1

The Environment / What does Iain Stewart's "CO2 experiment" Demonstrate

« on: 05/05/2011 08:07:21 »

Hi Bored chemist, ref. your comment yesterday @ 20:28:44, if you read my comment here of 23rd April @ 20:36:04 you will find an answer in the third paragraph (E-mailed to Professor Stewart and Dr. Hare on 18th April). If the moderator confirms that I am permitted to follow up on that point here then I shall do so but not before.

You may recall your comment here on 21st April @  19:03:23

.. TV science isn't real science- its dummed down for an audience who are not experts in the field ..

As far as climate science is concerned (which is what we are talking about here) I would say that “hyped up” is more appropriate that “dumbed down”.

 Hi Peppercorn,  do you recall your comment on 15th April @ 17:32:52

Why do you think you should 'bring it over'? Unless it's a completely separate question (which it appears not to be) it should stay in the original thread.  Reiterating is not likely to get an answer any quicker & flies in the face of the site's AUP. I think you can expect to find the two merged quite quickly unless you can justify your need to start a new thread on the same subject

If I had not opened this thread at that time these hot topic” exchanges would almost certainly not be taking place due to action by moderator yor_on.

I also tried to start discussing the manner in which climate science is presented through the media to the general public by prominent scientists and the impact that this was having on the credibility of scientists generally. I focussed initially on The Naked Scientists and for my pains was told by moderator JP on 22nd April @ 14:25:10

.. in this thread please stick to the question at hand, which is about the youtube video you posted.  I will lock this thread if you keep using it to .. editorialize about other topics..

I'm doing my best to stick to the "rules of engagement".

Best regards, Pete Ridley

2

The Environment / What does Iain Stewart's "CO2 experiment" Demonstrate

« on: 04/05/2011 22:33:07 »

Bored chemist, with all due respect I can’t see how you can be so sure what is perfectly reasonable to ask. Let’s leave it to the thread moderator to declare his ruling, shall we.

Best regards, Pete Ridley

3

The Environment / What does Iain Stewart's "CO2 experiment" Demonstrate

« on: 04/05/2011 21:59:45 »

Hi Geezer, sorry if I misunderstood your “I really don't know what motivated Stewart to screen the demonstration”. I took that as you raising (i.e. bringing up) the question. I don’t recall anyone else mentioning it but may have missed it.

Best regards, Pete Ridley

4

The Environment / What does Iain Stewart's "CO2 experiment" Demonstrate

« on: 04/05/2011 21:09:13 »

Hi JP, thanks for the speedy response on that question of Geezer’s

.. what motivated Stewart to screen the demonstration ..

I hope that there will be no objection to me raising it as a separate but relate question, which should cover Geezer’s point in his comment today at 19:58:20.

Regarding your

I believe the one thing that remains contentious point is if if the presenter's claim that:

I can show you how carbon dioxide affects earth’s climate

is adequately explained by the experiment

do I take that to mean that you agree with my other two points:

No, the camera picks up only a very small part of the flame’s emissions

and

No, it is the filter that is trapping most of the candle’s heat, not the CO2, so that is why the most of the flame’s emissions don’t reach the camera.

?

The question

Pete, How would you demonstrate to a lay audience that CO2 absorbs IR?

is also off-topic so if that and Geezer’s questions can only be raised as separate ones this gets very messy. After all, one question always leads to another related one. Never mind, forum moderators appear to set their own rules here so we visitors have to abide by them.

Is there a mechanism for linking questions other than verbose explanations about their relationship, or is that classed as off-topic and require that a separate question be submitted for that too?

Best regards, Pete Ridley

5

The Environment / What does Iain Stewart's "CO2 experiment" Demonstrate

« on: 04/05/2011 19:42:14 »

It looks as though I’m going to have to go back to square one here, but tackle this question from another angle. Let’s first look at what Professor Stewart claimed that his demonstration (

would show, quoting those words of his that in my opinion will mislead any of the target audience who have no understanding of how the demonstration is set up or how much of the IR from a heat source such as a candle, the sun or even the earth CO2 absorbs.

0 to 19 secs –

I can show you how carbon dioxide affects earth’s climate using this heat sensitive infrared camera .. a candle, this glass tube .. this canister of carbon dioxide gas ..

but does it do anything of the sort? No, showing that a candle flame changes from white to blue when viewed through CO2 and a 4 µm filter using an IR camera shows nothing whatever about CO2’s effect on the earth’s climate.

22 to 28 SEC. - 

.. the camera picks up the flame perfectly. The hot spots are glowing white ..

but does it do that? No, the camera picks up only a very small part of the flame’s emissions.

30 to 108 secs. –

.. When I turn on the carbon dioxide .. the carbon dioxide in the tube is effectively trapping the heat. The candle’s warmth no longer reaches the camera. Instead it is absorbed by the carbon dioxide inside the tube ..

but is that correct? No, it is the filter that is trapping most of the candle’s heat, not the CO2, so that is why the most of the flame’s emissions don’t reach the camera.

The question raised by that demonstration is the one that Geezer couldn’t answer

.. what motivated Stewart to screen the demonstration ..

I’m interested in that question too and trust that it is acceptable to the thread moderator to try to answer it here. If there is no objection to this then I’ll do a follow-up comment using some interesting stuff I found.

Best regards, Pete Ridley

6

The Environment / Is soot a more immediate threat than carbon dioxide?

« on: 03/05/2011 23:09:28 »

You may be interested in these comments from “Mitigating climate change through reductions in greenhouse gas emissions: climate science constraints on annual global emissions targets for 2020 and 2050:”

.. Different types of aerosols have different effects (e.g. sulphate aerosols are cooling, while black carbon has a warming effect), but the net effect is through to be negative) .. The effects of aerosols on climate are important, but are one of the largest sources of uncertainty in current climate projections ..

Considering the high level of uncertainty in current climate projections arising from the poor understanding of the processes and drivers of the different global climates it is no wonder that it is hard to find any definitive peer-reviewed papers on the significance of black carbon.

Best regards, Pete Ridley

7

The Environment / What does Iain Stewart's "CO2 experiment" Demonstrate

« on: 03/05/2011 22:02:22 »

Hi JP, thanks for giving me the opportunity to re-submit this comment, which I’ve modified as I think that you required.

Hi Bored chemist, what objection did you have to the “Absorption Spectra for Major Natural Greenhouse Gases in the Earth’s Atmosphere” (http://www.iitap.iastate.edu/gccourse/forcing/images/image7.gif) plots which I provided a link to on 23rd April @ 20:36:04? Those plots appear to me to be more revealing than the one you linked to in your comment yesterday @ 10:50:45 because they show clearly that CO2 plays a minor roll compared with other greenhouse gases as far as absorbing IR is concerned.

That demonstration of Professor Stewart was set up specifically to give an exaggerated impression of the extent to which CO2 absorbs IR. That cannot be denied because the set-up designer, Dr, Jonathan Hare, has admitted it

.. The thermal imaging camera we used was sensitive from ca. 1 to 5 µm, quite a large part of the IR spectrum. A lit candle or match produces lots of energy through the IR to the visible. Consequently a candle looks very bright (colourful) on the false colour IR camera image. .. You would think from what I said above that when you view the candle through the tube using the camera, and you introduce CO2 the bright flame would 'disappear' due to the IR absorption. However, when you try this it doesn't work, the candle doesn't disappear! The reason is that the CO2 absorptions observable by the IR camera are quite weak and are only in a relatively small part of the spectrum. The only way to get the demonstration to work is to have a 'CO2 filter' on the camera. This only lets through IR at around 4 µm, close to one of the CO2 absorption's (which are broadened a bit at atmospheric pressure). The filter blocks out much of the IR energy so that the CO2 absorption is not so swamped anymore and this allows us to now observe our vanishing candle effect ..

I have already pointed this out to all of the viewers of this thread, on 23rd April and it seems obvious to me, as a sceptic of the CACC doctrine, that  the intention was to mislead the viewers about the extent of IR absorption by CO2 in order to support the claim that our continuing use of fossil fuels is leading to CACC.

As I mentioned here in my opening comment and also to Professor Stewart and Dr. Hare in my E-mail of 18th April

.. I do not challenge the fact that CO2 absorbs rather a small part of the IR band compared with the other greenhouse gases, particularly H2O but I puzzled over the manner in which Professor Stewart chose to demonstrate it. In the introduction before describing the apparatus Professor Stewart says “I can show you how carbon dioxide affects the earth’s climate using this .. ”. The demonstration does not show what is claimed, because CO2 is only opaque to a small portion of the IR band, as clearly shown in “Absorption Spectra .. ” (http://www.iitap.iastate.edu/gccourse/forcing/images/image7.gif). The set-up and explanation of what is happening gives the false impression that a significant amount of IR from the candle is absorbed whereas in fact CO2 only absorbs a small proportion of the IR. ..

There’s more in that Email if you want it. BTW, I still haven’t had a response from either Professor Stewart of Dr. Hare.

Best regards, Pete Ridley

8

The Environment / What does Iain Stewart's "CO2 experiment" Demonstrate

« on: 02/05/2011 10:28:23 »

Hi yor_on, , unlike many bloggers and moderators I wouldn’t want to hide behind any false name because people can get led astray by them. If I hid behind Mr Hammer someone might mistake me for Frederick Phillip (http://extras.journalnow.com/hammer/pdfs/warrants_ashe1.pdf) and that would be so misleading. I’m happy to stick (ferret) in between Pete and Ridley and I was nicknamed “fish” at school, but that’s another story having nothing to do with the question at the top of this thread.

Mind you, it seems that all of a sudden the “rules of engagement” on this thread have suddenly been relaxed. One of the moderators said to me on this thread on 22nd April @ 14:25:10

.. in this thread please stick to the question at hand, which is about the youtube video you posted.  I will lock this thread if you keep using it to .. editorialize about other topics.  We've been fairly lenient in allowing you to freely post content so far, but this is primarily a science Q&A site, not your personal blog ..

It seems to me (and I’m sure to other viewers of this thread also) that you have been allowed to “editorialise about other topics” and use this as your “personal blog” with impunity. In one day yesterday you were permitted to submit about 4500 words which were absolutely nothing to do with

the youtube video (I) posted”

It appears that there is one rule for the general public and another for someone who

.. is a valued member of the community and .. a moderator on this forum

It is evident from your essay and from other contributions of yours that you are a staunch supporter of the doctrine that our continuing use of fossil fuels is leading to Catastrophic Anthropogenic Climate Change (CACC). Is that one of the qualities required by The Naked Scientists to be accepted as

a valued member of the community and .. a moderator on this forum

? Or, as BenV put it on 22nd April @ 16:20:22 about another TNS blog/forum moderator

.. JP was invited to become a moderator as he was a valued member of the site. .. - they have earned their privileges ..

I Googled - "The Naked Scientists" yor_on "climate change" “global warming” – and found more yor_on comments all demonstrating your faith in CACC. One excellent example, which also suggests that you have the full support of The Naked Scientists, was your comment featured in Science News The Naked Scientists: Science Radio & Science Podcasts “A breath of fresh air in climate change debate” thread (http://www.thenakedscientists.com/HTML/content/news/news/2052/) and appeared again in the “Can we reduce climate change with our infrastructure?” thread (http://www.thenakedscientists.com/forum/index.php?topic=33987.0). The thread originator, thedoc (another of those “false names” who gives nothing away about his/her specialist scientific discipline) must have been dissapointed that after waiting for almost 2 weeks for anyone to make a comment the only person showing any interest was one of The Naked Scientists own moderators.

I must dash now as she who must be obeyed is calling but I hope to return later today.

Best regards, Pete (ferret) Ridley

9

The Environment / What does Iain Stewart's "CO2 experiment" Demonstrate

« on: 01/05/2011 23:22:58 »

Hi Yor_on I’m sure that you astounded more that just me with that load of rambling nonsense which is about as far off-question as you could be (and still no objection from the moderator if this blog).

I think that Arthur Ducette was spot on when he said of you on 22nd Sept 2007 @ 13:14 “ .. Your posts, for the most part, are good examples of media/scientists distorting the message to make a political oriented point” (http://www.physforum.com/index.php?s=24dfd9c137656d85aa00f620e59f58d1&showtopic=16294&st=15) and

.. you obviously don't recognize MARKETING spin when you read it. You apparently can't TELL that there are a LOT of people trying to SELL you an idea. You seem to EASILY fall for their MARKETING SPIN. Worse, you then try to SELL others on your RELIGION. Oh well, It worked for the Missionaries. Arthur ..

I do fully agree with one thing that you have said on 23rd Sept. 2007 @ 12@51

.. It's no big deal, neither you nor me are going to make a difference here Mother nature will take care of it all, little caring for what we might think. And no ranting, from any corner, will make it different ..

You’re quite right, the CACC doctrine is no big deal and none of us will make a difference. It is Mother nature who has control over the different global climates, not humans. As for the ranting making no difference, why do you persist in doing it then?

Best regards, Pete Ridley

10

The Environment / "Another Hockey Stick Illusion"?

« on: 01/05/2011 21:44:01 »

In response to my original question Professor Wolff has provide two excellent overviews of the fundamental issue of how valid are the attempts to reconstruct past atmospheric composition from air recovered from ice sheets. I thank him for making the time to put together those submissions and hope eventually to cover all questions about the validity of those reconstructions. It is sensible to tackle in a structured manner all of the different complex processes that distort the composition of the original atmospheric air, To this end I have asked the founder of this blog/forum, Chris Smith, if it is possible to expand the thread question to read “Another Hockey Stick Illusion?” – “Do glaciers tell a true atmospheric CO2 story?”. That then allows us to follow the relevant processes from the top of the ice sheet down to the depths of the ice beneath.

I first would like to focus on the matter covered in my original question, which is

.. why do paleo-climatologists use collision diameter in preference to kinetic diameter when considering the migration of air molecules through firn and ice? ..

I shouldn’t have to keep repeating this but there are several people who have commented here who seem not to have read it properly. Professor Wolff went to a great deal of trouble to explain his understanding of it in his very first comment here (27th April @ 14:53:30) and I can’t improve on that.

Once a convincing answer has been given to my original question I would like to return to those other important points made by Professor Wolff that do not directly address my original question but are relevant to “Do glaciers tell a true atmospheric CO2 story?”.

In that comment Professor Wolff said

.. The underlying issue is whether we can believe that the air in bubbles in ice cores is an un-fractionated representation of the atmosphere .. when we crack open a bubble of air, does it contain exactly the relative proportions of different molecules as the air in the atmosphere ..

Note that reference to “air”, , not N2, not O2, not Ar, not CO2, etc. etc. etc. but “air” – all of it.

He then went on to say

.. you are more concerned about whether there is a further fractionation at the final stages of enclosure, related to the size of the molecule – do some smaller molecules more easily escape enclosure leading to a fractionation? ..

Note this time that Professor Wolff focuses on “the final stages of enclosure”, i.e. the deep firn, which is precisely where my original question is targeted at.

Professor Wolff then said

.. Certainly such a fractionation can exist for some atoms and molecules: it is very strong for neon (Ne), noticeable for O2 and Ar (at the permil to 1 percent level) but the literature says that there is no fractionation for CO2 (or CH4) compared to N2 ..

The issue in question should by that stage have been reasonably clear to anyone following this thread.

Let’s look now at what “the literature says” about size-dependent fractionation in deep firn as it approaches close-off, using three papers that Professor Wolff made reference to. First let’s see what is said in the 1996 paper “Natural and anthropogenic changes in atmospheric CO2 over the last 1000 years from air in Antarctic ice and firn” by Etheridge et el. As I pointed out almost a year ago elsewhere, that paper (and as far as I could find then, no other that Etheridge was involved in) made any reference to size-dependent fractionation of air in the deep firn, the only references to fractionation being to the gravitational type. I propose to return to this paper at the appropriate point in the wider discussion about “Do glaciers tell a true atmospheric CO2 story?”.

The papers that are much more relevant to my original question are the two from 2006 that Professor Wolff makes reference to. First let’s look at what “Evidence for molecular size dependent gas fractionation in firn air derived from noble gases, oxygen, and nitrogen measurements” by Huber, Severinghaus, et al. (http://icebubbles.ucsd.edu/Publications/Huber_closeoff_EPSL2006.pdf) says about this. I make the assumption that all eight co-authors can reasonably be called paleoclimatologists. The next point to clear up is whether or not their paper is about the migration of air molecules through firn and ice. The title of the paper certainly suggests so, the paper discusses the molecules of all of the different atmospheric air components and their diffusion within the ice sheet and most importantly

.. In the present study, however, we are mainly interested at the bottom of the firn air column ..

This is precisely the area on which I am focussing, as Professor Wolff acknowledged when saying in his first comment here

.. you are more concerned about whether there is a further fractionation at the final stages of enclosure, related to the size of the molecule – do some smaller molecules more easily escape enclosure leading to a fractionation? ..

At the bottom of the firn air column, as close-off is approached, pores on the surface of the closing air bubbles and the channels that link air pockets must at some stage approach molecular size, i.e. the firn becomes a nanoporous medium. Gas purification experts use nanoporous media (e.g. zeolites) in industrial applications and numerous papers and patents can be found that describe the process. All of these refer to molecular kinetic diameter, not collision diameter, e.g. see the 2002 paper “Application of natural zeolites in the purification and separation of gases” by Ackley et al. (http://www.zeolitanatural.com/docs/gasseparation2.pdf) and  “Sol-Gel Processing of Inorganic Membranes for Natural Gas Purification” (http://www.netl.doe.gov/kmd/cds/disk28/NG8-3.PDF) which says

.. To efficiently separate CO2 (kinetic diameter = 0.33 nm) from CH4 (kinetic diameter = 0.38 nm) or (harder still) N2 (kinetic diameter = 0.364 nm) from methane, it is necessary to accurately control the average pore size between about 0.3 and 0.4 nm and achieve a narrow pore size distribution ..

So, I repeat my original question

.. why do paleo-climatologists use collision diameter in preference to kinetic diameter when considering the migration of air molecules through firn and ice? ..

As I discussed over a month ago on the Climate Conversation Group’s “Fallen snow” thread (which I provided a link to in my first post on this thread)

.. Huber et al. .. say “ .. a critical size of 3.6 Ĺ implies diffusion through channels of about the same dimension .. an outlet from a closing bubble .. changes its dimension steadily from open to closed. .. Diffusion coefficients of gases in ice show a size dependence similar to our findings beside for Ar and O2 .. ”. They should have included CO2 along with those two but didn’t because (I believe) they were focussing on the close-off fractionation of other gases and were misled into ignoring CO2 through using collision not kinetic diameter ..

I won’t say much here at this stage about the paper “Fractionation of gases in polar ice during bubble close-off: New constraints from firn air Ne, Kr and Xe observations” by Severinghaus & Battle (http://icebubbles.ucsd.edu/Publications/closeoff_EPSL.pdf). In Section 1.2 and 3.1 of the paper they provide a good description of the process that I am focussing on and they discuss the results of their

.. simple model of the bubble close-off fractionation …

They go on to say

.. The model presumes that fractionation is caused by selective permeation of gas through the ice lattice from slightly overpressured bubbles. ..

I’m puzzled by that reference to “ice lattice” because there is another process that is thought to take place after close-off. This is a process related to the one that I am focussing on at present and I would like to consider this one later, however, it is noticeable that they again refer to the 0.36nm molecular size. They say

.. The large atoms Kr and Xe do not appear to be fractionated by this process, despite the large size difference between the two gases, suggesting a threshold atomic diameter of 3.6Ĺ above which the probability becomes very small that the gas will escape from the bubble. These findings have implications for ice core and firn air studies that use gas ratios to infer paleotemperature, chronology and past atmospheric composition ..

Once again, they ignore kinetic diameter in favour of collision diameter (see Table 1).

If anyone is interested, more comments of mine on this paper can be found on the Climate Conversation blog threads:
- “It’s not warming, you nitwit — it’s cooling” (http://www.climateconversation.wordshine.co.nz/2011/03/its-not-warming-you-nitwit-its-cooling/) in my comment of 21st March @ 11:26 and
- “Fallen snow” (http://www.climateconversation.wordshine.co.nz/2011/03/fallen-snow/) in my comment of 23rd March @ 11:17.

Professor Wolff, are you at liberty to attach a copy of your 2011 paper “Greenhouse gases in the Earth system: a palaeoclimate perspective” so that subsequently we can look at the evidence provided therein supporting your conviction that

.. the ice-core record provides a faithful record of changing atmospheric composition. ..

(http://www.ncbi.nlm.nih.gov/pubmed/21502180)? That paper may provide the answer to the question used by Professor Jaworowski et al. as the title to their 1992 paper “Do glaciers tell a true atmospheric CO2 story?” (http://www.co2web.info/stoten92.pdf).

I referred to that paper in my comment of 13th April @ 21:58:19) and as I said then

.. When I discussed this last June with Professor Zbiniew Jaworowski, whose 1992 paper first drew my attention to this issue, he expressed the opinion that “This is a highly specialized field of science. My impression is that it is a terra incognita for glaciologists”. Subsequently I have asked the same question of Professors Richard Alley, Jeffey Severinghaus and Michael Bender without receiving any worthwhile justification for their use of collision diameter. ..

Best regards, Pete Ridley

11

The Environment / What does Iain Stewart's "CO2 experiment" Demonstrate

« on: 01/05/2011 09:14:13 »

Hi Yor_on I am astounded that you have been allowed to contribute three long-winded commentaries about the general greenhouse theory without the thread moderator screaming “off-question”. Have you read the original question that I raised here? It’s specifically about Professor Stewart’s demonstration, not about the “greenhouse” theory.

As I told you yesterday, I complained to Chris Smith about there being declared rules for the general public and none for the moderators and that one of those requirements for moderators should be impartial.

Best regards, Pete Ridley

12

The Environment / "Another Hockey Stick Illusion"?

« on: 30/04/2011 20:51:06 »

Hi Yor_on, I consider that The Naked Scientists blog/forum is an excellent place to have this issue discussed. The viewing figures tell me that this thread is attracting a lot of attention but maybe you interpret those figures in a different way to what I do. I repeat, my question has not yet been answered so let’s wait for further help from those who have specialist knowledge in the subject. I believe that the only person to contribute to this thread so far who fits that category is Professor Wolff. Hopefully he will continue to give his valued assistance and others with such expertise will join in.

Hi Bored chemist, from your contributions so far am I being fair if I suggest that you do not have the necessary expertise in the subject to state that

.. it has been answered ..

You are mistaken if you  have the impression that I

.. have missed something ..

I certainly don’t miss anything that Professor Wolff says and have every intention of following up on all of it. In the mean time I hope that Professor Severinghaus or Dr. Huber will join in because it was they who modelled the process so should be able to give a  satisfactory answer to my original question. It is possible that Professor Wolff will return to it too and others may join in.

Best regards, Pete Ridley

13

The Environment / "Another Hockey Stick Illusion"?

« on: 30/04/2011 11:51:45 »

Hi Yor_on, I do not agree with your

.. You've got your answers ..

Here is my opening question again

.. why do paleo-climatologists use collision diameter in preference to kinetic diameter when considering the migration of air molecules through firn and ice? ..

Only one person, Professor Eric Wolff, has tried to respond properly to that question (see 27the April @ 14:53:30 and 28th April @ 08:45:37). He is not one of The Naked Scientists but works with the British Antarctic Survey and is recognised as a specialist in the area relating to part of my question. He has shown that he fully understands my question but even he has not answered it. Others here may think that he has but by reading his penultimate paragraph in his response of 27the April @ 14:53:30 carefully enough and having done whatever background reading is needed to understand it and my original question, it will be realised that the specific question remains unanswered. Proferssor Wolff focussed on CO2 but my question is not specifically about CO2. It refers to “air molecules”, which covers not only CO2 but N2, O2, Ar, CH4, He, Ne, etc.

I expect that Professor Wolff would quite readily accept what I have just said. More exchanges are needed before the question is answered and that is one reason why, after receiving Professor Wolff’s response, I E-mailed specialists like Professor Jeff Severinghaus to take a look at this thread. Professor Severinghaus and his associate Dr. Chris Huber have written papers on this specific issue of size-dependent fractionation of “air molecules” but used collision diameter not kinetic diameter and did not specifically investigate CO2. The reason appears to be because their model led them to conclude that molecules having a diameter larger than 0.36nm are not affected by the size-dependent fractionation process. CO2 has a collision diameter of 0.39nm but a kinetic diameter of 0.33nm.

If they had used the kinetic diameter measure of molecular size then I hypothesise that their conclusion s about CO2 would have been different. As I have said already, expert practitioners in gas purification through nanoporous media do not use collision diameter in their analyses, they use kinetic diameter. That is what gave rise to my still unanswered question.

Professor Wolff acknowledged

.. I agree that one could imagine constructing a model in which the kinetic diameter is important (and because of it's non-spherical nature, CO2 has a smaller kinetic than collision diameter).  However, in such a model, Ar would be more fractionated than O2, whereas Severinghaus et al's data shows it is only one-third as fractionated; and as you are implying, CO2 would be somewhat more fractionated than either Ar or CO2 ..

(I think that last should be O2). I expect that gas purification specialists had been involved and the research done by Severinghaus and Huber kinetic diameter would have been used in the model.

As Professor Wolff said in his second response on 28th April @ 08:45:37 

.. I understand your point that, if the process was just physical permeation through a small gap, then we would expect the kinetic diameter to be relevant.  But the data are not consistent with that, so the molecular level process must be somewhat different to that.  What Severinghaus and others note is that there seems to be no fractionation for molecules with a collision diameter more than 3.6 Angstroms ..

Following several E-mail exchanges with Professor Severinghaus I asked on 29th December about the structure of the models that he had used, including

.. I note that in both papers you have used collision diameter and ignored kinetic diameter, but why?. Have you carried out any research using kinetic diameter instead? If not do you have a feel for what differences this would make? ..

For some reason I didn’t get a response.

The validity of the attempts to reconstruct past atmospheric composition from air recovered from ice is fundamental to the CACC hypothesis. Many questions about this have been raised repeatedly since at least 1992 by others such as Professor Zbiniew Jaworowski and Professor Hartmut Frank. The question that I posted here initially is just the first of a long string of such questions.

Contrary to what has been suggested here, that first question of mine remains unanswered, hence, in my opinion this very popular “Hot Topic” thread, which continues to attract significant views, should remain open.

Best regards, Pete Ridley

14

The Environment / "Another Hockey Stick Illusion"?

« on: 29/04/2011 17:49:42 »

Hi Imatfaal, I’m at risk of upsetting the moderator of this blog by responding to your off-question comment, but I’ll risk it with a “quickie”.

Just what is a blog, anyway? Defining this variable form is not easy in the highly opinionated blogosphere ..

(http://www.ojr.org/ojr/stories/050929/) – but at least I’ve learned what an agora is.

Now, what have you to say about collision v kinetic diameter in the close-off zone of deep firn?

Best regards, Pete Ridley

15

The Environment / What does Iain Stewart's "CO2 experiment" Demonstrate

« on: 29/04/2011 09:03:43 »

Hi Geezer, although this is “off-question” and may upset the moderator, it takes courage to admit when you are wrong so congratulations.

The reason that I mentioned in my TNS profile that I was involved in EMC was so that anyone so inclined could Google me and not get confused by all of the other Pete Ridley’s around the world. Another blogger elsewhere thinks that I’m running a recycling company.

Now, have you anything else to add about that demonstration of Professor Stewart’s (or any of his other BBC presentations)?

Best regards, Pete Ridley

16

The Environment / "Another Hockey Stick Illusion"?

« on: 28/04/2011 20:54:48 »

I see that I managed to attach that pdf without realising I’d done it. What a great blog this is.

17

The Environment / "Another Hockey Stick Illusion"?

« on: 28/04/2011 20:50:10 »

Hi Bored chemist, although you may have lost interest in discussing this size-dependent fractionation issue and want to

.. stop now, and go out to play ..

you did raise a relevant question on the “What does Iain Stewart's "CO2 experiment" Demonstrate” thread in your comment of 22nd April @ 17:35:55. Rather than your question being followed up there, which is on a separate topic altogether, maybe it should be addressed here or, better still, as a new question related to the validity of the attempts to reconstruct past atmospheric CO2 content from air in ice sheets.

In response to my

.. I am surprised that you have had nothing scientific to contribute to the question of how the individual molecules of the different atmospheric gases react within nanoporous media like firn ..

you said

.. Did it occur to you that the fact that no chemical reaction takes place might have some importance there .. Actually I'm an analytical chemist but, as I have pointed out, what you are asking about is physics

.

Perhaps, as an analytical chemist, you can help clear up other significant uncertainties regarding those other air fractionation processes that take place right from the beginning of the process of ice-sheet development. After all, the validity of those attempts to reconstruct past atmosheric CO2 content from air “trapped” in ice is rather fundamental to the argument presented by the IPCC and its supporters.

Let’s start with the very first part of the ice sheet development process, the falling snow. In my list of scientists I mentioned Professor Hartmut Frank, Chair of Environmental Chemistry & Ecotoxicology, University of Bayreuth. Professor Frank wrote a forward to Jaworowski’s 1994 paper “Ancient Atmosphere – Validity of Ice Records” (http://www.springerlink.com/content/284n23943h8g687p/fulltext.pdf?page=1). Professor Frank sent me a slide from one of his presentations last year to graduates at Technical University in Gdansk. [ Invalid Attachment ]

He described it  as “ .. a simplified illustration of the major processes which are leading to changes of gas concentrations in the secondary bubbles (including and especially of carbon dioxide) .. ”. I don’t know how to embed a pdf page into this comment so will have to describe it (if anyone would like a copy then send me a “Personal Message” and I’ll E-mail it).

The slide provides a diagram showing falling snow beneath which is the section of a fully developed ice sheet. It discusses the manner in which atmospheric air collected within the voids of forming snow has already been depleted in CO2 before it even hits the top of the ice sheet. Alongside it says “Assuming a specific weight of 1 dm3 snow as 0.1 kg/L, it consists of 10 Vol-% of snow-ice and 90 Vol-% of air. Thus, a dm3 snow may contain a total carbon dioxide content of which 4 mg is adsorbed and 0.54 mg comes from the air between the snow flakes –explaining the high values found in ice cores by the gas extraction over long time in the molten state”.

It then goes on to summarise the snow/firn/ice compaction stages after “Deposition:
- Compaction to firn, air bubble closure (when?),
- Chlathrate formation (CO2~ 5 atm) [CO2•5 H2O] preferred diffusion of CO2 into the ice matrix
- Chlathrate formation (N2, O2at ~ 20 atm)
- Carbonic acid formation (formulae shown) N2, O2 non-reactive: selective depletion of CO2
- Primary bubbles disappear.
- Upon drilling and horizontal storage of ice cores, expansion and back diffusion of N2, O2 and CO2 (and slow decomposition of carbonic acid) into secondary bubbles occurs, at different rates”.

My question to you at this stage is whether or not that initial adsorption of CO2 in the snow is a chemical or a physical process (http://www.tutorvista.com/content/chemistry/chemistry-iv/surface-chemistry/absorption-types.php). My suspicion is that it is Chemisorption but as I’m not a chemist I’d appreciate your opinion. Following on from that is another question about adsorption in the deep firn, but that can be followed up later. Let’s work our way down the ice sheet looking at the different processes that Professor Zbiniew Jaworowski has been expressing concern about since 1992 and return to deep firn adsorption of CO2 and clathrate formation at a later stage.

I can ask Professor Frank and Professor Jaworowski and other scientists (see my comment of 13th April @ 21:58:19 on this thread) if they are interested in helping on those other processes.

Best regards, Pete Ridley
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18

The Environment / "Another Hockey Stick Illusion"?

« on: 28/04/2011 20:34:11 »

Hi Professor Wolff, I think that Geezer’s comment will reflect what many of the silent viewers of this thread will be thinking. I’ll be most surprised if others do not start jumping in with comments. Thanks for another excellent, helpful response which, as far as the main question in this thread is concerned, seems to be covered in Para. 3

.. The data show that there is a fractionation of some atoms/molecules relative to others in this zone, meaning that .. the bubbles are slightly depleted for some "smaller" molecules compared to the air above  ..  People have hypothesised that this effect is controlled by a process where smaller molecules are slightly more likely to escape during the final stages of enclosure, but we frankly do not know the exact mechanism ..

In other words, this type of fractionation is evidenced by the data and could be due to size-dependent fractionation as I have described it but this has not been properly researched and we just do not know. My understanding of the work of Severinghaus and Huber, which is the basis for many other papers on the subject and specifically addresses this type of fractionation, is that they rely upon models which use the wrong measure of molecular size, collision rather than the appropriate measure, kinetic diameter.

Let me leave that for a moment to ask about ice sheet structure. Am I correct in thinking that what you refer to in 2. of your summary as the “diffusion zone” is also called by others the “stagnant zone” or is this what you call in 3. the “non-diffusive zone” or is this zone also referred to as the close-off zone? (pause for breath).

Also, I think that it would be sensible to resolve any uncertainties arising from your first comment here before tackling those in your second. Your structure summary point 3. leads nicely into something that came to mind after I read your E-mailed response of 26th.

In your E-mail you sent me the paper “Natural and anthropogenic changes in atmospheric CO2 over the last 1000 years from air in Antarctic ice and firn” (http://www.agu.org/journals/ABS/1996/95JD03410.shtml) by Etheridge et al. (one of the papers that Dr. Nisbet had also sent me). Then (and on the thread here on 27th) you make reference to Fig. 2 on Page 4120. I’m unable to provide a link to the full paper so for anyone who is interested and can’t get a copy of the paper I’ll try to describe what Fig. 2 shows. Alternatively, the CO2 (and CH4) “data and descriptions” are available free from NOAA (http://www.ncdc.noaa.gov/paleo/icecore/antarctica/law/law_data.html).

Fig. 2 is a graph of CO2 on the Y-axis (origin 310-360ppm) and depth in the ice sheet (origin 0-120m). The plotted points start at 10m, 353ppm with an almost linear fall to 70m, 343ppm. a gradient of 0.17ppm/m. Around 70m there is a turning point to a steeper fall from 70m, 343ppm to 115m, 310ppm,  a gradient of about 0.73ppm/m.

Related to Fig. 2 is Table 2 on Page 4119, which says

.. Depth Where Sealing Occurs - 72m, Age of ice at Sealing Depth – 40years, Mean Age of CO2 in Air at Sealing Depth – 10years, Difference Between Ice Age and Mean Air Age – 30years, Duration of Bubble Close-off Process 8years

The inferences that I draw from Table 2 are:
- ice accumulation rate = 72m/40years = 1.8m’year, but this conflicts with the statement in “Interactive comment on “Post-coring entrapment of modern air in polar ice cores collected near the firn-ice transition: evidence from CFC-12 measurements in Antarctic firn air and shallow ice cores” by M. Aydin et al. 30 March 2010” (http://www.atmos-chem-phys-discuss.net/10/C1119/2010/acpd-10-C1119-2010-print.pdf) that

.. The accumulation rate at their study site was about .. 1.2 m/y (ice equivalent) .

(any suggestions?)
- the close-off process is very gradual, with fractionation of the smaller molecules taking place over several years (around 10), which I understand to be the period in Fig. 2 during which the CO2/depth gradient of 0.17ppm/m in the firn (the diffusion zone?) is gradually changing (in the non-diffusive zone?) to a gradient of 0.73ppm/m (in the “solid” ice – I use parentheses because of the persistent movement of molecules within that zone due perhaps to H-bond breaking and fractures, another aspect of the fractionation process to be considered later).

The first thing that struck me as odd when I first saw Fig. 2 in 2008 was the discontinuity occurring around 70m. At that time I had come across a related graph (http://maps.grida.no/library/files/historical-trends-in-carbon-dioxide-concentrations-and-temperature-on-a-geological-and-recent-time-scale.jpg) on the site of Norwegian GRID-Arendal, a collaborating centre of the United Nations Environment Programme (UNEP). More recently I found the US EPA’s page “Atmospheric Concentrations of Greenhouse Gases” which presents a graph superimposing data from 6 Antarctic ice cores, spliced with measurements from Mauna Loa and sundry other SH and NH locations (http://cfpub.epa.gov/eroe/index.cfm?fuseaction=detail.viewInd&lv=list.listByAlpha&r=231323&subtop=342). That too displays a puzzling discontinuity for CO2 concentration, but in that case relating to the difference between the “normal” periodic swings between ice ages and interglacials).

Rather than jump to the conclusion that the apparent increase in mean global atmospheric CO2 was a consequence of the industrial revolution and our increasing emissions of CO2 into the atmosphere (not least from using fossil fuels) I considered it worthwhile trying to identify another reason for that discontinuity seen in ice core data from numerous different locations. I was reminded of the concerns expressed by Professor Zbinew Jaworowski about fractionation in the ice (see my opening post on this thread) and that led me to research this issue of size-dependent fractionation in the deep firn.

The inferences that I drew from Fig. 2 of the Etheridge paper were:
- CO2 experiences significant size-dependent fractionation down the pressure gradient towards the surface at depths around the nominal close-off depth of 72m where the larger gas molecules (N2, O2, Ar, CH4, Kr, Xe) are trapped in the air bubbles,
- above the nominal close-off zone CO2 is no longer experiencing size-dependent fractionation but is being mixed by diffusion with younger air within the firn.
 
