Accelerated warming of the Southern Ocean and its impacts on the hydrological cycle and sea ice? refers, as does Curry’s comments in the comments. I suspect we’re now at the going-round-in-circles stage, but it is probably worth one more spin.

Curry begins rather gracelessly:

William, all of these issues were discussed ad nauseum over at WUWT, on three threads. These are certainly valid questions, but not particularly interesting ones IMO, which is why I was not motivated to answer them until repeatedly queried (including email) about them.

The WUWT thread(s) are sprawling and generally far from the point, and (when I last looked) failed to cover the important issues in any meanginful or focussed way. And contrary to the impression that Curry is giving, I certainly wasn’t badgering her by email.

Below, I’ve put in Curry’s comment, which is essentially my original bullet-listed “major errors” together with her replies. Note that the “bullet-list” isn’t in the original post: I only added that in the comments when Curry, well, pretty well wouldn’t read the post and reply; it needed to be condensed to that before she would reply. Or, put another way, there is more in the original post that she hasn’t replied to (there is an entire section “Looking at the paper – models” that she has ignored). And I don’t think her replies below are substantive: instead they are evasive. In a sense this is what you’d expect: she is busy, the paper has been published, she can’t afford to admit to any real flaws in it.

1) you use data from 1950-1978 that is clearly meaningless.

Reread the 2nd para of the introduction. The problem with the data is acknowledged. The data from 1950-1978 is not meaningless. There is data in the region during these periods. Missing data in the two SST data sets is filled in by an EOF analysis. The two different SST analyses give reasonable agreement in the period post 1950 (they diverge sharply prior to 1950). Our analysis of the trend is broadly consistent with other assessments of the temperature trend that are cited in the introduction.

This won’t do. It is no good waffling about the EOF analysis filling in the data; it is absolutely clear from the zonal averge plots that WE provides (which in turn simply reflect what everyone, including Curry, knows full well) that before 1978 the data isn’t usable over large regions.

2) this data contaminates the entire (obs) analysis.

The obs analysis is a minor part of the paper, intended to compare with the model simulations that were the main source of data used in the analysis. The whole issue of filling in missing ocean obs using an EOS analysis is definitely troublesome, particularly prior to 1950. In fact it makes me really queasy about the “unequivocal” confidence of the IPCC. William, let me know if you are prepared to throw out both the baby and the bath water on this one.

This is now attack-as-defence: yes, her analysis may well be junk, but in that case so is the IPCC’s, ha ha. Again, this won’t do. The issue is her paper (though if anyone wants to raise the IPCC temperature records, I’m happy to do so, but not here: it is a red herring). Calling the obs analysis a “minor part” of the paper is an evasion, and notice how she has skipped the essential point: does she agree that the missing data contaminates the entire analysis? We don’t know because she won’t say. I think that Curry is not very familiar with EOF analysis, so genuinely doesn’t know the answer. Which would be fair enough, had she simply answered “don’t know”.

3) the hypothesis that you put forward is not novel.

We cite the Zhang 2007 paper that describes a different mechanism that is not inconsistent with ours, but does not include the atmospheric hydrological cycle. I probably read the Manabe et al. paper back in the 1990′s, but didn’t recall it as we were writing this paper. Did any of you (other than Grumbine) actually read the Manabe paper? There is one statement in the Manabe paper that is relevant: ” the reduction in surface salinity resulting from the increase of freshwater supply at the oceanic surface is mainly responsible for the weaker convective activity in the G integration.” This statement is made in a paragraph discussing the deep ocean convection in the Southern Ocean. Manabe doesn’t discuss the increasing sea ice extent in this context. Grumbine connected the dots in the Manabe et al. paper and came up with generally the same idea we did (we came up with the idea via a different route), and describes it in a half sentence. So, our hypothesis is not put forward per se in the Manabe et al. paper. I occasionally check in at Grumbine’s site, didn’t spot his post on the Antarctic sea ice. Note, the Zhang paper did not cite the Manabe paper either; it just doesn’t say much about the Antarctic sea ice.

Since I’ve crit her above for failing to say don’t-know when appropriate: no, I haven’t read the Manabe paper properly. I think her defence, above, is possible but rather weak, and amounts to half admitting the criticism (They mention increasing snowfall in the context of oceanic deep convection but not in the context of sea ice in a comment lower down pretty well admits it). Eli is less kind. In way, I don’t care too much about this issue, as it has no impact on the correctness of the results: it is just part of the general malaise of carelessness.

