would this also account for the satellite orbital anomaly of 1998 (there were also anomalies in 1985 and 1989)?

 

[Andre]

Nakada et al. 2000 gives a current rate of isostatic rebound for the continent of Antarctica as 1.7 mm yr^-1.

Isostatic rebound it a local process with tops at the North Baltic sea of 9mm a year. The pulsating equator would probably match that order of magnitude, seeing the speed at which equatorial sea levels change, say 120 meters in 12,000 years. Half of that probably to balance the water captured in the ice sheets, the other half for pulsating. Just ballpark figures. Mind that in a perfect ellipsoide for each procent that the equator bulges, the poles have 1,96% change, so that would be around 120 meters for bulging out and some more for the sea level lowering when the oceans rebalance. Seeing the difference of the Scandinavian and North American ice sheets versus the productive Siberian Mammth steppe, then it is clear that the actual situation is less than symmetrical. But I have yet to see another attempt to approximate a possible mechanisme that could explain those differences.

I don't know how long you propose these cycles take, I guess between 10,000 - 100,000 yrs.

It appears to be a very irregular cycle, but we cannot possibly says which part of which proxy is result of which effect. N equations with M variables and M >> N for the moment.

I guess maybe you'd have to half that to find the amplitude of a cycle, so maybe 10 - 100 m actual elevation change. Do these changes seem reasonable? Could they account for the orographic effects you mentioned?

I gues that the average total change - geoide - ellipsoid form change plus resettling sea level is ROM 120-200 meters. That's good for for max 1,3 degrees in a standard atmosphere. Doesn't seem much, we need local effects. Some more elevation change at some places than others. You need only a few domes to generate glaciers, plenty available in Scandinavia and NE Canada.

other evidence is the volcanic tracer proxy at the Greenland ice cores showing "high activity during the climate changes"

http://www.gisp2.sr.unh.edu/Contri_Series/full/09.html

How would the East African rift valley fit in the scenario?

 

[Andre]

ANDRE said:
"However the THC circulation also takes more than a millenium to distribute that signal over the sea beds "

Why does it take this long? Are you talking about the entire surface of the sea bed around the world?

The benthic stack of which I'm talking, check the paper here:

http://www.maureenraymo.com/2005_Lisiecki+Raymo.pdf

Data of 57 different stacks at evenly divided over the world, all show the same. The THC needs some 1500 years to complete a cycle, where is the difference? The isotopes of the benthic stacks should register both the slow change in ice accumulation, the slow distribution if isotope ratio change and the slow mixing process. They show none of the latter two.

Sorryu someone is hovering around to take over thisd computer. Back later

 

[verdigris]

How do we know the thermohaline cycle takes 1500 years?
It's interesting to note that one of the mass extinctions of foraminifera targeted cylindrical forms in particular.
This link gives some ideas researchers have about foriminifera extinction:
http://homepages.ihug.co.nz/~bw.hayward/index.htm

During the Pleistocene glacials there were "pluvials" in which hot parts of the world got a lot of rainfall.Perhaps the surface currents in tropical regions became too warm and killed coral - and coral fragments sank from the surface and carried calcium carbonate to the deep sea,the calcium carbonate then becoming part of the foraminifera shells.This could account for the absence of a delay between the ice-sheet and benthic isotopes.

 

[billiards]

Furthermore what is a THC cycle??

Another point of interest that I inadvertantly stumbled upon is that apparently (according to recent satellite data), the Antarctic ice sheet is growing, at the same time, the continent is rebounding, how do you explain that?? To me it suggests a very slow response time to changes in the ice load, there is a lag. I know you're dealing with the other hemisphere, but presumably the mantle viscosity is not so different up there and a similar lag occurs. I suppose it begs the question, are these very long period oscillations a side-effect, a cause, or both, wrt the changes in ice load?

 

[verdigris]

BILLIARDS said:

"the Antarctic ice sheet is growing, at the same time, the continent is rebounding"

Could just be the fact that mass takes time to respond to a force i.e the weight of ice.

 

[Andre]

Point here as well is that Greenland is subsiding. This may be due to an accelleration in ice accumulation as the Holocene precipitation is roughly 3 times more than during the last glacial period. But this is also true for Antarctica. On the other hand the North West Territories and Labrador are also rebounding so it may be a combined event.

But picture this, geologic remains reveal that parts of Scandinavia were ice free around 40,000 years. The was most certainly not a big ice sheet at that time. Then at some point the last glacial advance, the late Weichselian started and accumulated until 20,000 years ago. How deep can an ice sheet grow in and decline in 20,000 years. Say 10,000 years to grow, 5000 in steady state and 5000 for ablation. Greenland would have reached about 1500 meters on the summit after 10,000 years. So you can mage that the situation for isostatic depression is rather limted. Neverheless, the current isostatic rebound up to 9mm a year appears to be very large compared to that.

Could the rebound also be related to pulsating poles and the following unbalance?

 

[billiards]

You'd need a mechanism to explain why the poles were pulsating. Presumably it's because of the ice load, body wave seismology and general spherical harmonic analysis suggests that the fundamental period of the Earth's oscillation is (from the top of my head) about an hour or two; therefore any longer period oscillation must be forced by some external mechanism.

