AR4 Models and the Ross Sea

I noticed something interesting in AR4 about Antarctic models, that no one mentioned in the initial commentary on Steig et al.

When Steig et al 2009 came out, commenters had some fun teasing the clergy over at realclimate over Spencer Weart’s article the prior year. Pielke Jr Lucia CA

Speaking for myself, I went to some pains to remind those readers who were piling on to this issue that there were sui generis aspects to Antarctica modeling and, even if models missed some detail of Antarctic behavior, that certainly didn’t imply to me that models were WRONG(!), a conclusion that some readers wanted to jump to. Having said that, I agree with Lucia’s comments below:

It may well be that the Antarctic is doing precisely what models predicted. But in that case, it would have been better if Weart had written a more nuanced article that explained more precisely what they predicted, in what way the predictions were consistent or inconsistent with data as thought to exist back in Feb 2008. He could also have discussed the uncertainty in data which arises from poor spatial coverage. He could have said the models predict warming– but so slowly it would be difficult to detect. He could have said many things.

Had this more nuanced article been written, RC could now write an article that explained how the discovering that parts of the continent formerly thought to be cooling are actually warming, and told us if the new knowledge about the warming compares to model predictions.
But, as it stands, the impression given by Weart article at RC published in 2008 was this:
a) Denialists say Antarctica has been cooling.
b) Scientists believed that Antarctica has been cooling.
c) Models predicted this cooling and had done so for decades.
Now, we learn it’s warming.

I’ve no doubt we will be told the warming is also consistent with model. But, if both warming and cooling both said to be consistent, people are going to wonder what modelers mean by “consistent”.

Let’s review the press releases accompanying Steig:

Antarctica during the last 50 years, with the dark red showing the area that has warmed the most. url

(Credit: Image courtesy of University of Washington)

Or at RC:

The paper shows that Antarctica has been warming for the last 50 years, and that it has been warming especially in West Antarctica (see the figure)

In each case, note that the supposed locus of observed warming in West Antarctica includes the Ross Ice Shelf (not labelled in either cartoon, but it’s the notch to the right of the legend “West Antarctica” in the above diagram, where Steig, Mann et al discovered previously unknown warming.

Curiously, AR4 had opined on model predictions for the Ross Ice Shelf in particular, noting that models predicted a local minimum in expected warming in this area:

In 20th- and 21st-century simulations, antarctic sea ice cover is projected to decrease more slowly than in the Arctic (Figures 10.13c,d and 10.14), particularly in the vicinity of the Ross Sea where most models predict a local minimum in surface warming.

I wonder what would happen if one RegEM’ed the models.


  1. Carrick
    Posted Mar 30, 2009 at 10:24 AM | Permalink

    I wonder what would happen if one RegEM’ed the models.
    Me too. Take the surface map of stations, read the outputs from a given climate model at those stations, treat as data & RegEM it.

    I wonder how accurately this would reproduce the actually model results?

  2. Posted Mar 30, 2009 at 10:49 AM | Permalink

    For those who want to look it up, the chapter and verse of the AR4 gospel is chapter 10, page 770.
    Sorry to say this again but: the data show that the region of strongest warming is the peninsula, not West Antarctica, with warming five times as great as claimed by Steig et al, who are just completely wrong. The main part of Antarctica has not warmed at all (AR4 pages 814-816). Steig et al get their false result by spreading the peninsular warming thinly over a wider area.

    • Steve McIntyre
      Posted Mar 30, 2009 at 11:08 AM | Permalink

      Re: PaulM (#2), just because Steig et al differ from a statement in AR4 doesn’t mean that they are “completely wrong”. Steig is free to disagree with AR4 as we are. I’m inclined to agree that Steig are spreading the warming, but this is something that requires more than assertion – many posts here and elsewhere have been spent deconstructing this issue.

  3. Posted Mar 30, 2009 at 11:09 AM | Permalink

    As I’ve mentioned before numerous times. Even if a model “predicts” certain climate behaviors, there is no way to tell if they predicted for the right reasons. And we also seem to be reacting to generalities. Maybe it is generally warmer where models predict, but the bottom line is there is no evidence than anything is happening “globally” in any one direction. This is either a failure of models, or a “jumping to conclusions” by scientists.

  4. Luis Dias
    Posted Mar 30, 2009 at 11:39 AM | Permalink

    First off, I understand the motive of this post and I agree with it. Another curious anecdote.

    But one should not do this type of cherry picking. If one is to do this kind of analysis, then one should do it a la Koutsoyannis (?), but for every region of the world.

    It’s easy to say that the models are regionally inconsistent here and there. It’s harder to say that they are overall more inconsistent than white noise.

    Not that one shouldn’t look at it. But be careful before pointing out that others were too sure of themselves without shooting in your foot first.

    (The alternative is to write a mild hit-n-run post as this one without developing the thing. Kinda cheap shot really…)

    • Steve McIntyre
      Posted Mar 30, 2009 at 12:07 PM | Permalink

      Re: Luis Dias (#5),

      my preference would have been that Steig et al refer to the AR4 position on the matter rather than leave it for others to notice, as one can reasonably assume that Steig would be intimately familiar with AR4 statements.

