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West Antarctica: still warming

The temperature reconstruction of O’Donnell et al. (2010) confirms that West Antarctica is warming — but underestimates the rate

Eric Steig

At the end of my post last month on the history of Antarctic science I noted that I had an initial, generally favorable opinion of the paper by O’Donnell et al. in the Journal of Climate. O’Donnell et al. is the peer-reviewed outcome of a series of blog posts started two years ago, mostly aimed at criticizing the 2009 paper in Nature, of which I was the lead author. As one would expect of a peer-reviewed paper, those obviously unsupportable claims found in the original blog posts are absent, and in my view O’Donnell et al. is a perfectly acceptable addition to the literature. O’Donnell et al. suggest several improvements to the methodology we used, most of which I agree with in principle. Unfortunately, their actual implementation by O’Donnell et al. leaves something to be desired, and yield a result that is in disagreement with independent evidence for the magnitude of warming, at least in West Antarctica.

In this post, I’ll summarize the key methodological changes suggested by O’Donnell et al., discuss how their results compare with our results, and the implications for our understanding of recent Antarctic climate change. I’ll then try to make sense of how O’Donnell et al. have apparently wound up with an erroneous result.

First off, a reminder for those not familiar with it: the essential innovation in our work was to combine the surface temperature data available from satellites with the ~50 years of data from weather stations. The latter are generally considered more reliable and go back a full 50 years, but are very sparse and incomplete, whereas the satellite data provide complete spatial coverage of the continent, but only since the early 1980s. We combined the two data sets by calibrating the weather station data against the satellite data, and using the calibration to get a complete spatial picture of Antarctic temperature variability and trends for the last 50 years. The key findings were that the overall Antarctic trend was positive (but not necessarily statistically significant), and that in West Antarctica, the trends were both positive and significant, especially in winter and spring. These findings were important enough for Nature to publish them because most researchers thought that significant warming was restricted only to the Antarctic Peninsula region. None of these findings is contradicted by O’Donnell et al.’s results.

O’Donnell et al. have three main criticisms of our work. First, that the reconstruction we reported was not homogenous. That is, the first part of the reconstruction (1957 through 1981) is based entirely on a linear combination of weather station data (since there are no satellite data during that period); while the second part (1982-2006) is derived simply from the satellite data. O’Donnell et al argue that it would be better to use the only weather station data for both periods, since these data are a priori considered more reliable. (There are all sorts of potential problems with the satellite data, the chief one being that there is a ‘clear sky’ bias.) That is, one wants to calibrate the data during 1982-2006, and then use that calibration to model the temperature field for both the early and the later periods, using only the weather stations.

Second, that in doing the analysis, we retain too few (just 3) EOF patterns. These are decompositions of the satellite field into its linearly independent spatial patterns. In general, the problem with retaining too many EOFs in this sort of calculation is that one’s ability to reconstruct high order spatial patterns is limited with a sparse data set, and in general it does not makes sense to retain more than the first few EOFs. O’Donnell et al. show, however, that we could safely have retained at least 5 (and perhaps more) EOFs, and that this is likely to give a more complete picture.

Third, O’Donnell et al. argue that we used too low a truncation parameter when doing the ‘truncated least squares’ regressions. In general, using too low a truncation parameter will overly smooth the results, and tend to smooth both temporal and spatial information. The problem with using too large a truncation parameter is that it creates problems when data are sparse, resulting in numerical noise (overfitting). O’Donnell et al. try to get around this problem by using cross validation — that is, trying a bunch of different truncation parameters, and using the ones that give the maximum r2, RE and CE statistics.

There are a number of other criticisms that O’Donnell et al. make, such as whether it is okay to infill the weather station data at the same time as doing the calibration against the satellite data (as we did) or whether these have to be done separately (as O’Donnell et al. did). These are more technical points that may or may not be generally applicable, but in any case do not make a significant difference to the results at hand (as O’Donnell et al. point out).

Let’s assume, for the moment, that all of these ideas are on the mark, and that the main reconstruction presented by O’Donnell et al. is, in fact, a more accurate picture of Antarctic temperature change in the last 50 years than presented in previous work. What are the implications for Antarctic climate? How would they differ what was concluded in Steig et al. (2009)? The answer is: very little.

The spatial patterns of annual trends, and how they evolve through time, is similar in both papers. In particular, O’Donnell et al. find, as we did, that the entire continent was warming, on average, prior to early 1980s (Figure below from their main “RLS” reconstruction). As we said in our paper, this would tend to support the idea that cooling in East Antarctica is a recent phenomenon at least in part attributable to recent trends in the Southern Annular Mode (SAM), which is itself forced (at least in part) by stratospheric ozone depletion.

O’Donnell et al. also reproduce our finding that the seasons in which the most rapid and significant warming is occurring are winter and spring — in large areas of both East Antarctica and West Antarctica. In spring, warming is significant throughout all of West Antarctica through the entire 50 years of the record, and in winter, it also occurs throughout all of West Antarctica in the last 25 years. In both seasons in this latter period, the locus of greatest warming has been West Antarctica, and particularly the Ross Sea region and Marie Byrd land, not just the Antarctic Peninsula as virtually all studies prior to ours had assumed. This is an important result that we highlighted in our paper because it has implications for our understanding of the dynamics involving Antarctic warming. Specifically, we made a model-data comparison in the paper, in which we said

… both in the reconstruction and in the model results, the rate of warming is greater in continental West Antarctica, particularly in spring and winter, than either on the Peninsula or in East Antarctica…. This is related to SST changes and the location of sea ice anomalies, particularly during the latter period (1979–2003), when they are strongly zonally asymmetric, with significant losses in the WestAntarctic sector but small gains around the rest of the continent.

In other words, during the period where we have good sea ice data, areas with little sea ice are always areas of surface warming in the Antarctic. It was already well established before our work that sea ice anomalies play a major role in the observed waring on the Antarctic Peninsula’s west coast. Our work showed that this is also true in West Antarctica, and is fully confirmed by O’Donnell et al.’s analysis. The only point of disagreement is in winter, in the earlier part of the record only (prior to the satellite era).

Another point of complete agreement between our results and O’Donnell et al. is that the most widespread cooling occurs in fall — not summer as discussed in earlier work (e.g. Thompson and Solomon, 2000). This may be something of a problem for the hypothesis that ozone depletion is a major driver of the observed East Antarctic cooling, because the forcing is occurring in spring (when the ozone hole develops). If there is a link between the spring forcing and fall temperature, it is not a simple one, but likely would include a role for sea ice, which offers an obvious source of persistence from season to season (a paper in review by Arnour and others argues exactly this point).

Finally, O’Donnell et al. agree with us on the most basic result of all: there is statistically significant warming in West Antarctica. In this context, it is worth being very clear on what is meant by “West Antarctica”. Reading what has been said about O’Donnell et al. in various places in the blogosphere, one would get the impression that their paper returns the warming of Antarctica to its ‘rightful’ place, the Antarctic Peninsula alone. If that were true, it would certainly be a significant refutation of our work. But in the actual abstract of O’Donnell et al., it is stated that “we find that statistically significant warming extends at least as far as Marie Byrd Land.” Marie Byrd Land is that part of West Antarctica that extends eastward from the Ross Ice Shelf up past Byrd Station and over the central West Antarctic Ice Divide (see the map above). In O’Donnell’s results, there is significant warming all the way from the Peninsula westward past WAIS Divide site, at 112°W, well within Marie Byrd Land and nowhere near the Antarctic Peninsula. Prior to our work, no one had claimed that any area outside the Peninsula was warming significantly. Borehole thermometry at WAIS Divide (Orsi and Severinghaus, 2010) and at the Rutford Ice Stream (closer to the Peninsula; Barrett et al,. 2009) has since provided completely independent validation of these results. O’Donnell et al. is thus merely the latest of several studies to confirm our original finding*: West Antarctica is warming significantly.

To be sure, there is real disagreement between our results and those of O’Donnell et al. For the full fifty year reconstruction of temperature trends, the main reconstruction they discuss in the paper shows cooling in the winter and fall over the Ross Ice Shelf, which contrasts with our finding of significant warming there. As a consequence, their overall warming trends are smaller, by about half. These are the only important differences between our results and those of O’Donnell. Nevertheless, they are significant differences, and certainly may be important for our understanding of Antarctic climate change. In particular both results would tend to suggest a greater role for natural variability than our findings implied. If O’Donnell et al.’s results are correct, this would suggest that the damped response of Antarctica to global radiative forcing (i.e. CO2 increases) that is commonly seen in models (as discussed previously by Spencer Weart, for example) is perhaps more on the mark than our paper would suggest (though note that even the much larger trends we estimated are still significantly damped compared with the Arctic.)

Let’s return now to the question of whether O’Donnell et al.’s results actually do represent an improvement over ours. The figure below indicates a rather glaring problem: O’Donnell et al. disagree markedly with the raw weather station data from Byrd, which is the only record of any length anywhere in West Antarctica. Shown in the figure, reproduced again below, are the main reconstructions of Steig et al. (2009) (green) and O’Donnell et al. (2010) (blue), compared with the the actual raw data (black) from the Byrd weather station. The simple linear trend on the raw data is nearly four times larger in reality than shown by O’Donnell et al., whereas it is not statistically distinguishable from Steig et al. There are a lot of missing data from Byrd (and annual means in the figure include some missing months), so also shown in the figure (dashed) is an independent infilling of missing data from Byrd station, done by Andy Monaghan (using no satellite data whatsoever, as described in Monaghan et al., 2008, plus new data available through 2009). The updated Monaghan estimate — currently under review — indicates an even higher trend, >0.4°C/decade, when the data are updated through 2009.

The evident failure of O’Donnell et al. to correctly capture what is going on at Byrd (and presumably elsewhere in West Antarctica) is quite surprising, given that one of key differences in their methodology is to use the weather station data — not the satellite data as we did — as the verification target. That is, O’Donnell et al. use weather stations, withheld one at a time from the reconstruction for verification purposes to optimize their calibration. How then, can they be so far off for the location of the most important weather station? (I say ‘most important’ here because the main point of contention is, after all, West Antarctica). There are three likely sources of the problem, each pertaining to O’Donnell et al. implementation of their suggested modifications to the method we used.

First, as I noted above, O’Donnell et al. use a linear combination of weather station data for their reconstruction, both in the reconstruction period (pre-1982) and in the calibration period (the satellite era, post 1981). This is a very reasonable thing to do, resulting in a more homogeneous data set than ours. However, it also means throwing out information that might be important: namely, that there are strong trends in the temperatures in West Antarctica that may not be captured by any weather station data. This is not a very large problem in East Antarctica, where the scale of spatial covariance is large, and the number of weather stations is also large; it is a potentially huge problem in West Antarctica, where the number of stations is small (again, only Byrd goes back beyond the satellite era) and the spatial scale of covariance is also smaller, due to the greater topographic relief. On top of that, O’Donnell et al. do not appear to have used all of the information available from the weather stations. Byrd is actually composed of two different records, the occupied Byrd Station, which stops in 1980, and the Byrd AWS station which has episodically recorded temperatures at Byrd since then. O’Donnell et al. treat these as two independent data sets, and because their calculations (like ours) remove the mean of each record, O’Donnell et al. have removed information that might be rather important. namely, that the average temperatures in the AWS record (post 1980) are warmer — by about 1°C — than the pre-1980 manned weather station record. Note that caution is in order in simply splicing these together, because sensor calibration issues could means that the 1°C difference is an overestimate (or an underestimate).** Since Steig et al. retained the satellite data, we didn’t need to worry about this. O’Donnell et al didn’t have that luxury, and should at the very least have considered the impact of treating Byrd Station and Byrd AWS as entirely independent records.