 

[Andre]

About 90 minutes, indeed. How about a waxing and waning inner core?

Earth looses geothermal heat -> core looses energy -> outer core material solidifies to the inner core -> Inner core increases in size -> gains annular momentum -> increasing strain on stabilisation mechanism of the spin axis of the inner core -> additional friction (see Vanyo) -> more heat -> inner core melts to original size.

A more or less fluid inner Earth may have effect on it's geoide shape or do we need more miracles?

 

[billiards]

It's an interesting thought: does the inner core spin at the same rate as the mantle? Of course we don't know, our best chance of finding out is by looking at seismic inhomogeneities in the core and to see if they move with time. Of course, we have only recently been able to detect seismically slower/faster regions in the core, it's very difficult to invert the data from down there, and we will need to monitor it over a long period before we can see any observable effect.
If the core is spinning at a different rate then I guess there'd be more shear (especially at the 'equatorial' inner/outer core boundary) and a better chance for your mechanism to work, of course the viscosity would have to be high enough to cause frictional heating (which if I'm thinking along the right lines would actually be maximum halfway between the CMB and the IOB - which won't really help melting the inner core) and I'm not sure that'd be the case given that the inner core is liquid. But even if it works, then why would it oscillate? Why wouldn't it just reach a steady state?
Which then leads to your last point, what effect will a waxing and waning inner core actually have on the Earth's shape anyway?

 

[Andre]

We have some hints about the inner core spinning faster:

http://www.nsf.gov/discoveries/disc_summ.jsp?cntn_id=100044&org=NSF

Excellent seismic discoveries.

The point here is not about lateral motion but alignment of the inner core spin axis with the mantle spin axis, given that torque forces of precession / tilt cyles act differently on the mantle than on the core. The size of the inner core would be a very important parameter. There should be a tendency of the core spin axis to precess away. That would cause some strain in the fluid outer core. I was trying to give that hint in the other thread where we digressed to Venus. Same story but on a much much larger scale.

So while the cores and the mantel were fighting each other, Earth's shape could be affected. Reminds me of a cartoon.

 

[verdigris]

ANDRE said:
"So you can mage that the situation for isostatic depression is rather limted. Neverheless, the current isostatic rebound up to 9mm a year appears to be very large compared to that."

The crust is probably not uniform and therefore the isostatic rebound rate sensitive to where the load is being placed.

ANDRE said:
"There should be a tendency of the core spin axis to precess away. That would cause some strain in the fluid outer core."

How do we know that a change in the mantle didn't cause the strain in the outer core.Is this inconsistent with the data?

 

[Andre]

ANDRE said:
"So you can mage that the situation for isostatic depression is rather limted. Neverheless, the current isostatic rebound up to 9mm a year appears to be very large compared to that."

The crust is probably not uniform and therefore the isostatic rebound rate sensitive to where the load is being placed.

ANDRE said:
"There should be a tendency of the core spin axis to precess away. That would cause some strain in the fluid outer core."

How do we know that a change in the mantle didn't cause the strain in the outer core.Is this inconsistent with the data?

Basically we don't know anything. We speculate. That's how it worx. You have a jig saw puzzle with many many pieces and you have no idea what its depiction is, you have to figure it out by yourself. So you start speculating. Perhaps it is this, and with that picture you start fitting the pieces. You can be quite sure that you're first idea is wrong. So soon after starting the pieces don't want to fit in anymore.

Now there are two posibilities, you don't accept it, because you cannot affort defeat, and continue to both squeeze in the pieces by force and ignore the ugly pieces that don't fit in at all, or you tear the whole thing apart and start all over again. Any idea how many times I started all over again?

So you think perhaps the puzzle is about a pulsating equator, so we start fitting to pieces again and this fits, and this fits, and some of those ugly categorically ignored pieces also fit. So the question is, when will we find not fitting pieces and what are we going to invent next?

But if all pieces fit in reasonably well, your next problem is the "why" question.

 

[Andre]

Another piece of the puzzle, the CO2 levels. As has been made abundantly clear, low levels in the glacial periods, high levels in the interglacials. So CO2 is invariably tied to temperatures and hence greenhouse effect but is this logical?

Have a good look here at http://earthobservatory.nasa.gov/Library/CarbonCycle/Images/carbon_cycle_diagram.jpg.

See all the cycles? Cycles like this tend to find an equilibrium proportional to the ratio of the capacity of the reservoirs. The large reservoir of the deep ocean is a dominant factor here. This is a bit temperature depending, but with a deep ocean on a steady temperature, currently equal at poles and equator, the capacity of the deep sea does not change so much with surface temperature.

The pulsating equator causes variability in the size of the deep ocean. During round Earth glacials there is more deep ocean reservoir which will tend to shift the balance between the various reservoirs towards the oceans, consequently, less CO2 in the atmosphere. The reverse happens in the more elliptical interglacials where the deep ocean reduces in size and has to vent out CO2 to the other reservoirs, hence more CO2 in the atmosphere.

Greenhouse effect? I think not.