      • MC
        Posted Mar 30, 2009 at 12:40 PM | Permalink

        Re: Steve McIntyre (#7), I would agree as AR4 should by its definition be an important reference as it does represent a review of many issues for climate change / global warming.
        With reference to Lucia’s bit in this post, since Antarctica is believed to be warming very slowly and that this is due to its geographic location on the Earth amongst other things, I wonder if it can be used as a control for all models (non-AGW models and AGW models). The difference between the two models may be less than the uncertainty in the Antarctic temperature trends. Just a thought.

  5. Posted Mar 30, 2009 at 12:00 PM | Permalink

    The excessive use of RED color in the image to indicate the level of warming is deceptive since it looks like it’s a heat wave that’s going on there rather than tiny differences. A narrower color range or a different color scheme would be better (blues maybe) as the human brain reads too much into an image (090121144049.jpg) like the one shown above of Antarctica.

    Perception is reality in most people’s minds. That image looks likes it’s the tropics down there…

    Images, damned lies and images.

    Just a thought.

  6. David L. Hagen
    Posted Mar 30, 2009 at 1:40 PM | Permalink

    Any chance geothermal warming of the surface (including active volcanoes)could be contributing to a small increase in surface temperature of west Antartica vs east Antartica, as seen by satellites vs air temperature thermometers.

    e.g. See: Scientists Find Active Volcano in Antarctica By KENNETH CHANG, NY Times, January 21, 2008

    Steve: No. I don’t want to waste bandwidth on this.

    • tty
      Posted Mar 30, 2009 at 3:41 PM | Permalink

      Re: David L. Hagen (#9),

      In brief, no. Volcanism and geothermal energy are too local and too weak to have any significant effect on surface temperatures. However they can significantly affect basal melting of the ice and thereby influence how fast it moves.

  7. Bruce
    Posted Mar 30, 2009 at 1:43 PM | Permalink

    “A major reason most of Antarctica was thought to be cooling is because of a hole in the Earth’s protective ozone layer that appears during the spring months in the Southern Hemisphere’s polar region. Steig noted that it is well established that the ozone hole has contributed to cooling in East Antarctica.”

    “and while some areas have been cooling for a long time ”

    I was quite sure they claimed that East Antarctica was “warming”. But here Steig says it was cooling.

    • AnonyMoose
      Posted Mar 31, 2009 at 6:37 PM | Permalink

      Re: Bruce (#11),

      … “and while some areas have been cooling for a long time ”

      I was quite sure they claimed that East Antarctica was “warming”. But here Steig says it was cooling.

      As was pointed out in earlier Steig discussion, Steig’s “warming” study went back to a starting point where it could claim the starting temperature was lower than it is now. Because its starting point is cooler, it can claim warming since that point 50 years ago no matter what happened during that time.

  8. Jim Steele
    Posted Mar 30, 2009 at 5:43 PM | Permalink

    Lucy Skywalker said
    ” (d) it’s polar so all fluctuations tend to be larger.”

    I know it is well established that climate fluctuates more at the poles relative to the equator. But why? What is the mechanism?

    • DeWitt Payne
      Posted Mar 30, 2009 at 9:31 PM | Permalink

      Re: Jim Steele (#12),

      …climate fluctuates more at the poles relative to the equator. But why?

      The simple answer is because it can. The mechanism is the much lower specific humidity and therefore lower heat capacity of the atmosphere at high latitudes and particularly near the poles. Central Antarctica is perhaps the driest place on the planet.

      • Posted Mar 31, 2009 at 2:29 AM | Permalink

        Re: DeWitt Payne (#14),
        climate fluctuates more at poles than at the Equator because of…

        much lower specific humidity and therefore lower heat capacity of the atmosphere at high latitudes

        I can’t see the connection, DeWitt, you always think that the deus ex machina of locale climate is radiation. Of course, it is not. There is little humidity at poles because it’s cold and not viceversa.
        But this is off topic…

        • DeWitt Payne
          Posted Apr 1, 2009 at 2:24 PM | Permalink

          Re: Paolo M. (#17),

          But I am talking about convection, or at least advection. A joule of extra heat in the tropics produces a small temperature change because the heat capacity of humid air is so high. Transfer that joule to high latitudes by air circulation where the heat capacity is lower and you get a much larger temperature change.

      • Jedwards
        Posted Mar 31, 2009 at 1:55 PM | Permalink

        Re: DeWitt Payne (#14), Don’t neglect the variation in insolation at the poles either. Having 24 hour sunlight during local “summer” vs no sunlight in local “winter” is much different than at the equator where its essentially 12-on/12-off no matter the season.

  9. Posted Mar 30, 2009 at 6:27 PM | Permalink

    A version of Steig’s Nature cover map with a color scale is at

  10. Posted Mar 30, 2009 at 9:43 PM | Permalink

    Thompson and Solomon’s Figure 3 shows pressure trends (1979-2000) which, as I interpret them, are consistent with colder temperatures over the Ross Sea, much of West Antarctica and the interior and warmer temperatures over the Peninsula.