[Update: I really should ahve read the paper rather than taking Curry's word for the contents. This is yet another example of her carelessness. As Lazar points out in the comments there is far more. The claim for novelty in LC looks very weak indeed now -W]

4) you could have used an extra decades worth of obs data.

The purpose of the obs data was to demonstrate the consistency of the 20th century climate model simulations with the observations. Data from 2000-2010 would not have helped here, since the AR4 climate model simulations do not extend past 2000.

This is evasion / wrong. Using 2000-2010 would have given an extra decades worth of good observations. The C20C simulations end in 2000, of course, but patching them onto the 21st century simulations is quite reasonable.

5) there is no justification for the EOF analysis.

EOF analysis is basically a filtering technique. You can conduct an analysis with the original data, or with filtered data. The latter can clarify the signal. In this particular paper, the EOF analysis didn’t filter all that much. If the study had been conducted with the original data, it would have been more easily understood by a broader audience. The use of EOFs arguably complicated the analysis, but did not in any way compromise the analysis. Jiping Liu prefers to use EOF analysis; I do not. I think I’ve convinced him not to use the EOFs in future papers unless there is a clear advantage that outweighs the addition of the complexity.

I think what this is saying is that yes, using the EOFs was a mistake, so that is good. I could have used a better word than “justified”, or I could have explained it better. What I meant was that there was no justification in the paper for using EOFs. It is just done, with absolutely no hint as to why it is a good idea. Had they attempted to write down why it was a good idea, they might have realised that actually it wasn’t. Also, I don’t think that “You can conduct an analysis with the original data, or with filtered data” is correct here. EOF was their data-reduction technique. They could, instead, have used take-the-trends as their technique. But either way, you can’t use the original data, because (obviously) there is too much of it. You always need some data reduction. Take-the-trends would have the advantage of not corrupting the rest of the field.


  1. #1 Eli Rabett

    Using the 2000-2010 data if nothing else would help with smoothing/filtering the 20th century data by reality instead of whatever or EOF

  2. #2 dhogaza

    And contrary to the impression that Curry is giving, I certainly wasn’t badgering her by email.

    To be fair to Curry, I, at least, didn’t get the impression that she meant that it was you badgering her in e-mail.

    [Oh well, maybe I'm being too sensitive. But if it wasn't a complaint, what was the point in her writing it? -W]

  3. #3 dhogaza

    This is now attack-as-defence: yes, her analysis may well be junk, but in that case so is the IPCC’s, ha ha. Again, this won’t do

    When I first read her statement, I thought it was totally bizarre. Sort of the “they started it!” defense.

  4. #4 Hank Roberts

    > Grumbine connected the dots

    Grumbine doesn’t claim he connected the dots; he pointed out in March that WUWT had got it backwards:

    “The recent article at WUWT [NSIDC Reports That Antarctica is Cooling and Sea Ice is Increasing] trumpets the observation that Antarctic sea ice is increasing. This is expected from climate modeling. Nice to see someone else is picking up on this interesting confirmation of our scientific expectation.”

    Pity no one among the 300+ comments in that WUWT thread mentioned that Grumbine had pointed out Watts’s mistake.

    Hmmmmm … a Zenn diagram exercise:

    Published scientists who do vs. don’t post at WUWT;
    published scientists who knew vs. didn’t know the dots;
    “3 reviewers at Science and 3 reviewers at PNAS.”


    But, as William says, this “has no impact on the correctness of the results.”

    [Zenn diagram? Is that a more peaceful version of a Venn diagram ;-? -W]

  5. #5 Chris S.

    “a Zenn diagram exercise”

    I like it – what is the sound of one denialist thinking?

    Zen says none of us really experience existence, because we are too busy experiencing our own subjective version of existence. Some people more than others…

  6. #6 Hank Roberts

    > Zenn

    “I am he as you are he as you are me
    And we are all together” — Lennon/McCartney

    “… and have to get good at it.” — Stewart Brand

    Blog math: define a Zenn diagram as a Venn diagram in historical perspective: all the people contending on an issue, taken together, produce the sum of their efforts.b

    Looking back from, say, 2100 — how are we doing here?

  7. #7 Robert Grumbine

    Much as I’d like to take credit for having connected dots, I really can’t. On one hand, if I truly were the person to have noticed that it is the snow that is important on ice as well as on ocean, then I missed the opportunity to scoop Liu and Curry by 10-15 years. It’s certainly an old comment of mine, going back quite a few years in sci.environment (that’s a sign of how old it is, as I haven’t been active there in a long time). Related hand: I have a lot of notions like this, which I consider to have been introduced by other people, but might be argued that it’s more my creativity, connecting the dots, than the original authors’ idea. In that case, I have a ton of writing to be doing (at home as most of these don’t connect to my work). Could be.