Second, in their main reconstruction, O’Donnell et al. choose to use a routine from Tapio Schneider’s ‘RegEM’ code known as ‘iridge’ (individual ridge regression). This implementation of RegEM has the advantage of having a built-in cross validation function, which is supposed to provide a datapoint-by-datapoint optimization of the truncation parameters used in the least-squares calibrations. Yet at least two independent groups who have tested the performance of RegEM with iridge have found that it is prone to the underestimation of trends, given sparse and noisy data (e.g. Mann et al, 2007a, Mann et al., 2007b, Smerdon and Kaplan, 2007) and this is precisely why more recent work has favored the use of TTLS, rather than iridge, as the regularization method in RegEM in such situations. It is not surprising that O’Donnell et al (2010), by using iridge, do indeed appear to have dramatically underestimated long-term trends—the Byrd comparison leaves no other possible conclusion.

O’Donnell et al. do not rely entirely on ridge regression. They also present results from a more explicit cross-validation test, using various truncation parameters for a ‘truncated total least squares’ (or ‘truncated singular value decompositon’) regressions, as we did in our work. However, these tests, as implemented, are also problematic. O’Donnell et al. actually use cross validation in two steps: first, by filling in missing data in the weather station records and choosing the truncation value (kgnd) that yields the best overall verification statistics. Second, by reconstructing the entire spatial field with another truncation value, ksat. In both cases, the optimization is done on the basis of the entire data set; that is, the ‘best’ parameter depends on what works best on average both in data poor regions (e.g. West Antarctica) and data rich regions (e.g. East Antarctica and the Peninsula). The obvious risk here is that too high a truncation value will be used for West Antarctica. There is rather good evidence to be found in the Supplementary Material in O’Donnell that this is exactly what has happened. The choice of kgnd that yields the best agreement with the iridge calculations (which, remember, is already known to create problems) happens to be kgnd = 7, and it just so happens that this yields the minimum trends. In fact, O’Donnell et al. show in a table in their Supplementary Material that the mean trend for West Antarctica for smaller values of kgnd is more than twice (~0.2 °C/decade) what it is for their ‘optimum’ estimate of kgnd = 7 (~0.07°C/decade). Indeed, using any value lower than the one they choose to rely on largely erases any difference between their results and Steig et al., 2009. This simple fact — illustrated in the figure above (trends in °C/decade for 1957-2006) — has been notably absent in the commentaries that O’Donnell and coauthors have made about their paper.

Third, the way that O’Donnell et al. actually do the cross-validation to optimize ksat is itself pretty dodgy. Rather than using split calibrations (that is, comparing early period with late period statistics), they one-by-one withhold each weather station time series over the entire length of the record. To see the problem with this, consider what happens if you withhold the South Pole station record, which is complete for the entire time period, and then repeat the regressions to find the best truncation value for South Pole. For the period 1982-2006, when there are satellite data available for (and highly correlated with the station at) South Pole, the optimal number will be much higher (data richness) than during the pre-satellite era (data poor). The number that gets used will be an underfitting for the pre-satellite era and an overfitting for the satellite era. Note that ksat is actually the number of EOFs that get retained; since one needs many more of these to reconstruct the Peninsula properly, it is inevitable that they’ll wind up with more retained EOFs than we did; that doesn’t mean this is the right number for West or East Antarctica. O’Donnell et al. do report split calibration statistics as well, but this is not how they choose their optimal values.

Does all of this mean that I think O’Donnell’s results are all wrong? Certainly not. I think that they are right to have retained more EOF patterns than we did, though the main impact of this is only in capturing the strong Peninsula warming.*** It is also quite likely that O’Donnell et al.’s results are more accurate than ours for the satellite era, during which most of the problems I have discussed above are less likely to arise. Although their results show much smaller trends, they agree well with the spatial patterns in weather forecast reanalysis data products (NCEP2, ERA-40) during the satellite era. This is a nice, largely independent validation of those products, and suggests that it is okay to use those products — which include detailed information on atmospheric circulation changes, for example — for investigating the causes of the temperature trends. This is something that quite a few of us have been working on, but there has always been the nagging problem that we don’t really know how much we can trust NCEP and ERA products at high southern latitudes. O’Donnell et al. should certainly be cited in support of such work.

In summary, even if their results are taken at face value, O’Donnell et al. 2010 doesn’t change any of the conclusions reached in Steig et al. In West Antarctica where there is disagreement, Steig et al, 2009 is in better agreement with independent data, and O’Donnell et al.’s results appear to be adversely affected by using procedures known to underestimate trends. Thus while their results may represent an improved estimate for the trends in data rich regions — East Antarctica and the Peninsula — it is virtually certain that they are an underestimate for West Antarctica. This probably means going back to the drawing board to write up another paper, taking into account those suggestions of O’Donnell et al. that are valid, but hopefully avoiding their mistakes.

*Contrary to what Ryan O’Donnell has claimed, Doran et al. (2006) reported warming in Ellsworth Land (between WAIS Divide and the Peninsula) only in winter, with cooling in the annual mean. It is worth noting that Doran’s work has previously been misrepresented, though in the opposite way!

**There is, however, completely independent data from the WAIS Divide borehole, showing that this site has warmed by the same amount indicated by the Byrd weather station data — about 1°C since 1958. This is unpublished data, but the results were presented in an AGU talk and in the published abstract.

*** Peninsula warming was not the question we were addressing in our paper, as we made very clear in the text. We chose fewer EOFs based on our previous work (Schneider et al., 2004) showing that this sufficiently captures both East and West Antarctica.) Although retaining fewer EOFs reduces the spatial details, it is a conservative choice for estimating large-scale trends in both West and East Antarctica. See also our discussion on overfitting.

134 Responses to “West Antarctica: still warming”

  1. 51
    Hank Roberts says:

    TTTM, the papers are easy to find. You know how to do it.

    For anyone who’s never learned, here’s the easy way (the middling hard way is to email the corresponding author and ask for a copy, they’re allowed to send personal copies by most publishers’ agreements):

    Paste the cite into Scholar’s search box,
    [at this point note whether other papers have cited that paper]
    click the ‘all … versions’ link,
    look for a PDF or HTML.

    For the two discussed here, that finds among other copies:

    Cited by 92[PDF] from View as HTML
    Cited by 1View as HTML

  2. 52
    Hank Roberts says:

    arrrrgh. The blog software has edited the “cited by” and “view as” links I tried to post so as to break them — it appears they now point back to this thread. Sorry about that. If you find links with those words on them with a Scholar search they will work.

  3. 53
    Ray Ladbury says:

    Eric, I think it’s much easier to remain civil when both positions are evidence/reality based. When one side has all the evidence, the only option open to the other side is to cast aspersions on how the evidence was gathered and by association, the gatherers.

    I think that this serves as a great example of “normal” science. It is not that the participants are dispassionate automatons. They will argue their positions passionately, but the positions must be based on evidence.
    However, even more than being “right” the ultimate goal is to understand the phenomena under study.

    That said, I’d praise both sides for sticking to the evidence.

  4. 54
    Jim Steele says:

    For Rob #48 “it’s not hard to imagine that increased GHG concentrations will increase radiation to space, and thus cool down the area inside the vortex during the duration of winter months.”

    Rob it is actually very hard for me to imagine your scenario especially because it completely contradicts the whole CO2-warming theory.

    [Response: Actually not. It’s often forgotten that infrared opacity is only half of the story of how greenhouse gases affect the temperature of atmospheres and the surface. The other (and equally important) half is vertical temperature structure, which determines the energy flow. When the ground is much colder than some part of the atmosphere, it is theoretically possible for increased CO2 — or any other greenhouse gas — to cool the atmosphere while warming the surface. This happens because when the surface is very cold, there isn’t much upwelling IR to absorb, but increasing CO2 increases the IR cooling, both to space and to the ground. I’m not saying that the Antarctic winter surface is actually cold enough to be in this regime — I haven’t run the numbers — but radiative transfer is a very versatile tool, and can give rise to a surprising variety of phenomena. By the way, back when I was first teaching myself about radiative transfer, I published an example showing how increased greenhouse gases can cool at atmosphere. That’s in my JAS “Radiator Fins” paper, available through my publications site. –raypierre]

    Vortices on other planets such as Venus are ever changing and completely dynamical. Also compare the vortex in the Arctic which is more broken up by Rossby waves and thus leaving the Arctic winters much warmer than the Antarctic winters. Steig’s paper as well as others argue that a train of Rossby Waves originating in the Pacific near New Zealand are bringing warmth into the west Antarctic sector. I think that is likely very true. However those waves if anything would disrupt and weaken the vortex, and then more likely increase temperatures. So I do not see it as reasonable explanation for the significant cooling of the south pole in the winter half of the year. There have been trends noted with the time of break up of the vortex and ozone, but that is mostly a spring phenomenon and does little to explain the winter cooling trend. I was hoping Eric had some greater insight but he seems unable to explain that cooling trend either.

    Sometimes when your main tool is a hammer the whole world is nail. I just don’t see a reliable CO2 connection to the cooling. It reminds me of how despite Trenberth 1999 concluding. ““With higher average temperatures in winter expected, more precipitation is likely to fall in the form of rain rather than snow”, yet recently everyone in the media and some scientists are now trying to connect CO2 to recent increased snow. I suppose that is a normal reaction to defend an accepted theory, but reality suggests looking for an additional tool of analysis.

  5. 55
    RichardC says:

    24 Rob wonders, “If the temperature reconstruction from before 1980 for all of West Antarctica is based on the record of a single station”

    Is this true? Byrd is the only West Antarctica station prior to 1980? I can’t believe that.

    [Response: There may be a scattered point or two before then elsewhere, but I don’t think so, if memory serves. But you can easily look this up on the BAS web site.

  6. 56
    Jim Steele says:

    raypierre said ” it is theoretically possible for increased CO2 — or any other greenhouse gas — to cool the atmosphere while warming the surface.”

    But that is is exactly my point. The air mass ~500-1500m above the surface of the southpole is downwelling IR to the surface as well as to space. Agreed. The downwelling IR is exactly what maintains the steady 6 month winter temperatures that ony vary by about 2 degrees all season but that would otherwise drop by 1-2 degrees/day! – due to outgoing IR from the surface. Increased CO2 in that ~500-1500m air mass then should increase downwelling IR and thus contribute to surface warming. Yet the southpole surface temperature is significantly cooling in the winter half year.

  7. 57
    Rob says:

    @Jim(#54) “Rob it is actually very hard for me to imagine your scenario especially because it completely contradicts the whole CO2-warming theory.”

    You are right Jim. I realized this after I posted. ‘raypierre’s reply is of course correct in general, but a temperature profile where the stratosphere would be warmer than the upper troposphere is indeed ‘hard to imagine’, especially in the Antarctic polar vortex.

    I’ll think a bit more about other effects, but so far I’m with Eric. I do not know what could cause a cooling of the South Pole in winter. What do you think could cause it ?

  8. 58
    Rob says:

    Richard, I felt the same thing you do when I posted my response.
    Until now, I still feel that the Byrd station data is a thin line to walk to draw conclusions of ‘significant’ warming in West Antarctica over the past 50 years, especially since previous papers (based on 30 years of satellite data) reported a mild cooling trend.
    Still, please read Eric’s reply very carefully, since he put a lot of information in there, which ultimately convinced me that West Antarctica is warming, although I’m not so sure that the uncertainty margin (especially for the period before 1980) is accurate.

    Also, please understand that O’Donnell’s team is in direct competition with Eric’s team, and for me as an outsider, that tells me that if there was something fishy going on that O’Donnell would have found it. However, the result of both Eric’s and O’Donnell’s papers is consistent, and both studies are again consistent with more recent observations : West Antarctica is indeed warming.

    It would actually be strange if any one of these researchers would conclude otherwise, since many other observations (such as glacier retreat and speed-up and ocean temperature analysis) show the same pattern, warming starting at the Antarctic Peninsula, and working it’s way towards the interior.

  9. 59
    sHx says:

    It seems Ryan O’Donnell disagrees with Eric Steig.

    [Response: Gee, I’m so surprised. Ryan knows full well (as does Jeff) is welcome to comment here is he avoid the kind of inflammatory language that some of his coauthors use.–eric]

  10. 60
    Jim Steele says:

    Rob #57

    Like Eric I really can’t say what are the causal factors for the southpole cooling. The south pole cooling is curious especially with such dry air, it should be very sensitive to any forcings. The dynamics of the Antarctic Circumpolar Wave certainly deserve more attentions and I believe would mesh well with Eric’s west Antarctica work.

    Comparing weather stations does not gives us a long enough picture. I believe Jones did not even include Antarctica data in generating global trends (but maybe he used the Orcada data?). Anyways the Chinese and Australians did several joint ice core drillings to use ice core date from which Zhang 2002 wrote a paper “Temperature Variation and its Driving Forces over Antarctica”. Those cores give a picture of great variations.

    In the past 50 years within the Lambert Glacier basin had temperatures rising in the eastern part, while cores on the Mizuho plateau, Kamp Land and western Lambert Glacial Basin show cooling or no trend in the past 50 years.
    In contrast from 1850-1950 the Mizuho cores show warming, as do cores from Hercules Neve (just south of the western Ross Sea), Law Dome While the four sites, Darlinger Dome, Siple, T340, (in the Peninsula region) and DT001(180 degrees from the peninsula) all show cooling trends from 1850-1950. But the peninsula has been one of the most rapidly warming areas recently.

    Zhang suggests that the Antarctic Circumpolar Wave shifts weather patterns along the coast areas by ~90 degrees on ~150 year time spans. While on scales of ~50 years large scale terrain effects such as major drainage basins may be the bigger climate factor.

    However the ACW may have little to directly do with the more inland and southpole trends. The southpole cooling trend may simply reflect the same general cooling trend seen in the Arctic for the past ~9000 years but just insulated from dynamical ocean and wind forcings.

  11. 61
    Hank Roberts says:


    “While most of the Earth warmed rapidly during recent decades, surface temperatures decreased significantly over most of Antarctica. This cooling is consistent with circulation changes associated with a shift in the Southern Annular Mode (SAM). It has been suggested that both Antarctic ozone depletion and increasing greenhouses gases have contributed to these trends.

    We show that a climate model including the stratosphere and both composition changes reproduces the vertical structure and seasonality of observed trends. We find that the two factors have had comparable surface impacts over recent decades, though ozone dominates above the middle troposphere.

    Projected impacts of the two factors on circulation over the next fifty years oppose one another, resulting in minimal trends.

    In contrast, their effects on surface climate reinforce one another, causing a departure from the SAM pattern and a turnabout in Antarctic temperatures, which rise more rapidly than elsewhere in the Southern Hemisphere.”

  12. 62
    ThinkingScientist says:

    RE: Vernon at 42 says:

    “Why are responses from one of the co-authors not being posted? That seems counter productive.”

    Two of the authors RyanO and JeffID are posting at and

    Hey Eric – why don’t you go and debate this at At least then we will all know the comments are not being censored.[edit for insulting remarks].

    [Response:Know what? I have a day job. And those guys know perfectly well I do not read those sites without a good reason to, and telling me I have ‘explaining to do’ doesn’t rise to that level. If they have scientific points to make, they should make them here.–eric]

  13. 63
    Chris Colose says:

    Did someone send an invitation to the loons? Looks like the bore hole will be opening up

    [Response: No, they invited themselves. as usual.–Jim]

  14. 64
    Marco says:

    Eric, I guess civility has been thrown out of the window. To quote O’Donnell talking about you:
    “There are not enough vulgar words in the English language to properly articulate my disgust at his blatant dishonesty and duplicity.”


    “Fool me once, shame on you. But twice isn’t going to happen, bud.”

    So forget about communicating with him, he thinks you are blatantly dishonest.

    [Response: Sigh…]

  15. 65
    grypo says:

    So the biggest complaint is that Steig intentionally forced ODonnell, in a review comment, to use a result that he could later criticize by saying it underestimated the trend. But is it the case that both underestimated the trend and that ODonnell’s use of station data had pitfalls either way, it’s just that Steig’s suggestion was the “most likely”? Not sure what the answer is here. This appears to be another example of dragging scientific arguments out into the open to make a scientist look bad (Oh how surprising!) But I would like at least the scientific complaint to be addressed, if possible.

    [Response: I haven’t bothered to go read what is evidently being written about me, but if this is an accurate description um.. you’re kidding right? I’m now being blamed for their writing a lousy paper? Really? If this weren’t so sad it would be hilarious!–eric]

  16. 66
    andrew adams says:

    [Response: If said co-author could stick to the point at hand, said co-author would get listened to.–eric]

    Given you have criticised their paper surely it is better to allow the co-authors’ comments to stand out of courtesy and fairness, even if you think they are avoiding the point. By moving Jeff Id’s response to the Bore Hole it just makes it look to outsiders as though you can’t take criticism.
    I have RC in the past against some of the the flack it gets elsewhere but this makes it more difficult.

    [Response: The only thing that was moved to the Borehole was off topic snark referring to Mike Mann’s earlier work. Jeff knows full well that any on-topic scientific comments will be posted here if he writes them. I’ve seen nothing come through since then, so this is a complete fabrication.

    P.S. I’m not really interested in more unsolicited advice on how to respond to someone calling me ‘duplicitous’.–eric]

  17. 67
    Dave Walker says:

    Non scientist here again.

    I have read the piece here in RC regarding Antartic temperatures and also read the pice by a Jeff Id. I do not know who these people are but there seems to be a real disagreement about scientific method and who said what – but its is beyond my understanding.

    Mr Id seems somewhat agrieved on a number of points that he feels a very important. One is whether a reviewer of his paper was actually one of the people who’s methods were being challenged (is this correct, is it “normal” practice or does he have a point?). Secondly, he takes issue with processes and statements and the way he has/is being treated.

    Any chance that someone could clarify these points for me?

    [Response: It would be entirely normal for an editor to send a paper criticizing someone’s work to that person, for their opinion. You just wouldn’t want that opinion to be the deciding factor, which is why normally you’d get several other reviewers; this is presumably the case here. Reviews, however, are usually confidential and anonymous. As for our ‘treatment’ of Jeff Condon, he hasn’t written anything here lately so I really don’t have any idea what he is talking about.–eric]

  18. 68
    toto says:

    eric: I’m now being blamed for their writing a lousy paper?

    Apparently he’s claiming that you recommended them to drop the TTLS method for the iridge method in your review, then criticized them for doing just that in your RC post.

    I smell a misunderstanding, and I would suggest actually reading hhis AirVent post and then contact him directly.

    [Response: This is the most bizarre thing I’ve heard yet. Is there really anything else to say? — eric]

  19. 69
    MapleLeaf says:

    Let me see, the title of the recent posts at CA are:



    Now compare those with the title of this post– telling is it not? And McIntyre has just attended a “reconciliation” workshop in Lisbon….well that was apparently just some window dressing on his part…

    Accusations of ‘duplicity’ McIntyre is laughable, seriously– he must be deluded. Moreover, it very clearly demonstrates that Stephen McIntyre and JeffId have no interest whatsoever in engaging in good faith. This is a power game for them, an attempt to feed fodder to the “skeptics” and another attempt to make a mountain out of a molehill by Stephen McIntyre– times are hard, their “reach” declined rapidly and has now plateaued after the SwiftHack debacle. So they are clearly trying to fabricate some “denialist chum”.

    The CA gang are trying to bait Steig into a food fight and are trolling for ammunition to use against Steig– don’t fall for it Eric. You and O’Donnell can publish side-by-side comments in the journal which speak to these issues. That is the appropriate forum, not internet blogs.

    If people do insist on a blog, then they need to go to a neutral venue and have it out– might I suggest Bart Verheggen’s, and that rule for engagement be spelled out clearly.

  20. 70
    PaulM says:

    The main effect of including more EOFs is not so much that it captures the peninsula warming, but that it avoids smearing this localised warming over nearby regions of the continent.

    [Response: And your evidence for this claim, precisely?–eric]

  21. 71
    Sean Houlihane says:

    In the interests of trying to reach some common ground, how about a demonstration of the sensitivity to modified trends at some selected stations used for this analysis? I have found it very instructive to see how some methods can give what are superficially bizarre results when applied to data sets with known trends. It’s all very well claiming that one method is better than another, but please show this with some comparative data sets.

  22. 72
    Hank Roberts says:

    Another avalanche of mail and complaints?
    I’m shocked ….
    Wait, is there a cyclical pattern to this stuff?

  23. 73
    dhogaza says:

    And McIntyre has just attended a “reconciliation” workshop in Lisbon….well that was apparently just some window dressing on his part…

    Well, Mapleleaf, as you know, “reconciliation” in the denialist’s handbook is defined as “surrender or we’ll take no prisoners”. And, of course, if you don’t show up for your pre-ordained surrender ceremony you’ll be lied about by Pearce at the Guardian and smeared all over the blogosphere …

    P.S. I’m not really interested in more unsolicited advice on how to respond to someone calling me ‘duplicitous’.–eric

    Probably a good thing, because my suggestions would probably be unpleasant for the person acting so unprofessionally towards you …

  24. 74
    TerryMN says:

    @MapleLeaf, dhogaza:

    McIntyre didn’t write either post – the lead author, Ryan O’Donnell did.

  25. 75
    grypo says:

    Eric said – “you’re kidding right?”

    No afraid not. This looks like a full on blitz. You are being accused of gaming the system by using your review comments to either a) hope ODonnell refuses and gets rejected or b) even if he publishes, you have a way to easily refute his paper.

  26. 76
    MapleLeaf says:


    Point taken about the author of the posts. I am still disturbed that Mcintyre would publish such posts, and permit the vitriolic titles and content. It is McIntyre’s blog (i.e., he approves which posts are published) and he was also a co-author on the O’donnell paper. How does McIntyre allowing those posts work towards “reconciliation”? Answer, it does not, not by any stretch of the imagination.

    McIntyre now appears to be doing something similar to Watts does– offering a podium (i.e., his blog) from which people can attack the scientists.

    This turn of character by O’Donnell is troubling. Initially he seems very reasonable, sincere and amicable. What we are seeing now is very unpleasant and uncalled for. I have to wonder whether his initial tone was all a facade, because this unpleasant transition has been very rapid.

    They have run out of steam on the Mann et al’s HS and ClimateGate, now they have turned their attention to Steig and are trying to game Eric into a street fight to try and fabricate a new “controversy”.

  27. 77
    dhogaza says:

    McIntyre didn’t write either post – the lead author, Ryan O’Donnell did.

    Yes, but he posted it. If he were truly moved by the spirit of reconciliation, he’d’ve asked Ryan O’Donnell to remove the personal attacks before allowing the post.

    Don’t worry, though, I’m not surprised or shocked or disillusioned or nuthin’ like that.

  28. 78
    Septic Matthew says:

    54, raypierre in response: It’s often forgotten that infrared opacity is only half of the story of how greenhouse gases affect the temperature of atmospheres and the surface. The other (and equally important) half is vertical temperature structure, which determines the energy flow. … .

    A timely reminder. Thank you.

  29. 79
    Hank Roberts says:

    > increased GHG concentrations will increase radiation to space, and thus
    > cool down the area inside the vortex during the duration of winter months.

    Worth remembering, ozone in the stratosphere is a greenhouse gas, and ozone depletion varies with temperature. (2010) (1998)

  30. 80
    Didactylos says:

    It took me a while to get the key points here. But I think I have, now.

    Eric said they should address the iridge underestimation issue. They didn’t. Eric said they had failed to address the issue. They cried.

    And they complain about space constraints? The internet is big. It has space for all the supplemental information they can come up with.

    Their inability to understand about infilling, though, just made me laugh.

    For extra comedy value, they seem extraordinarily pleased about how easy it is to exactly reproduce their results, while being oblivious to how opaque it is.

  31. 81
    Hank Roberts says:

    And, in draft, a survey article with a lot of info I didn’t know:

  32. 82


    O’Donnell and his coauthors argue that the choice of iridge (instead of TTLS) in response to comments from a reviewer of the paper. This, at least, seems to be a somewhat weak point upon which to critique their approach if their originally submitted work relied solely on TTLS.

    [Response: How can I put this succinctly? How about this; I have pointed out the facts of the matter to O’Donnell et al. They have not changed what they have written. They are therefore now lying to their readers. It’s actually about that simple. –eric]

  33. 83
    Ray Ladbury says:

    Sigh! I guess I spoke too soon about a post that stuck to the science. But I guess since ad hominem is all the denialists have, they feel they have to use it…or are they doing it just to keep in practice? Really, publishing such idiocy on CA is just dumb. If they are correct, their method will eventually prevail. If they are wrong, then there are worse things that being wrong–unlike most denialists, they at least published. Instead they feel the need to make it personal AND public. How unprofessional.

  34. 84
    BPW says:

    Did my questions get snipped/moderated and if so, why? I should have kept a copy of my questions in case they failed to make it through. They were perfectly legitimate questions giving you a chance to explain this issue from your side rather than letting folks like myself simply take O’Donnell at his word that you acted in an unprofessional and potentially dishonest manner. Simply asking you to clarify your position.

    1) Were you, as he states, one of the referees on his paper?

    2) If so, do you think that the conflict of interest that would seem to come from that being the case is meaningful and if not, why not?

    3) Did you, as part of your review, ask that they change their method only to later criticize that method?

    Like it or not, if you don’t directly address these accusations, the impression lay people are left with is that the whole thing smacks of dishonest use of peer review.

    I am not qualified to suss out the science, but i am qualified to understand O’Donnell’s accusations. I am willing to accept that there is something lost and that he is misrepresenting the situation, but if you waive away these type of questions and quash those who try to ask, what are we left to think?

    [Response: Perhaps you should try thinking, instead of asking me what to think. Let me turn this question around on you: why do you take O’Donnell at his word? And now he’s my word: His allegations have no basis in fact. Now you have my word against his. Now try thinking,-eric]

  35. 85
    Michael says:


    You don’t understand at all.

    Think of the traffic! The number of comments!

    Universal Rule of ‘Skeptic'(AKA Climate P0rn) Blogs No. 543 – the louder the conversation, the smarter it is.

  36. 86
    Hank Roberts says:

    > Think of the traffic! The number of comments!
    > Universal Rule

    But think of what the journal’s editors established by bringing the original exchange out of the blogs into the journal:

    “O’Donnell et al. is the peer-reviewed outcome of a series of blog posts …. As one would expect of a peer-reviewed paper, those obviously unsupportable claims found in the original blog posts are absent, and in my view O’Donnell et al. is a perfectly acceptable addition to the literature.”

    So — next move, try to take the science away from the journal editors AGAIN?

    I hope the journal editors take this issue and, again, make a publication out of the issue. They will get scrutinized. I hope they’re up to it.

    Someone should invite them into the conversation — or urge them to invite the parties into a conversation at their place, wherever that is.

  37. 87
    Eric Adler says:

    Check out WUWT

    Watts claims that Eric’s reply, to Jeff Id’s comment number 18, was a threat to send his post to the borehole. Their quote was actually a reply to post number 10. This was reply to a comment by J, that quoted Marohasy.

    In fact your reply to Jeff Id was polite and scientific. WUWT?

    It seems that so far, I was the only poster to check out Anthony’s claim, because it seemed wrong, and it was.

  38. 88
  39. 89
    dhogaza says:

    They were perfectly legitimate questions giving you a chance to explain this issue from your side rather than letting folks like myself simply take O’Donnell at his word that you acted in an unprofessional and potentially dishonest manner

    Eric beat me to it, by why would you take O’Donnell at his word???

    Why must Eric counter it before you question whether or not his word is trustworthy?

    And … why haven’t you quit beating your wife? I don’t have the words to describe how despicable your actions are.

    And my word is equally as trustworthy as O’Donnell’s.

    So, dude, answer my question. Why haven’t you quit?

    See the problem, now?

    (for the record, I think you’re probably actually a promoter who will get O’Donnell’s and Steig’s wives on HBO pay-for-view in a cage fight, because, you know, we can all make shit up.)

  40. 90
    dhogaza says:


    So — next move, try to take the science away from the journal editors AGAIN?

    At this point, I think it’s clear that they’re trying to take the science away from the journal editors.

    Rather, they’re pissing on Eric’s ethics and professionalism (in an incredibly unprofessional way, given that they want to be let into the fold), and they’re blaming Eric for whatever errors they may’ve made, because “the peer review process made us introduce errors!”.


  41. 91
    BPW says:

    Eric @83,

    I DON’T take him at his word. Which is why I asked. But you did not respond to the question. Telling me to think is not addressing the issue, nor answering the question. Nor did I ask you what you think aside from the conflict of interest issue, and on that point I would actually appreciate your opinion on the subject. Especially with regards to–allegedly–making important suggestions, which result in changes, which you later critique as being incorrect.

    As for your statement that his accusations are bogus? OK, I am willing to listen. But since O’Donnell’s accusations are fairly serious, and detailed, I would be more convinced if you had more of a response than “his allegations have no basis in fact” supported by no facts.

    I think that your–alleged–part in the review has the potential to be perceived as a conflict of interest. Others do as well. Tell me (us) why we should not believe it to be true.

    I follow these blogs as a hobby. An interest. I am not biased against you even a little. I make my living in the world of science despite not being a scientist myself. I am not anti you, or science. But O’Donnell does bring up points which seem, at face value, valid, and supported. I think you should answer these accusations lest they be believed by people like myself as being the truth by default.

    This story breathes serious life into the concept that peer review is tainted. O’Donnell has provided a strong case which does not seem implausible. Tell me (us) (people) your side.

    To be fair, and in conclusion, you owe me nothing. Tell me to pound sand if you like. It’s your right. But this situation has the potential to taint your message, and the perception of the science as a whole, for the curious like myself.

    [Response: I’ll have a post later today addressing these points. Forgive me for being annoyed with you for assuming it might actually be true that I am a deceptive duplicitous idiot.–eric]

  42. 92
    Marco says:

    Eric (Steig): I think this issue can be resolved quite easily, you could just publish your reviewer comments so everyone can read what you indicated *in context*. You could even add an explanation how O’Donnell et al did or did not implement your comments in the manuscript. All that is possible without snark.
    Two advantages:
    1. No chance for cherry-picking (although there still may be discussions on what you meant and how they interpreted the comments)
    2. Another nail in the coffin (ha!) of “when we skeptics ask nice questions, alarmist can only react with abuse”
    I recommend doing this without reading what O’Donnell and Patrick Condon wrote exactly, although you already have had some snippets. Forget them. Make it factual and to the point.

  43. 93

    This is evidently higher-order ad hominem. They can’t argue with the data, so what remains?

    Right. Attack the man. If you lack the skill, then you’re left with brute force.

    Highly disappointing. (Again.)

  44. 94
    AMac says:

    Yesterday, O’Donnell presented a set of images that suggest that the main algorithm used in Steig et al (2009) yields a picture of Antarctic temperatures that is sensitive to the addition of a synthetic +0.2 C or -0.2 C trend to the weather stations on the Peninsula. This is an intuitive finding. However, O’Donnell’s images show that the algorithm is insensitive to addition of such trends to the only two weather stations on the West Antarctic Peninsula (Russkaya and Byrd).

    If true, this would be a very surprising outcome. Do you think this portrayal is accurate? If it is, what’s the likely explanation?

    [Response: Yes, it would be surprising. It is hard to follow their line of argument amidst all the allegations and other crap though.–eric]

  45. 95
    Pat says:

    Hank 89
    “the peer review process made us introduce errors!”.

    Do you have a link for that quote?

  46. 96
    Nick Dearth says:

    BPW says – “Like it or not, if you don’t directly address these accusations, the impression lay people are left with is that the whole thing smacks of dishonest use of peer review.”

    As a layperson might I suggest you speak only for yourself or explicitly state exactly who you represent, because it certainly isn’t me. The impression I am left with is not the same as yours, apparently.

  47. 97
    One Anonymous Bloke says:

    BPW 91. I’m sure Eric will express this much better than I can, but my impression is that if science isn’t an argument, it won’t work properly. O’Donnel et al were advised to change something in their paper during the peer review process. They didn’t change it. The reviewer who made the suggestion thinks that undermines their findings (well duh!), and has explained why. This doesn’t show that the peer-review process is compromised, it shows that it’s working. Now the O’Donnel paper has been published, we laypeople can gauge its skill by the number of cites it receives in the years to come.

    As an aside, Fourier and Arrhenius were the pioneering outliers who risked their reputations on AGW; it took one hundred years (give or take) for the truth of their findings to be demonstrated.

    [Response: This is the first rational response I’ve seen yet. Thank you.–eric]

  48. 98
    Hank Roberts says:

    Without knowing what _all_ the reviewers said to the editors, you don’t know what the editors relied on in getting the paper into shape to publish.

    Please consider this from the point of view of the journal’s editors, and of the other reviewers–whoever they were, and whatever they said.

    The editors had to weigh information we outsiders don’t have. The authors and any individual reviewer likely don’t have everything the editors had to consider.

    This fuss over this paper is one piece in a bigger game – taking peer review out of the hands of the journal editors and individual reviers.

    But if there’s any real challenge to the process, the editors ought to get first crack at it.

    Have the journal’s editors already had time to consider the claims now being blogged?

  49. 99
    dhogaza says:


    They were perfectly legitimate questions giving you a chance to explain this issue from your side rather than letting folks like myself simply take O’Donnell at his word

    Then later claims:

    I DON’T take him at his word. Which is why I asked.

    Fail. If not in fact then in clear, unambiguous use of language.

  50. 100
    grypo says:

    I’ve attempted to dissect what seem to be the important points from the reviews and following melee.
    Please have a look.