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Andre

Finally, the "water" isotopes in the ice cores

This is the short abstract of the article which refutes the water isotopes in the ice cores as thrustworthy paleothermometers and something more to demonstrate that our knowledge of the Pleistocene ice ages is still very marginal:

Quote:
The current scholarly view about climate change is based upon paleoclimate data, mainly from the late Quaternary. It is perceived that these proxies show that the Earth's climate is remarkably sensitive to global forcings. Positive feedbacks appear to predominate. It seems that this allows the entire planet to be ‘whipsawed’ (sic) between climate states (Hansen et al., 2007). The main data for these speculations are provided by ice cores, storing and accumulating both atmospheric gases and precipitation over at least the last 400,000 years, and these data are considered the archives (proxies) of the past. The ice cores show an apparent strong correlation between temperature reconstructions from isotope ratios and carbon dioxide concentration. But several inconsistencies have been identified, notably for the period 17,5-14,5 Ky, known as the Mystery interval (Denton et al 2006) and the Younger Dryas between 12,7 and 11,6 Ky.

Here we demonstrate that many of those discrepancies can be explained when the temperature interpretation of the ice cores is abandoned. Instead, we propose that the ice core isotopes are a main proxy for rate of snowfall or lack of it, obscuring temperature signals, which appear much more stable than currently thought. This also casts a whole new light on the presumed feedback factors and the cause of events during the last glacial transition. We demonstrate that the role of the oceans is truly enigmatic, which would require an exceptional mechanism for its explanation.


The "Younger Dryas exhibits" have revealed that the Younger Dryas was not about extreme cold conditions with massive advancing ice sheets. Instead we see abrupt changes between moist climates to widespread arid conditions and back. Here we show why this is also the message of the water isotopes of the Greenland ice sheets.

Three reasons for that, variations in seasonality of precipitation rates, changes in rain out (Rayleigh effect) and decreased dew point temperatures in arid conditions.

Which one first?
Andre

In the carbon dating thread I have elaborated a bit about fractination of isotopes during transitions. Same goes for water:

http://wwwrcamnl.wr.usgs.gov/isoig/res/funda.html

or

http://wwwrcamnl.wr.usgs.gov/isoig/isopubs/itchch2.html

and

http://wwwrcamnl.wr.usgs.gov/isoig/isopubs/itchch2.html#2.3.1

Quote:
During phase changes, the ratio of heavy to light isotopes in the molecules in the two phases changes. For example, as water vapor condenses in rain clouds (a process typically viewed as an equilibrium process), the heavier water isotopes (18O and 2H) become enriched in the liquid phase while the lighter isotopes (16O and 1H) remain in the vapor phase. In general, the higher the temperature, the less the difference between the equilibrium isotopic compositions of any two species (because the differences in ZPE between the species become smaller).


So let's follow an air mass generating water vapor from the ocean. The first process we encounter is the fractionation of the water molecules during the evaporating, interestingly enough we see:



Quote:
Evaporation from an open-water surface fractionates the isotopes of hydrogen and oxygen in a manner which depends on a number of environmental parameters, the most important of which is the ambient humidity.


Evidently, the more arid the stronger the fractionation, hence in low humidity conditions the water vapor is already more depleted in heavy isotopes than under moist conditions.

Then the airmass transports the water vapor towards the ice cores, normally from warmer lower lattitudes to the cold arctic cores. hence the air cools and condensation takes place, with fractination again, the heavy isotopes go first depending on temperature, the colder the stronger the fractination. Since condensation is occuring at 100% relative humidity, this process is not humidity dependent, or is it?

are we overlooking something here? How is the temperature defined at which condensation takes place. What do we know about that?

Everybody still here?
scpg02

I keep trying to comb my hair up higher so this stuff will stick.
Andre

great, I try to make this understandable for myself and others. Hoping that it helps in formulating the paper. So, if it sounds like Chineese please do tell and I'll try and rephrase.

Back to the condensing temperature, it is called "dew point"

Quote:
The dew point (or dewpoint) of a given parcel of air is the temperature to which the parcel must be cooled, at constant barometric pressure, for water vapor to condense into water, called dew. When the dew point temperature falls below freezing it is called the frost point, as the water vapor no longer creates dew but instead creates frost or hoarfrost by deposition. The graph to the right shows the maximum percentage of water vapor that can exist in air at sea level across a range of temperatures.




Consequently, the amount of water vapor in the air determines at what temperature condensation starts. The drier the colder. We also know that the temperature in the lower atmosphere has a lapse rate, the higher the colder. So if at the same surface temperature drier air convects to form clouds and rain this will happen at an higher, colder altitude than when moist air convects with clouds and rain. But whilst the surface temperature is assumed to be equal in both cases, the isotope signature of the drier air at lower dew points is more enriched with heavy isotopes than the moist air at higher dew points.

Pausing here to think about that.
HighPlanesDrifter

Re: Finally, the "water" isotopes in the ice cores

Andre wrote:
This is the short abstract of the article which refutes the water isotopes in the ice cores as thrustworthy paleothermometers and something more to demonstrate that our knowledge of the Pleistocene ice ages is still very marginal:

Quote:
The current scholarly view about climate change is based upon paleoclimate data, mainly from the late Quaternary. It is perceived that these proxies show that the Earth's climate is remarkably sensitive to global forcings. Positive feedbacks appear to predominate. It seems that this allows the entire planet to be ‘whipsawed’ (sic) between climate states (Hansen et al., 2007). The main data for these speculations are provided by ice cores, storing and accumulating both atmospheric gases and precipitation over at least the last 400,000 years, and these data are considered the archives (proxies) of the past. The ice cores show an apparent strong correlation between temperature reconstructions from isotope ratios and carbon dioxide concentration. But several inconsistencies have been identified, notably for the period 17,5-14,5 Ky, known as the Mystery interval (Denton et al 2006) and the Younger Dryas between 12,7 and 11,6 Ky.

Here we demonstrate that many of those discrepancies can be explained when the temperature interpretation of the ice cores is abandoned. Instead, we propose that the ice core isotopes are a main proxy for rate of snowfall or lack of it, obscuring temperature signals, which appear much more stable than currently thought. This also casts a whole new light on the presumed feedback factors and the cause of events during the last glacial transition. We demonstrate that the role of the oceans is truly enigmatic, which would require an exceptional mechanism for its explanation.


The "Younger Dryas exhibits" have revealed that the Younger Dryas was not about extreme cold conditions with massive advancing ice sheets. Instead we see abrupt changes between moist climates to widespread arid conditions and back. Here we show why this is also the message of the water isotopes of the Greenland ice sheets.

Three reasons for that, variations in seasonality of precipitation rates, changes in rain out (Rayleigh effect) and decreased dew point temperatures in arid conditions.

Which one first?


Hi Andre,

New guy here.

Sorry to be so pedestrian, but I am somewhat confused. Is his an abstract of a published article or an unpublished article? If the latter is it an article you are in the process of writing based upon your posts in Younger Dryas exhibits?

Thanks, HPD
Andre

Hi HPD, and welcome to our small world.

No, the article is work in progress. I should have been more clear on that. Just trying to get the required feedback, discussions, etc.

Publishing is something different of course. It will be very interesting to see the mechanisms of Thomas Kuhn in action, trying to sell this story.

I'll resume the narrative shortly
Andre

OK resuming,

We have seen that under arid conditions during the evaporation the water vapor gets more depleted with heavy water molecules (DHO or H2-18O). Then due to a lower dew point the condensation (at higher altitude and lower temperatures) favors the heavy isotopes, forming clouds and rain.

So the first rain to fall is the heaviest in water isotopes, leaving behind water vapor with less heavy isotopes. So when the air mass progresses to the ice sheets and cools further this process continues, raining out more heavy isotopes and leaving less and less heavies in the air mass. And this effect, the so called Rayleigh effect, is stronger in arid conditions. Something like this:

Moist conditions:



Arid conditions:
Less heavies evaporating.
Clouds higher and colder.
Stronger rain out effect of the heavies.
Much stronger depleted water reaches the poles on the right:



So during the arid "mystery interval" and the Younger Dryas we find much more strongly depleted isotopes in the ice cores than during the wet periods before and after. But we never changed ambient temperatures to get that effect.
Andre

Next is seasonality of precipitation. We have seen already here that Jouzel et al considered seasonality but rejected it because of some model:



This is how seasonality works, a shallow ice core in the GISP project, only the top few meters with several isotopes samples per year from 1940Ad to 1985AD gives this:



See the strong annual oscillation? higher values in summer time and lower values in wintertime? Obviously the dewpoints are much lower in the winter. Clearly the seasonal cycles appear to represent temperatures. The only problem is that the trend is not in accordance with the local/global temperatures.