    But the real reason I have to disclaim any creativity here is that Manabe told me about the snow on ice business himself in the 1990s. Certainly he’d told me about it no later than the “Workshop on polar processes in global climate. 13-15 November 1996. Cancun, Mexico.” (I was part of the organizing committee; how we wound up in Cancun is a story. Our original target was McMurdo Sound, Antarctica.) Given that we’re talking about Manabe, I find it unlikely that I’m the only person to get the story out of him. He was far from bashful about talking about his work.

    Love the Zen diagram imagery.

  8. #8 Hank Roberts

    Zwalley et al. (2002) explicitly connected the dots, as I read it. Eli’s got the quote (“the counter-intuitive result …”).

    Ironically, Watts seems to have locked the posting
    not long after Grumbine noted WTF’s mistake. Pity he didn’t warn his readers about the bad information there.

  9. #9 John N-G

    “Hmmmmm … a Zenn diagram exercise: ”

    Almost perfect, change the ‘H’ to an ‘O’ and you’re there.

    If I may summarize:

    1. The paper’s wrong because the statistical method is wrong.
    2. The paper’s wrong because the data set is faulty.
    3. The paper’s wrong because it doesn’t acknowledge certain other papers.

    Never mind that according to Manabe and Zwally, the paper’s right anyway.

    All of this sounds remarkably like the criticism Mann’s papers receive from the other side, with the same bottom line:

    Whether this particular paper is good or bad doesn’t affect our understanding of the scientific problem at hand.

    [Your point 3 at the very least is wrong, because I've explicity said that it doesn't affect the validity of the paper. Points 1 and 2 are wrong, because you've failed to understand the arguments and havve used the wrong words: I don't know if the papers conclusions are right or wrong, but what I am saying is that the methods used to achieve those conclusions don't look valid.

    Perhaps this becomes clearer with a simple example:

    1. Stoats are nice.
    2. Things that eat mice are nice.
    3. Therefore, stoats are mustelids.

    3 doesn't logically follow from 1 and 2, so the argument is invalid (or wrong, if you prefer). But the conclusion - point 3 - is nonetheless true. You can't disprove a conclusion by pointing out that the methods are wrong.

    I hope that you understand the distinction now -W]

  10. #10 Rocco

    John N-G:

    “All of this sounds remarkably like the criticism Mann’s papers receive from the other side,”

    Actually, that would be more like:

    “The Accelerated warming of the Southern Ocean is a classic from years back, that has now been proven to be a fraud perpetrated by those pushing a liberal agenda, and using the debunked theory of man-made global warming to justify it. The graph was a centerpiece of Al Gore’s fear-mongering…” :)

  11. #11 John N-G

    I suppose folks like McIntyre would use a slightly different simple example, but to continue the analogy, he is forever protesting that people take his very specific criticisms and interpret them overly broadly. You now know what it feels like.

    Sorry for my own over-simplifying and over-generalizing.

  12. #12 John N-G

    …and I’ve got to stop posting comments after giving back-to-back lectures to non-majors. Makes me too punchy. I think I just did a ‘Judy Curry’.

    I need another one of those Zenn diagrams.

  13. #13 MarkB

    The McIntyre tribe would say something like “Liu and Curry, defended by The Team, selected inappropriate data and time periods, ignored data that doesn’t match the IPCC message, manipulated results, clearly engaged in misconduct, dismissed dissenting views, and ultimately pushed the notion that Antarctic Sea Ice will melt, based on fudged computer models, when data clearly shows otherwise. Read ‘The Antarctic Ice Illusion: CurryGate and the Corruption of Science’ by Montfork. It’s one of the best books written on climate science, though I can’t personally vouch for any of its conclusions.”

  14. #14 Lazar

    JC writes;

    “There is one statement in the Manabe paper that is relevant: ” the reduction in surface salinity resulting from the increase of freshwater supply at the oceanic surface is mainly responsible for the weaker convective activity in the G integration.” This statement is made in a paragraph discussing the deep ocean convection in the Southern Ocean. Manabe doesn’t discuss the increasing sea ice extent in this context.”

    That is not true… on the next page (113)…

    “In sharp contrast to the situation over the Arctic Ocean, the change of sea ice is relatively small in the circumpolar ocean of the Southern Hemisphere, with the exception of the Weddell and Ross seas, where it increases substantially from the S to G integrations (Figs. 11a and 11c; Figs. 11b and 11d) despite the increase of atmospheric carbon dioxide. Because of the reduction of surface salinity due to the increased water supply at the oceanic surface, the convective mixing between the mixed layer and deeper ocean becomes less frequent, slightly lowering surface water temperature and increasing sea ice thickness in both the Weddell and Ross seas, as discussed in Part I of this study.”