You said that

.. In their figure 2, they (Etheridge et al.) show samples they have measured in the firn air .. and in trapped bubbles at the same depth .. : they conclude that the difference is a random 1.3 ppmv, showing that the enclosure process does not affect the concentration.  This is a really direct and elegant measurement which shows that, at least at Law Dome, there is no fractionation of CO2 on enclosure

. I need to look more closely at that and revert. Meanwhile I propose to E-mail the scientists I have been exchanging E-mails with for the past year to see if any of them wish to get involved here. After all, opinions from other specialists, especially some who have the necessary expertise in the movement of different molecules in sub-nano-porous media (such as from those involved in gas purification for the energy industry, e.g. removal of of impurities from mine gas to bring it up to grid standard) could help to remove some of the uncertainties arising from the fact that

.. we frankly do not know the exact mechanism ..

.

If anyone viewing this thread who has such expertise or knows specialists who have it then I’d appreciate them inviting their involvement.

BTW, for anyone who was/is interested in taking a look at those links to ice sheet structure that I provided at the end of my comment yesterday @ 22:39:34, Dr. Al Rango, the main author of “Snow crystal imaging using scanning electron microscopy: III. Glacier ice, snow and biota” (http://itia.ntua.gr/hsj/45/hysj_45_03_0357.pdf) has expressed an interest in joining the discussion. Dr. Rango has kindly offered to try to get his hands on more of those excellent images and the data used as the basis for that paper. I again recommend a look at those images.

Best regards, Pete Ridley
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19

The Environment / What does Iain Stewart's "CO2 experiment" Demonstrate

« on: 28/04/2011 16:54:42 »

Hi Bored_chemist, the point that I’ve been trying to discuss here is not how significant or otherwise H2O is in relation to other greenhouse gasses but how the demonstration by Professor Stewart was in my humble opinion designed and presented in such a way that it gave a distorted picture to its audience of how significant CO2 is as a greenhouse gas.

You say

.. it has nothing to do with the question of whether or not adding CO2 to the air (which we have done) will also add net warming to the climate (which we have observed) ..

I have no disagreement that we add CO2 to the atmosphere through burning fossil fuels and in other ways (like breathing [prop] [:0]) or that there has been a welcome amount of warming since the Little Ice Age, but that topic is “off-question” so may be frowned upon by the thread moderator.

Best regards, Pete Ridley

20

The Environment / "Another Hockey Stick Illusion"?

« on: 27/04/2011 22:39:34 »

Hi Professor Wolff, thanks for responding so promptly to my Email of 20th with your detailed explanation. This is just the sort of response that I have been trying to elicit for over a year now. You have given me plenty to think about and I was in the middle of replying to your E-mail of yesterday when I spotted that this thread had been unlocked (thanks moderators) and you had posted here. Your explanation here is very similar to what you E-mailed, apart from the background information that you have provided for those who aren’t so familiar with the issue. I’m sure they’ll appreciate it.

I have several points that I’d like to discuss and will do so one post at a time until you get tired of responding. I had thought of simply exchanging E-mails but I’m sure that there are others who are interested in this, judging by the views this thread is getting.

You say

.. Secondly, the air is fully enclosed in ice (ie the ice becomes impermeable) only at a depth, typically 60-100 m depending on the site, and the air is sitting in a slowly diffusing column of firn until it is enclosed (typically taking 1-3 decades to reach the enclosure depth) ..

so maybe I’m misunderstanding the ice sheet structure.

Here’s a diagram that might help  [ Invalid Attachment ]

I was under the impression that from the top down there is:
- a very small depth (much less than 1m?) of snow, which is affected by surface activity such as wind and others, below which there is
- a significant depth (tens of metres) of increasingly dense firn (see Figs. 2 & 3 of the Goodwin reference below) in which all air components diffuse relatively freely (is this also known as the stagnant zone?), below which there is
- a relatively short depth (10m?) in which the pores and channels interconnecting air pockets gradually reduce to nanometric size, where free diffusion no longer takes place and size-dependent fractionation occurs (is this known as the transition zone?) below which
- all air pockets are sealed to molecular movement other than through the crystal lattice via the breaking of hydrogen bonds.

Consequently, I find your

.. the air is sitting in a slowly diffusing column of firn until it is enclosed ..

surprising, because I would expect that the air components having the largest molecular size (e.g. CH4, N2, O2, Ar) would be “enclosed” before the smaller molecules like CO2, Ne and He, which will continue to leave the air pockets and move down the pressure gradient towards the surface.

Can we concentrate on that first. Are you saying that this does not happen?

For anyone who is interested, one description of the typical ice sheet structure is given in “Snow-accumulation variability from seasonal surface observations and firn-core stratigraphy, eastern Wilkes Land, Antarctica” by Ian D. Goodwin in 1991 (http://www.igsoc.org/journal/37/127/igs_journal_vol37_issue127_pg383-387.pdf). Another paper “Polar ice structure and the integrity of ice-core paleoclimate records” by Faria et al. in 2009 (http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6VBC-4XT2CSW-1&_user=10&_coverDate=01%2F31%2F2010&_rdoc=1&_fmt=high&_orig=gateway&_origin=gateway&_sort=d&_docanchor=&view=c&_searchStrId=1733120326&_rerunOrigin=google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=a1695e258504733d23512b27bd34e36c&searchtype=a) provides a helpful diagram in

.. Fig. 3. Basic outline of the multi-scale structure of the EPICA-DML ..

plus some excellent images, mostly of deep ice but

.. Fig. 11. Microstructure-mapping mosaic images of two firn sections from 60 m to 85 m depth ..

relates to this discussion.
There are also some excellent SEM images of ice structure in “Snow crystal imaging using scanning electron microscopy: III. Glacier ice, snow and biota” by Rango et al. (http://itia.ntua.gr/hsj/45/hysj_45_03_0357.pdf).

Best regards, Pete Ridley