Then of course, there is also the relationship with precipitation rate. The Snow season is summer. In the winter it is too cold to snow. So what would happen when the summer is arid for some reason all of a sudden?
billiards

Hi Andre, I've finally had time to do a bit of reading here.

I was wondering if you could paraphrase the "standard model" for us (me). It's not something I had the fortune to be taught properly at uni, although my impression of it was that a lot of the interpretation was based off of what was going on at the other end of the water phase change i.e. you are considering water from liquid <-> gas, whereas I was under the impression that it was the liquid <-> solid phase that was really important here. Something to do with the amount of ice around, which in theory should be compatible with sea level data (working on the assumption that more ice = lower sea level) - presumably people have studied these things?
Andre

billiards wrote:
Hi Andre, I've finally had time to do a bit of reading here.

I was wondering if you could paraphrase the "standard model" for us (me). It's not something I had the fortune to be taught properly at uni, although my impression of it was that a lot of the interpretation was based off of what was going on at the other end of the water phase change i.e. you are considering water from liquid <-> gas, whereas I was under the impression that it was the liquid <-> solid phase that was really important here. Something to do with the amount of ice around, which in theory should be compatible with sea level data (working on the assumption that more ice = lower sea level) - presumably people have studied these things?


You tough a lot of things here. I had a thread or two in mind about the relationship between ice core isotopes and marine isotopes, the sealevel - ice sheet balance and why it doesn't work.

Here is some more background on water isotopes.
HighPlanesDrifter

Hi Andre,

you wrote:
Here we demonstrate that many of those discrepancies can be explained when the temperature interpretation of the ice cores is abandoned. Instead, we propose that the ice core isotopes are a main proxy for rate of snowfall or lack of it, obscuring temperature signals, which appear much more stable than currently thought. This also casts a whole new light on the presumed feedback factors and the cause of events during the last glacial transition. We demonstrate that the role of the oceans is truly enigmatic, which would require an exceptional mechanism for its explanation.


Wouldn’t the relative thickness of the compressed ice layers be a natural proxy for the measure of annual snowfall? Don’t paleoclimatologists measure this? If so how does it compare to your theory?
Andre

Hi HPD,

HighPlanesDrifter wrote:

Wouldn’t the relative thickness of the compressed ice layers be a natural proxy for the measure of annual snowfall?


Most certainly. Apart from the pressure deformation there is also consideration for evaporation/sublimation/melt, etc during the deposit of the snow.

Quote:
Don’t paleoclimatologists measure this?


Certainly they do, the initial layers are visually identifyable, then when it's compressed to solid ice, there are still faint annual dust layers, also the conductivity varies througout the seasons. But lower down the layers get so thin that they are no longer recognisable, then all kind of Volcanic tracers are used to link to known events, so set fixed dates at certain positions, but then you'd have to make assumptions about the variation in annual accumulation again.

In the case of the last glacial termination at Greenland, establishing the annual snow accumulation, the layers were countable and the construction could be made with fair confidence.

Quote:
If so how does it compare to your theory?


Reasonably awesome, after the explanation how arid conditions cause lower isotope ratios in the ice cores, due to stronger rayleigh effect and given the massive supporting evidence for arid conditions during the Younger Dryas this graph should be no surprise:



Top is reconstructed annual accumulation, middle graph is the oxygen isotope ratio (d18O) of the ice. The lower graph show that methane also joined the concert. More about that later.

Let's finish the seasonality thinghy first. Look again at the shallow core:



See that the highest amplitude of the annual isotope spikes are in the freshest part, when the compression start the ice mixes and the spikes slowly dissapear. After about 10,000 years in Greenland the annual spikes are completely gone and the isotopes show the annual average. But that's not the same as the middle value in the graph. Simply because of the seasonality of precipitation. If there is much "warm" summer snow then, against the little "cold" winter snow accumulation the weighted average is towards warmer. So if much of the warm summer snow stays away in the Younger Dryas and the cold winter snow remains unchanged then the weighted average is towards colder. In this case seasonal rate change of precipitation determines warm or cold.