    Part I says (795)…

    “It is surprising, however, that the sea-ice thickness in the G integration increases significantly in the immediate vicinity of the Antarctic Continent despite the increase of atmospheric carbon dioxide. This is consistent with the slight reduction of sea surface temperature mentioned earlier (Fig. 10a). It will be shown in section 9a that, owing to the intensification of the near-surface halocline caused by the increased supply of water at the oceanic surface, the convective mixing of cold near-surface water with warmer, underlying water becomes less frequent, resulting in the increase of sea ice and slight reduction of sea surface temperature.”

    Section 9a says (811)…

    “Although the efficient vertical mixing may be the most important factor responsible for the smallness of sea surface temperature change in the Circumpolar Ocean of the Southern Hemisphere, it does not explain why the change is practically zero or sometimes reversed in sign. As noted by Manabe et al. (1990) based upon the detailed analysis of the heat budget of the Circumpolar Ocean of their model, the reduction of convective activity in the surface layer is responsible for this interesting phenomenon. For example, in response to the increase of atmospheric carbon dioxide, the excess of precipitation over evaporation increases, and surface salinity is reduced in high latitudes as noted in section 8. Thus, the static stability of the near-surface water increases and the convective mixing of cold surface water with the relatively warm subsurface water is reduced, thereby contributing to the reduction of sea surface temperature in the Circumpolar Ocean. This is why sea surface temperature hardly changes and sea ice slightly increases near the Antarctic Continent in response to the increase of atmospheric carbon dioxide.”

    … all of which information was placed front and center in Zwally et al. 2002, which was cited by Liu and Curry in 2004.


    Manabe, S., R. J. Stouffer, M. J. Spelman, and K. Bryan (1991), Transient Responses of a Coupled Ocean-Atmosphere Model to Gradual Changes of Atmospheric CO2. Part I. Annual Mean Response., Journal of Climate, 4(8), 785-818, doi:10.1175/1520-0442(1991)004<0785:TROACO>2.0.CO;2.

    Manabe, S., M. J. Spelman, and R. J. Stouffer (1992), Transient Responses of a Coupled Ocean-Atmosphere Model to Gradual Changes of Atmospheric CO2. Part II: Seasonal Response., Journal of Climate, 5(2), 105-126, doi:10.1175/1520-0442(1992)005<0105:TROACO>2.0.CO;2.

    [Oh dear, what you can find if you actually read the paper :-) -W]

  15. #15 Hank Roberts

    Dr. Curry?

    Are you relying on someone else for your information about what is in the papers? I wonder if you may be relying on a grad student who’s perversely afraid to give you bad news, and so making things worse.

    Stuff happens. Something’s wrong.

  16. #16 Hank Roberts

    Here’s a bit from and link to the National Geographic’s piece from a few weeks back, for reference:
    … Antarctic sea ice has mysteriously expanded, according to study leader Jiping Liu, a research scientist at Georgia Tech in Atlanta.

    “We’ve seen this paradox, but we don’t know why—here we gave an explanation,” Liu said.

    The study results aren’t surprising, since they’re in line with previous predictions that Antarctic sea-ice loss would accelerate, said Walt Meier of the National Snow and Ice Data Center (NSIDC) in Boulder, Colorado.

    “That’s been the conventional wisdom—this is a modeling study [that] does actual physics that confirms” this idea, Meier said.

  17. #17 Chris S.

    Have you seen CruHack Tom making a fool of himself at Tobis’ place? Gish would be proud.

  18. #18 Hank Roberts

    Where’s … um … I just noticed this mention:

    “… this just in — a few weeks ago I took part in a conference call about global warming with the folks at The Nature Conservancy which they transcribed and posted (it starts on page 8 in their Science Chronicles publication). Interestingly they chose as their climate scientist the feisty Dr. Judy Curry.”

  19. #19 Hank Roberts

    And here it is, and it’s even topical:

    [But by trying to isolate a certain group of people and call them “skeptics” and then put too high a confidence level on the scientific findings, I think that’s how we lost the trust of the public. - so it doesn't look like she has learnt anything -W]

  20. #20 Hank Roberts

    “Arctic sea ice is next up on my list of pure science technical threads, I’ve started collecting material, but it will take a little while to pull this together.”

    [Might be fun. I commented no the new blog over at mt's place -W]