Jaworowski et al.‘s 1992 article in The Science of the Total Environment

This paper is lengthy (at 57 pages), and lavishly endnoted (with 177 references in the bibliography). In this paper, Jaworowski, Segalstad and Ono present a listing of supposed problems with ice-core gas measurements.
Here’s the title and abstract:
Jaworowski et al. 1992 title & abstract
This paper fails to present any coherent explanation of why ice core measurements in general should be considered unreliable. Instead, Jaworowski and colleagues develop an unconnected list of complaints regarding ice core methodology, without presenting any testable theories as to what the effects of those problems should be. In some cases, e.g. their assertion that the “age assumption” regarding firn consolidation is unproven, they ignore successful research that contradicts their thesis. In other cases, as noted in connection with the history of atmospheric CO2 measurement, they distort the conclusions of other researchers in an apparent attempt to spread a cloud of doubt over the entire enterprise.
Their criticisms of ice core measurements fall into a few broad categories:
(1) Lower CO2 concentrations have been reported by more recent research for similar ice deposits.
(2) Horizontal, impermeable barriers in snow and firn prevent gas diffusion between older and newer layers; hence the gas is the same age as the ice.
(3) Liquid water is present in ice, even at very cold temperatures, allowing CO2 to go into solution under pressure.
(4) Samples are contaminated in a variety of ways, primarily by drilling fluid.
(5) Samples crack in situ, during extraction and handling, permitting gases to diffuse between bubbles.
(6) A host of other physical and chemical processes change gas concentrations in ice, making measurement unreliable.

All of these are perfectly reasonable concerns, but the way Jaworowski and colleagues go about exploring them is not that of well-meaning critics trying in good faith to improve the science. Rather, their arguments at every turn are directed to calling into question the reliability of any ice core measurements, and disputing any conclusions drawn from them.

The paper makes much of the fact that the typical reported values of CO2 concentration for air extracted from ice have changed over the decades. This should not be too surprising: as the discipline evolved and measurement methods improved, researchers have learned how to do a better job. But Jaworowski et al. argue instead that the earlier measurements should cast doubt on the later ones:

Two important observations were made in these early studies. It was found that the CO2 content of the air trapped in pre-industrial and ancient ice is rather high, and has a very wide concentration range of about 100 – 7400 ppm (Table 1). Even more important was the finding that several physical and chemical processes … lead to differentiation of the original atmospheric ratios of N2, O2, Ar and CO2, and to depletion or enrichment of CO2 in the ice.

Here is Table 1:


In Table 1 we see the early history of a rapidly improving science. In many of the papers cited by this one, researchers quite openly discuss the limitations of their methods, and the steps they have taken to improve them. But Jaworowski et al. use the changing nature of the discipline to argue that we shouldn’t trust the whole business. This does not seem like an argument offered in good faith.
Their argument regarding the age of the “close-off” layer is even worse. At the time this paper was written, some very good research had been done showing that there is substantial mixing of air down to the firn-ice transition layer (And quite a bit more has been done since then.) Some of the most convincing evidence for this mixing, and thus for an age difference between air and ice, is the gradient in heavier isotope concentration caused by gravitational enrichment right down to the transition layer, where it levels off dramatically. Jaworowski et al. either ignore this research, or try to turn it to their purposes. They dismiss one 1982 article by Craig and Chou, saying that a 1988 article by Craig et al. had “revoked their earlier assumption” regarding the age difference. They then turn around and cite another 1988 article by Craig and a different set of collaborators, saying that the enrichment “strongly indicates that the air in porous firn is protected from convective and other motions.” So, gravitational enrichment is unreliable as an indication of how long the air has been mixing, but it is reliable as an indication that there is not much mixing?
Their argument regarding liquid water in polar ice is mostly hand-waving. For example. they cite the discovery by Mulvaney et al. of liquid sulfuric acid at grain boundaries as providing “conditions for diffusion of gas from bubbles to or from the intergranular liquid.” To describe this as speculative may be too kind, given the extremely tiny volume of the liquid inclusions, and the absence of any evidence (or even a plausible mechanism) for the proposed effect.
The extensive recitation of supposed problems with sample contamination suffers from the same defects as the other discussions. Jaworowski et al. list a number of cases where samples were believed to have been contaminated, then imply that the problem is endemic and inevitable, and that it makes all gas measurements from ice cores suspect. Nowhere would the reader learn that great care is taken to avoid contaminating ice samples, that techniques are constantly improving, or that drilling fluids are chosen for, among other properties, their lack of interaction with the studies being performed. This section seems to be an attempt to throw everything that comes to hand at the subject, and hope that something will stick.
Sample cracking? See above. Similar to the other discussions, this is an unorganized listing of cracking mechanisms in ice, coupled with vague assertions that this will lead to mixing of gases and unreliable results. In fact, most observations indicate that the bubbles in ice cores are substantially isolated from one another up to the point of crushing in the sample chamber. More to the point, Jaworowski et al. owe us some explicit theory of how their proposed mechanism might affect the results. Even if there was mixing among bubbles in samples, how rapidly would gases diffuse, how could we predict the type and magnitude of the effect, and how might the predicted results be made to agree with observation? We are given no hint.
Lastly, just in case we can still see through the smoke cloud generated by the earlier arguments, Jaworowski et al. give us a list of the processes active in ice cores and invalidating measurements from them:

This is just another laundry-list of supposed problems, masquerading as a summary of detailed criticism. By attempting to make up in volume what it lacks in argument. this table exemplifies everything that is wrong with the paper.

If Jaworowski et al. had taken even one of these processes, developed an explicit and detailed theory of how it might affect measurements of gases in ice cores, proposed an experiment to test that theory, then performed the experiment and reported the results, they would deserve more respect.

If they had acknowledged that they were discussing a vital and rapidly changing area of science, and that improvements in technique were to be expected, their arguments would have been better received.

If they had evinced a willingness to identify specific problems and develop solutions to them in a constructive spirit, their criticisms would have been welcomed by the research community.

Unfortunately, however, this very ambitious paper was shaped from the beginning by its mission: to undermine the credibility of ice core research generally, and thus to weaken any recommendations that might arise from it. Except for one paragraph at the end, this paper offers no proposals to improve the science. Instead, whenever a valid criticism threatens to grow into a constructive suggestion, the mission takes over and turns discussion to another unhelpful blanket attack on the research. Sadly, this ideological bent has poisoned and largely destroyed the value of what might have been a valuable contribution.

5 Responses to “Jaworowski et al.‘s 1992 article in The Science of the Total Environment

  1. Eduardo Ferreyra Says:

    You said: “this ideological bent has poisoned and largely destroyed the value of what might have been a valuable contribution,” which means that, leaving aside his ideological bent (opposed to your ideological bent on global warming, that cancel each other and makes things even) the paper IS an extremely VALUABLE CONTRIBUTION, no matter how brilliantly you can twist arguments and use rethoric and dialectics to discredit Jaworowski’s work.

    And in point 3, you imply there is no liquid in ice allowing for CO2 coming into solution, so Jaworowski must be wrong. You seem to forget recent claims that water under Greenland’s ice pack is moving the ice pack towards the sea, and this water is caused by melting by global warming that seeps through the ice to the bottom!

    You should contact other people before making claims because we have seen already too many contradicting claims among the Warming Wolf Pack.

  2. site admin Says:

    It is good to see that someone is reading this post, even if the commenter appears to be somewhat confused.

    … his ideological bent (opposed to your ideological bent on global warming, that cancel each other and makes things even)

    Exactly wrong. The only thing that matters here is the science. Period.

    If the ice core record really were suspect for the reasons Jaworowski cites, or if reliable measurements really did indicate that pre-industrial CO2 levels were as high as he claims,[1] then we would see some confirmation of those claims in the literature. But we don’t. Are all climatologists and glaciologists, then, engaged in a vast conspiracy to suppress all opposing opinion? No. The scientific community does not take Jaworowski seriously because his arguments don’t make any sense. He is, however, taken seriously by climate-change denialists — precisely the group of people who believe passionately that climate change is essentially a political issue. It is not. It is a scientific issue, and it is precisely the science that Jaworowski has gotten inexcusably wrong.

    And, as to

    … water under Greenland’s ice pack is moving the ice pack towards the sea, and this water is caused by melting by global warming that seeps through the ice to the bottom!

    You seem to be saying that there is liquid water somewhere in the vicinity, and hence there must be liquid water in the ice cores. Seriously — WTF? As was said in a different context, “the mind boggles.”

    [1] If he actually makes a quantitative claim, that is. Jaworowski is positive that pre-industrial CO2 concentrations were higher than the ice cores indicate, but he seems reluctant to make a testable claim as to just how high they were.

  3. Yelling Says:

    Eduardo: While most of your post seems to be unsupportable rhetoric I do commend you for making some testable statements. This is one of the cornerstones of the scientific process. I would encourage you in the future to be more specific in your statements since what you post could be taken in several ways.

    For example your statement: “and this water is caused by melting by global warming that seeps through the ice to the bottom! “

    Now, it is not clear if it is the global warming (I assume you mean downward longwave radiation) that is seeping to the bottom or the liquid water that is seeping towards the bottom. But in fact we can look at both and see if this is a reasonable statement.

    If you are referring to the longwave radiation all you need to do is to look at the spectral characteristics for ice and you will see that it is quite opaque to IR (which is what you would expect since glacial ice is often blue).

    On the other hand if you meant that the liquid water was seeping down we first need to look at the possibility of liquid water being generated. Considering the average summer temperature of Greenland and the fact that the top of the glaciers is at an elevation of about 3,000 km I would suspect that there is little generated. If there were, I am doubtful of it penetration too far since the top 1000 meters of ice is at a temperature well below freezing.

    So I am afraid that statement does not stand up to scientific scrutiny. However, we can look at others if you wish.

    Regards,
    Y.

  4. gh Says:

    The main article seems to have a tone of very hurt feelings – maybe Jaworowski did something else to him in the distant past. One of the replies mentions no research – if you look carefully you will find that Jaworowski tried to get funding for a study and was turned down. Phrases such as “immoral” connected to concepts of causing people to question global warming – back in the 1990s – shows that this has been going on for some time and very one-sided at that. A real question – Was the study ever done – being a rank amateur this was one of the first questions I had ( does co2 change while in the ice over 100s,1000s,1000000s … of years – how about my ice cubes for a start. When someone is refused funding about a fundamental question in the science he isn’t the one who loses credibility or is “immoral”.

  5. Robert Kernodle Says:

    [“This paper fails to present any coherent explanation of why ice core measurements in general should be considered unreliable.”]

    FAILS to present any coherent explanation!?? — This is plainly false, as anyone who reads the paper will clearly see 57 pages of meticulous, detailed explanations.

    [“Instead, Jaworowski and colleagues develop an unconnected list of complaints regarding ice core methodology, without presenting any testable theories as to what the effects of those problems should be.”]

    UNCONNECTED list of complaints!? — without presenting any testable theories!? — Again, anyone reading this paper will see a very detailed list of potential problems with ice core analysis. To merely call this detailed list “a list of complaints” is false labeling , since this list is quite a bit more precise than mere “complaints”. The authors show photographs and diagrams of physical structures in ice that support their detailed list of potential problems. Who says (besides you) that the evidence supported by these photos and diagrams cannot be tested?

    [“In some cases, e.g. their assertion that the “age assumption” regarding firn consolidation is unproven, they ignore successful research that contradicts their thesis.”]

    Please cite your sources of the specific, relevant research that you seem to be aware of that you claim the authors “ignore”. “IGNORE” is an accusation of wrongdoing, which is suspicious, since you really probably do NOT know the authors.

    [“In other cases, as noted in connection with the history of atmospheric CO2 measurement, they distort the conclusions of other researchers in an apparent attempt to spread a cloud of doubt over the entire enterprise.”]

    They do no such thing. They lay out a timeline and related history of atmospheric CO2 measurements, and they show inconsistencies in how the numbers in the records seem to change. You tacitly assume that improved methods of measurement are the reason for differences in numbers over the years, but can you rule out bias based on the previous records’ values in light of a preferred point of view that developed for more political than scientific reasons??

    That’s all for now,

    RK

Leave a Reply