Below is a small demonstration of that effect: This little model is resembling a smal horizontal piece of the ice core on an accumulation scale as it would have actually looked uncompressed during the transition of the Younger Dryas to the preboreal, just like the shallow core above albeit on a time scale. The blue oscillation resemble the seasonal fluctiation in isotope ratio. The Younger Dryas part shows thin annual accumulation, the Preboreal much thicker in the high part, with wet summers. The thick black line represents the weigthed average.



Now after 11,600 years of compression that same piece of ice core may look like this:



The seasonal variation has faded due to compression mixing and what remains is the thick average line to be measured by the ice core specialists. This is how you can get that spike

This all means that the isotope variation can be explained by variation in aridness and seasonality of precipitation, which means that the evidence is used up. Hence, the isotopes cannot be a proxy for temperatures as well, and this is the essencial objective of this thread, to demonstrate that these isotope spikes are not 10-15 degrees temperature variations that all scholars prescribe. No flickering climates. This is wrong:



The red (isotope based) graph merely repeats the blue accumulation graph, hence it is no temperature. You can't use evidence twice.
Andre

But we are far from done yet.

Firstly, the ice core isotope study is not limited to water isotopes as well. Jeffrey Severinghaus et al develloped an ingenious hypothesis to cross check temperatures with other fractination processes (thermal and gravitational) with other isotope ratios in the captured air of the ice cores, notably 15N (heavy nitrogen) and 40Ar (heavy argon). They find behavior consistent with temperature differences. That's a tough one to beat of course.

However, supporting hypotheses are not proving other hypotheses, that's not how the scientific method works and when empiric evidence shows otherwise, then the case gets pretty weak. Moreover, why couldn't these processes be consistent with seasonal precipitation variation as well? I can imagine that the absence or presence of summer snow has consequences for the captured air in the snow and it's temperature profile.

Secondly, consistency is nice but we need to quantify things as well. So, we should build a little demostration model, juggle with deuterium excess and meteoric water lines to demonstrate whether or not aridity variation is consistent with all the data. But unfortunately, I'm not a paleo-isotope-hydrologist. So, I seek help of such a specialist. Would anybody happen to be, or to know such a person, whom on top of that would appreciate some sceptism about our understanding of the climate in the past?

Thirdly, how about Antarctica? I guess that's worth another thread.
HighPlanesDrifter

Hello André,

Thank you for your prompt response to my previous question indeed there does seem to be a correlation between 18O and precipitation in the GISP2 cores over displayed period.

Forgive my slowness to respond as climatology of any kind is not my specialty and it takes me awhile to digest your posts and reexamine other threads to find the answer to my questions. I am trying to prevent having you repeat yourself.

I find your arguments are interesting, but I will find them more compelling after they have been reviewed by others that are more knowledgable than myself in this area. After all, isn’t the “Younger Dryas” named after the pollen of an alpine flower that would not have been expected at such a low altitude if it had not been a cold period?

HPD
Andre

Hi HPD
HighPlanesDrifter wrote:
I am trying to prevent having you repeat yourself.


No problem there, the essential things can't be shown often enough.

HPD wrote:
but I will find them more compelling after they have been reviewed by others that are more knowledgable than myself in this area.

That's standard I suppose. However, picture this: you're watching an unknown game between two clubs. At the end there seems to be a quarrel about who has won. How to find out which club should have? Ask a supporter of club A or B or ask the referee? Or study the rules (no need to play the game) and see for yourself that the referee was biased?

Here is a replay of one of the goals:

Hubberten et (21) al 2004 The periglacial climate and environment in northern Eurasia during the Last Glaciation, Quaternary Science Reviews 23 (2004) 1333–1357



Note: time scale in carbon dates vertical to resemble the orientation of the sediment core (bad habit).

Original caption:
Quote:
Fig. 6. (pag 7) Summer climate changes and the dated record of mammals in the Laptev Sea area (from Sher et al., in preparation). (a) Fossil-insect record in the Mamontovy Khayata section, Bykovsky Peninsula. Percentage of selected ecological groups of insects (minimum number of individuals in each sample equals 100%):
Thermophilous xerophiles:
1—steppe species;
2—other xerophilous insects (except tundra ones); Insects, currently common in tundra:
3—dry tundra inhabitants (prefer warmer sites);
4—Arctic tundra insects (plotted from the right axis).
14C ages in the left column are calculated from two separate regression equations after about 40 AMS dates. (b) Climatic and environmental interpretation of the insect assemblages from the Mamontovy Khayata section. (c) Radiocarbon dates of mammal bones from the Laptev Sea area (number of dates in 2500-year intervals). The latest available dates for mammoth and horse are indicated at the top.


See the transition between LWI coldest tundra steppe and LWII warm tundra steppe at 15,000 carbon years ago? Would seem to dovetail nicely with Greenland (Isotope "warming" spike starts at 14500 years BP), if it wasn't for one essential rule of the game: calibration. 15,000 carbon years calibrates to 18,500 calendar years BP, showing the real goal where the bal went in. No need to play the game, just know what to observe.

HPD wrote:
After all, isn’t the “Younger Dryas” named after the pollen of an alpine flower that would not have been expected at such a low altitude if it had not been a cold period?


I'm still trying to find that pollen core back that demostrates massive pollen of the Dryas octopela during the Younger Dryas. This is the best I could do:



These are the pollen profiles of six lakes in South Sweden, from the Bolling Allerod to the Holocene. Timescale vertical again but in actual calendar years (counted layers - varves) and compared with the time scale in Greenland.

Obervations:
1: There was no ice sheet on South Sweden anywhere in this period.
2: The only indication of "Dryas" (orange) is in the period G1-1D (B2) around 14,000 cal years BP corresponding to the Oldest Dryas. Nowhere else, including the Younger Dryas, was Dryas abundant enough to use it as marker species.
3: Empetrum is a typical wetland arctic tundra genus. I have all Empetrums marked in Yellow, to find out that it only was abundant before, and after the Younger Dryas, (orange on the time scale) suggesting that the Younger Dryas was not about wet (sub) arctic conditions as it was before and after. With Poacea (grass) Salix and Juniperus it resembled steppe with trees, not the coldests of the periods.

I keep looking for the abundant Dryas pollen during the Younger Dryas but apparantly not in Sweden, where the discovery seemed to have been done.
HighPlanesDrifter

Except that…I am only seeing the replay angles that you show me.

A few years ago I lived within walking distance of reading all the journals. I could check to see if there were further discussions on the papers you post, I could check to see if they had been cited further and who may have challenged their findings (and why). You and I are both aware of the number of papers that are later discredited or modified in one way or another.

Now I live in a very rural area. The Berkeley libraries are almost 200km away. My ability to check resources is limited.

There are many hungry researchers like you. They keep the system honest. By waiting for peer review I am not going to the other team, I am waiting for the system to work, and it will, sometimes it takes a while.

Suggestions for getting your papers accepted: Back off on the absolute conclusions and the sarcastic remarks. They’re fine for the internet where you have a receptive audience, but in the professional circles they will just make your findings harder to accept by the audience you want to influence.

If english is not your first language I must complement you. Yours is better than mine. Laughing

Carry on. Wink
Andre

HighPlanesDrifter wrote:
Except that…I am only seeing the replay angles that you show me....You and I are both aware of the number of papers that are later discredited or modified in one way or another.


Certainly, ultimately one should proof the pudding oneselfs. Reproduction is the name of the game and confrontation of findings using different methods.

Therefore, I have uploaded a simple PDF with the current reference list of the paper. (internal links don't work, I'm afraid). it should give a bit of an idea about the extent of the research. You can find it when clicking that funny grey square at the bottom of this post.

Quote:
Now I live in a very rural area. The Berkeley libraries are almost 200km away. My ability to check resources is limited.


Don't we have internet nowadays and networks. There are various ways to find out which publications you want to see and there are various ways to bypass/avoid closed doors legally. I have accumulated a few tons of PDF's that way.

Quote:
There are many hungry researchers like you. They keep the system honest. By waiting for peer review I am not going to the other team, I am waiting for the system to work, and it will, sometimes it takes a while.


I have experienced a peer review once. There appears to be a strong not-mainstream-hence-wrong tendency. There is also the complication of trespassing on the terrains of a few dozens specialities. Typical remarks are in the spirit of: while I concede the exsistence of some problems on my terrain, I'm sure my neighbour has everything in order.

Quote:
Suggestions for getting your papers accepted: Back off on the absolute conclusions and the sarcastic remarks. They’re fine for the internet where you have a receptive audience, but in the professional circles they will just make your findings harder to accept by the audience you want to influence.


Most certainly we will, thanks. The message is bitter, anyway. Try to imagine the consequences for geology for the paleothermometer being refuted. And that's not all, for instance there is another rock solid hypothesis about the concerted sealevel- ice sheet volume - maritieme istopes yo-yo..

The idea was born in the time when Siberia was unkwown forbidden land and to balance the yo-yo, it was dead easy to put a large ice sheet on it. But, instead of the ice, the mammoths and horses roamed the dry snowless steppes. Dozens of independed papers about details for that, not a single publication about the non existing morenes of the last glacial maximum. There is another serious threat for mainstream waiting to be exposed.

Quote:
If english is not your first language I must complement you.


Thanks, however, since you found out that it's not my mother tongue, there is still room for improvement.


Click to download file
HighPlanesDrifter

Andre,

A I mentioned before; you have produced some good agreements, I can not easily poke holes in them. You know more about the topic than I do. I also concede that there is a bias against scientists that challenge the status-quo. I also believe that at least part of the status-quo will some day be proven to be wrong. I have seen this in my lifetime. All of these points are admittedly to your credit.

There is a quote that I like a lot. Unfortunately I cannot easily find it now. I read it in one of John McFee’s books found in Annals of the Former World. He got it from someone who attributes it to an engraving over the doorway in an old German naval academy. It goes something like this: “Say not: ‘This is truth’ but say: ‘This is as it appears to be now, knowing what we now know.’”

I will keep my mind open on this topic.

Thank you for not taking too much offense at my comments. Facing peer review once is more times than I have faced it.

Admittedly I do not have enough interest in this topic to put extensive effort into bypassing copyright restrictions to verify the validity of your points. My knowledge of circuitous methods to do so is not as extensive as yours. In the past I have relied upon schools, libraries and places of employment to obtain this kind of information. I no longer have these at my easy disposal. Yes, I have the internet, but without proprietary access it is of limited use in these matters.

I believe that for a lay person to accept your posts at face value would be more of an act of bias than accepting the status quo. It would also be disrespectful of the scientific process .We both know how things can be manipulated. I am not accusing you of being anything less than honest and dedicated. I do not know you however, so for me to make that assumption would be an act of faith. I have been burned too many times to make that mistake again. I regret placing these restrictions on you but I feel they are prudent.

I will continue to read your posts with interest.

I would never have guessed english was not your first language if it had not been for your forthrightness with your location.

HPD
HighPlanesDrifter

One other minor point (this may have pertained to a different thread)

Although the current emphasis on Climate Change concerns “anthropogenic global warming” I believe that the term is actually more encompassing than that. I don’t see how you can deny a “flickering” of the climate (of the GISPII associated region) on the basis that the “flickering” may involve only a potential temperature change and not precipitation variations. Even if you are right about the temperatures remaining constant and the isotope variation being explained by both annual and seasonal changes in precipitation there would still be an apparent flicker in the climate based on precipitation IMO.

The denial of a climate “flicker “in this case would appear to be more of an attack against Hensen (et al) than to be one based on the actual denial of any climatic flicker.

Since the effects of the Younger Dryas seem to be most prominent in the North Atlantic region I could see one arguing against the effects of the YD being truly global. I would not be surprised if they represented a significant change in our planet’s jet streams rather than a truly “global” phenomenon. (if one can separate a large scale multi-millennial change in the northern hemisphere jet stream as not being global).

Personally I find the latest research that indicates that it may have been due to a meteor which broke up over eastern N. America and (also) subsequently brought the end to the Clovis culture to be more compelling than the theory that it was triggered by the break-up of an ice dam that disrupted the Atlantic circulations. But what so I know?
Andre

Thanks for your valuable reflections, HPD

Not too much to add to that. I wished that average course of events of paradigm shifts was that civilized and easy.

About the temperatures of the Younger Dryas, I hope Nilequeen won't mind if I pass on a little anecdote that she encountered, while she was doing interviews for possible PhD projects. So, while she was having this conversation with somebody, whose name returns several time in that reference list in my previous post, she remarked that, "for instance, we also think that the Younger Dryas was not that cold at all."

The reply bewildered her a few moments when the other said: "We think so too." Unfortunately, no other positive effects emerged from than encounter. Apparently, "We do not rock boats" (quote from "Yes, Minister"). Well, sometimes, that little kid will show up to exclaim that the emperor wears no clothes

Anyway, back on thread, the conclusion that we cannot infer northern hemisphere temperatures from isotope paleothermometers is only getting us halfway. I'm very hesitant to carry it further at the moment. Falsifying theories should be sufficient and one should resist formulating alternative ideas. It's a common fallacy to attack those, call them refuted and conclude from this, that hence, the original theory should be reinstated. Attack, versus defence, is often the superior stragegy. But it is it's probably inevitable because we have not looked into the oceans yet, the source of those water isotopes, be it arid or moist.

Several sediment cores on the ocean floors with a sufficient high resolution, tell the same story as the Greenland isotopes. Hence the question is, what story? It looks that Rosetta's stone was peanuts compared to figuring this out.

Of course there are ideas. I think that would require another thread
NileQueen

Andre wrote:


About the temperatures of the Younger Dryas, I hope Nilequeen won't mind if I pass on a little anecdote that she encountered, while she was doing interviews for possible PhD projects. So, while she was having this conversation with somebody, whose name returns several time in that reference list in my previous post, she remarked that, "for instance, we --think that the Younger Dryas was not so much cold as dry."

The reply bewildered her a few moments when the other said: "We think so too." Unfortunately, no other positive effects emerged from than encounter. Apparently, "We do not rock boats" (quote from "Yes, Minister"). Well, sometimes, that little kid will show up to exclaim that the emperor wears no clothes

I would not agree. You are being far too cynical Andre.
This is not about not rocking boats, but I have not spoken with that professor since then. I probably will be discussing things with him at some point though. I was not bewildered but surprised that someone else was also considering this possibility. Good for him.
Andre

Let's continue with that other ice sheet, of Antarctica, how about the isotopes over there?

We know that the accumulation rate on antarctica is very low, therefore the annual layer counting is much more difficult, only possible in the higher levels. This is the result for the first 5000 years for Vostok and EPICA Dome C, the cores closests to the centre of the East Antarctic Ice sheet.

What you see is detrended relative values in % both for the annual layer accumulation and isotopes. Comparing the anual layer thickness would not work due to the compression.



So the correlation is definitely there. What can we say exactly about the relation with temperature?
Andre

research is continuing to answer that question.

Michel Helsen did his PhD thesis about that question. (large file)

Page 129

Quote:
6.5 Conclusions

Modelling isotope fractionation using both simple distillation models and GCMs equipped with isotope tracers has provided valuable insights in the mechanisms behind observed global isotope variability. In this paper we presented a data set of isotopic composition of Antarctic snow, generated using atmospheric reanalysis data combined with a trajectory model and a simple isotope model. It is demonstrated that this approach is able to reproduce most of the observed spatial gradients, and also qualitatively describes the seasonal cycle. However, isotopic depletion is underestimated for the high Antarctic plateau.

The modelled present-day spatial d18O−T relation in Antarctica appears to vary regionally, which is an indication that this widely used relation is not applicable to all sites and periods.

Our results indicate large spatial variability in the amplitude of the seasonal isotope cycle, mostly in agreement with the observed variability. The underlying mechanisms behind these patterns can be attributed to (1) spatial variations in the seasonal amplitude of condensation temperature and (2) strong seasonal fluctuations in the latitudinal extent of the mean transport path.

Modelled d-excess qualitatively follows the observed spatial pattern, but is generally higher than observations in the Antarctic interior. Analysis of the evolution of d-excess along the trajectories indicates that spatial variations in modelled d-excess are not much influenced by the last phase of transport, but are largely determined by their initial values, which are obtained from the ECHAM4 GCM. The mutual behaviour of d18O and d-excess suggests that parameterisation of kinetic fractionation effects can be improved.

Future work will try to identify to what extent large-scale atmospheric patterns are preserved in the isotopic composition of present-day Antarctic accumulation.


I see a lot of familiar words, like seasonality. And I miss the same words I would have considered important: "dew point" and variation in aridity.

I also see:
Quote:
In Antarctica, snowfall is generally associated with
advection of much warmer air than average
(page 3)

What if the air is warmer but still dry? No snow no temperature. So how accurate is that Antarctica isotope paleo thermometer?
Andre

Okay, gang,

I just received the invitation to write a peer reviewed article on this. Only the size is limited to about half the words I was working on. I think we go for that, ("we" includes Nilequeen, Joanne, who did the bulk of the research) meaning that we will have to reprioritize time. I may do a little less posting.
scpg02

Oooo I'm excited. Good luck.
Andre

scpg02 wrote:
Oooo I'm excited. Good luck.


Thanks, if you care to pre peer-review that would be great.

It occurs to me that the number of hits (743) on this thread is comparatively high, considering this is such a small forum.
scpg02

Andre wrote:
scpg02 wrote:
Oooo I'm excited. Good luck.


Thanks, if you care to pre peer-review that would be great.

It occurs to me that the number of hits (743) on this thread is comparatively high, considering this is such a small forum.


I'll help in anyway I can but doubt I would be of much use. That said I would love to read it as soon as possible.

Knowing what I know about forums, I would guess that each time we come and view a response etc it tacts another view on. They are not unique views in otherwords. Also, given the high traffic on this thread, I'm guessing that the web crawlers are checking this one out which would also tack up views.
Andre

So, I wrote one page of introduction today, new text. This is the first paragraph of the chapter "introduction".

Quote:
The scientific process towards understanding the natural world is a difficult process, constantly facing selective decision making from several alternatives. This choice is logically influenced by the expectations of the researchers according to the current understandings. Especially when the choice holds up when new evidence becomes available, the theory becomes firmer. Nevertheless, the fallacy of the propositional logic may reign here. Cause and effect are not per definition interchangeable. If there is an certain effect, it may not always have the same cause. If it rains the street is wet, but if the street is wet, does it rain? So how does that apply to the techniques of the paleo thermometer. If it is cold the isotopes are down. The isotopes are down, so was it cold?
scpg02

making = made

does it rain = did it rain

So far so good.
Andre

Thanks maggie, but meanwhile we have changed it to

Quote:
The scientific process towards understanding the natural world is a difficult process, constantly having to choose from various alternatives. The choices made, are logically influenced by the expectations of the researchers according to the prevailing views of the time. When the choice holds up when new evidence becomes available, the theory becomes stronger. Nevertheless, the fallacy of the propositional logic may reign here. Cause and effect are not per definition interchangeable. If there is a certain effect, it may not always have the same cause. If it rains, the street is wet, but if the street is wet, does it rain? So how does that apply to the techniques of the paleothermometer. If it is cold, isotopes are down. But if isotopes are down, is it cold?


The first paragraph of an article is the most important and determines how much effort a reader is going to put in it. On the other hand, Most certainly there is no reason for blown up maverick language like scams and so to draw the attention. It is without any doubt that the decision taking processes have been rational at the time; other choices would have seemed irrational. Without the abundance of evidence available now, the researchers basically had little chance to find the correct interpretations. I feel sorry for them. But, that's science, progress by mistakes, eliminating that what we now know for sure what did not happen, will bring us a step closer to the solution of what did happen.
scpg02

does it rain? = did it rain?
Andre

scpg02 wrote:
does it rain? = did it rain?


Did some thinking about that too. But I guess it's stronger in the present tense, exposing the fallacy, since it obviously doesn't have to rain now for the street to be wet. Also my idea was to have the rain/wet sentence and the isotope/cold sentence identical in tense and structure. Sort of rhetoric. But open for discusion.
scpg02

The way it's worded now makes it sound like you are asking if the wet street is going to cause it to rain. It's simply incorrect for your intended meaning.

I interpret your intent as rain causes a wet street but a wet street is not an indication it had rained. A quare is a rectangle but a rectangle is not necessarily a square.

What you have written is:

but if the street is wet, does it rain? which means if the street is wet is it going to rain? Your point is lost. Either that or I misunderstood your intent which is always possible.
Andre

Ok point clear. How about:

If it is raining, the street is wet. The street is wet, but is it raining?

Unfortunately activity forecast for the weekend is somewhat low. I'm shifting locations, decending the mountain to below sea level and having social activities. Joanne is on a big move.
scpg02

Quote:
decending the mountain to below sea level and having social activities.


Sounds like fun and the new phrasing works.
Andre

Noticing that this thread just hit 1000 views. Not bad for a starting little forum.
carnot1824

Is the water isotopes un relieable as the ice core data

Andre, This paper you are working on is very interesting and It seems to be the case the water isotopes used as temperature guides of the past is very flawed and it seems to be the same as the Co2 data from ice cores.
Thanks and keep up the good work
Carnot 1824 Twisted Evil
Andre

Thanks,

Well the publication is basically ready but way too long. I need to talk to the publisher seeing if it is acceptable to have 90% of the references as online supporting material. The references alone take the majority of the text. Razz

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