    Those pressure change patterns indicate to me that the Antarctic interior and Western Antarctica should trend together when the dominant climate feature (Southern Annular Mode) changes.

    Thompson also noted evidence supporting their conjecture:

    At the surface, the Antarctic Peninsula
    has warmed by several K over the past several
    decades, while the interior of the Antarctic continent
    has exhibited weak cooling (10, 11). Ice
    shelves have retreated over the peninsula and
    sea-ice extent has decreased over the Bellingshausen
    Sea (12–14), while sea-ice concentration
    has increased and the length of the sea-ice
    season has increased over much of eastern Antarctica
    and the Ross Sea (14–16).Here, we
    offer evidence that illuminates the connections
    between these seemingly disparate trends.

    Contrast that with Steig’s abstract, which notes:

    regional changes in atmospheric circulation and associated changes in sea surface temperature and sea ice are required to explain the enhanced warming in West Antarctica.

    It’s hard for me to imagine what “regional changes in atmospheric circulation and associated SST” would be consistent with the large changes in geopotential height pattern shown in Thompson’s Figure 3.

  11. Jim Norvell
    Posted Mar 30, 2009 at 9:52 PM | Permalink

    In the recent reconstruction of Temps in Antartica did they adjust for altitude? A whole lot of the Eastern part is above 8 to 9000 feet. That must have some effect.

    Jim N

    • David L. Hagen
      Posted Mar 31, 2009 at 9:14 AM | Permalink

      Re: Jim Norvell (#17), Having lived at 6,000 ft and climbed to 14,000 ft, I endorse Jim’s comment on altitude being an important parameter controlling temperature. There is a strong difference in elevation between the plateau of East Antarctica at about 2,000 m to 4,000 m and West Antarctica which is almost all below 2000 m.See Antarctica at NASA Earth Observatory

      Using trends of changes (or “anomalies”) may ignore this difference.

      However, understanding how climate changes with altitude may be important in identifying why there is differing warming in West vs East Antarctica (if any). e.g., changing ocean currents vs changing Cosmic Rays and Ozone concentrations may impact West vs East Antarctica differently. cf David Smith’s #16 cite of Thompson & Solomon which shows strong changes in Ozone, vs Steig focusing on sea surface temperature.

  12. Posted Mar 31, 2009 at 12:24 PM | Permalink

    my liking would individual been that Steig et al touch to the AR4 status on the matter rather than departure it for others to observance, as one can moderately strike that Steig would be nearly beaten with AR4 statements.

    • bender
      Posted Apr 9, 2009 at 11:02 AM | Permalink

      Re: raj (#19), That’s called “appeal to authority”. The goal here is not to refute what Steig et al said, but to understand what they did and what the evidence is for their claims. This is PRECISELY what the IPCC’s task is – to review that literature and to critically evaulate the evidence. Would you prefer to have (A) 5AR appealing to the authority of the 4AR, or (B) 5AR being able to draw on some independent assessments of the new literature published between 4AR and 5AR?
      Full speed ahead.

  13. Nick Stokes
    Posted Mar 31, 2009 at 4:07 PM | Permalink

    I think this passage from the AR4 is being misinterpreted. They are talking about the melting of sea ice. So “vicinity of the Ross Sea” is not the Ross Sea itself, but the nearest part of the edge of the sea ice. And in the context, “surface warming” seems to refer to the ocean surface levels, which is not what Steig is measuring.

  14. Dirk
    Posted Apr 1, 2009 at 12:04 AM | Permalink

    West Antarctica is full of volcanoes.

  15. Geoff Sherrington
    Posted Apr 4, 2009 at 6:24 AM | Permalink

    Here is some temperature data from Mawson base which is about 67 deg S and 63 deg E, being almost opposite the Peninsula area. The figures have not,to my knowledge, been massaged very much. I’m keen to see how they compare with (say) GISS or HADCRU or whatever Dr Steig used for ground truth. I have Davis base also, some 650 km away, both bases being on the continental edge. There is very minor data infilling. Incidentally, for the overlap period 1969-2006, the correlation coefficient is 0.8364. The curve fitting is not justified but is added for pictorial effect. Note that 2008 is about the 8th coldest year in the last 45 at Davis. My 2007 and 2008 source for Mawson has ceased publishing on the Net.

  16. Posted Apr 4, 2009 at 5:05 PM | Permalink

    I’ve just completed a high order RegEM based on the satellite and surface station data. I’m tired from looking at it now but I found that covariance, used by RegEM to allocate trends across the continent doesn’t seem to care what the long term trend really is.

    RegEM really seems to be a complex blender of some sort.

  17. nevket240
    Posted Apr 6, 2009 at 12:18 AM | Permalink,25197,25295570-2703,00.html

    on topic, I think.


One Trackback

  1. […] McIntyre at Climate Audit has looked at heat maps of antarctic warming, and noted that the Ross Ice Shelf is at the center of the […]

%d bloggers like this: