Steig et al, revisited with UAH satellite data

From World Climate Report: Antarctic Temperature Trends

Almost exactly two years ago, a prominent paper became a media darling as it, according to the alarmist website Real Climate “appeared to reverse the ‘Antarctic cooling’ meme that has been a staple of disinformation efforts for a while now.”

The Nature paper, by Eric Steig and colleagues, made the cover on the January 22, 2009 issue.


Figure 1. Cover of January 22, 2009 issue of Nature magazine (left) showing the map of temperature trends across Antarctica as determined by the analysis of Steig et al. (right).

Despite Real Climate’s predictable take on the situation, many long-time students of Antarctic climate change (including usn’s here at WCR) yawned. It has been known for decades that there is a net warming in Antarctic surface temperature that began during the International Geophysical Year in 1957. However, what is also well known, is that the vast majority of the observed warming in Antarctica took place from the late 1950s through the early 1970s and that since then—during a period going on 40 years now—there has been very little net temperature change over Antarctica taken as a whole.

What the Steig et al. analysis did do, was to alter the generally accepted spatial pattern of the temperature change across Antarctica. Whereas previous studies showed that the warming was largely limited to the Antarctic peninsula region of West Antarctica with vast areas of cooling occurring distributed across the other parts of the continent, the Steig et al. analysis effectively spread the warming across the entire continent, both during the complete period of record since 1957, as well as during the most recent two-to-three decades (Figure 2).


Figure 2. Spatial patterns of temperature change across Antarctica as determined by Steig et al. for different time periods (adapted from O’Donnell et al., 2011).

Almost immediately, speculation popped up across the blogosphere that something was seriously amiss with Steig’s methodology. Analysts zeroed in on the problems and went on to publish in the scientific literature their own version of the spatial patterns of temperature change across Antarctica using the same data as Steig et al. used (a combination of surface observations and satellite-borne measurements) but employing a new and improved technology.

Surprise, surprise. The “new” map of temperature change across Antarctica produced by O’Donnell et al. wasn’t all that much different from the pre-Steig vision of the temperature changes which had taken place. Once again, the warming was primarily constrained to the Antarctica Peninsula, and cooling could be found across large regions of the rest of Antarctica (Figure 3).


Figure 3. Spatial patterns of temperature change across Antarctica as determined by a methodology used by O’Donnell et al. for different time periods (adapted from O’Donnell et al., 2011).

The situation presented in Figure 3 is much different from that presented in Figure 2.

For those who still question whether or not the O’Donnell et al. methodology is superior to the Steig et al. methodology, there is an independent arbiter—the satellite-derived temperature of the lower atmosphere that has been compiled and maintained by Roy Spencer and John Christy, and which just celebrated its 33rd birthday on December 1, 2011. The Spencer and Christy temperature record employs a different sort of satellite-borne temperature instrument (a microwave sounder unit, or MSU) than the satellite data melded with the surface observations in the Steig et al. and O’Donnell et al. studies, and is as a completely independent temperature data source.

Figure 4 shows the south polar projection of the trends in the lower atmosphere as derived from Spencer and Christy’s MSU data from December 1978 through November 2011. Compare Figure 4 with the lower two panels of Figures 2 and 3.


Figure 4. Spatial patterns of temperature change across Antarctica as determined by the MSU satellite data, December 1979-November 2011 (figure provided by John Christy).

Notice that there is a lot of blue shading on this map indicating regions where the temperature trend is negative (cooling), and that the regions of warming are primarily located along the continental margins.

The Spencer and Christy trends from the lower atmosphere are a decent (although imperfect) match with the O’Donnell et al. temperature trends of the surface. The Steig et al. trend analysis as the odd-one-out.

In the two years since the big flash at Nature, further and better analysis confirms that what has been going on in Antarctica is pretty much what we knew to be happening all along—that during the last 3-to-4 decade period of rapid build-up of atmospheric carbon dioxide, the temperature has changed little at the continental scale, and instead is characterized by a complex pattern of regional warming and cooling. Such changes do not foreshadow a rapid loss of continental Antarctic ice nor an alarming Antarctic contribution to the rate of current and future sea level rise this century as a result of surface ice melt. In fact, measurements from a different satellite data set that begin in 1979 show that the extent of ice in the southern high latitudes is increasingly significantly.

References:

O’Donnell, R., et al., 2011. Improved methods for PCA-based reconstructions: case study using the Steig et al. (2009) Antarctic temperature reconstruction. Journal of Climate, 24, 2099-2115.

Steig, E. J., et al., 2009. Warming of the Antarctic ice-sheet surface since the 1957 International Geophysical Year. Nature, 457, 459–462.

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32 thoughts on “Steig et al, revisited with UAH satellite data

  1. Its hard to believe that NATURE ever published this drivel by Steig et al., They are an affront to science. I hope that eventually there will be full retraction of this paper.

  2. Fitzcarraldo says:
    January 3, 2012 at 2:22 pm

    As they say, Nature ain’t what it used to be. Same for Scientific American, now both owned by the same German corporation, with an agenda.

  3. It is sad to see my old friend the Scientific American go senile. Once upon a time it was about science. Ah well, into the never renew box it goes.

  4. Stephan Barski says: “Of course they never mention that a change from -50 to -40 still leaves a lot of degrees to go before we reach 32.”

    Actually, Steig himself said something very similar to that early on, something to the effect that the Antarctic cap wasn’t going to melt anytime soon at the picayune heating rates achieved in his paper.

    The importance of his paper was that GW theory says warming will affect the polar caps first. He purported to show some warming where the Warmists wanted it. Mission accomplished.

  5. The spatio-temporal inconsistency of 30-yr “trends” over mountainous continents is apparent from relatively sparse vetted station records. It’s nice to see that data characteristic (if only for one temporal snapshot).with spatial resolution that only satellites can provide,

  6. Funny…. change the start date to obtain the result you want….

    long term net is almost zero….

    GOT to love propaganda….

  7. Fantastic work by O’Donnell, R., et al., but sadly, the Steig misinformation will remain as entrenched dogma by the Warmistas just the as the incredibility well debunked hockey stick has.

  8. Bill H says:
    January 3, 2012 at 6:13 pm
    Funny…. change the start date to obtain the result you want….
    long term net is almost zero….
    GOT to love propaganda….
    ================================================
    It’s easier than that.
    Just change the base period !!!

  9. @Al Gored: What do you know about the owners of Nature & Sci. Am? I thought they were British & American respectively. Any evidence of the parent company inserting “right-thinking” editors?

  10. What Stieg did was exactly what Mann tried to do the MWP. He tried to massage data that didn’t fit the narrative of AGW. Mann tried to erase medieval warming to show that current global warming is unprecedented. Stieg tried to show that there actually was warming in Anarctica in order to show that current global warming is unprecedented.

  11. JDN says:
    January 3, 2012 at 7:27 pm
    @Al Gored: What do you know about the owners of Nature & Sci. Am? I thought they were British & American respectively. Any evidence of the parent company inserting “right-thinking” editors?

    Answer to first part here: (German multi-national)

    http://en.wikipedia.org/wiki/Nature_Publishing_Group

    Second part: Good chance if you change it to “left-thinking” editors.

  12. Why is looking at patterns rather than averages so prevalent in so many scientific fields these days? The patterns show clear hot spots which feed into progressively dispersed temperature increases at lower levels. This to any engineer would spell an area overheating but the heat being carried away and would immediately result in not an investigation as to why the average was higher but what caused the local heating.
    When someone in the climate studies field discovers a hitherto unknown massive natural hot gas gun at the source I am amazed that instead of wondering if this might be the cause and investigating this further, it is used as justification for more panic. They appear to still be emphasising how the resulting gas is going to go into the atmosphere as a result of man made warming melting the north pole ice instead of whether the far more probably idea that this is melting the Arctic pole directly as hot gas.
    Can climate studies still be seriously considered as a profession or has it had a whole generation of mindless conformists to AGW recruited, incapable of any non standard thought?

  13. Better hold on to your January 22, 2009 issue of Nature if you have one. Like the1918 flawed U.S. postage stamp with its *upside down* biplane image, or the 2007 flawed George Washington silver dollar with its *missing* data, the Nature issue could become a valuable collectable.

  14. Some seem think warmer=melting, regardless of the absolute temperature. Most of what melting occurs in Antarctic is due to surface heating which is much more than the air temperature, but still trivial. Other loss is due to subsurface heat from the Earth at bottom of the ice sheet (not exactly due to human causation…).

  15. Not being a scientist of any sort and looking at this logically, do not the wind and ocean current patterns around Antarctica travel in a clockwise direction? If that’s the case, it seems only natural that the archipelago would always have a slightly warmer climate than the more eastern and central regions of the continent as the archipelago and South America act as a choke point. . If the water were even slightly (however little so over the last century) warmer, would that not increase the humidity of the air flowing to the east thereby making it proportionately colder (again, however small that decrease in temperature might be)?
    Or, is there something wrong with my logic gland? ;-)

  16. I guess it would be interesting for some technical expert to review honestly just how good, accurate, reliable and reproducible the satellite measurements are, since this discussion appears to produce rather different conclusions in different publications, doesn’t it?

    Or is some kind of ‘temperature fudging’ going on, turning the raw data into something else?

    Do let us know…..

  17. The maps in Steig, et al. are a joke. Only three long term temperature records exist for the continental interior. All of the other monitoring stations have been or are located near the coasts. Three monitoring stations for an area larger than the continental US! And from those three stations look at the Stieg, et al. maps showing imagined detail. Even the UAH satelite data which records twice a day everything north of 80-degrees, the kind of spacial detail is large areas vs. the imagined Steig, et al. detail.
    What a joke.

  18. As one of the authors of O’Donnell et al 2011, I am naturally pleased to read this article. However, one note of caution. I’m not sure how reliable the generally excellent UAH LT AMSU satellite data is over most of Antarctica, due to its height. The UAH readme file for the AMSU data says:

    “ALSO BE CAUTIOUS USING LT AND MT OVER HIGH TERRAIN ( >1500 M)
    The areas of poor anomaly values are : Tibetian Plateau, Antarctica, Greenland and the narrow spine of the Andes.”

    That may well account for part of the discrepancies between the the1979-2003 trends shown in our study and the 1979-2011 trends shown in the UAH LT map. The near 8 year difference in end dateis also significant.

    A couple of brief comments.

    Steig et al avoided the above-noted problems with the AMSU data by using the AVHRR data from polar orbiting satellites, which measures the ‘skin’ temperature of the surface rather than the lower troposphere air temperature measured by the AMSU. Unfortunately, the need for masking to remove the effects of clouds makes the data very noisy, and there appear to be substantial drifts over time and one or two jumps upon change of satellite, and the high trends (used by Steig et al over 1982-2006) are almost certainly wrong. We used the same cloudmasked AVHRR data, but only for its spatial correlation information, which is little affected by the drift and jump problems, to derive our results – all our trend data came from the more reliable surface stations.

    Steig et al’s results are invalid even apart from the misuse of the AVHRR satellite data, due to very inappropriate choices made when applying their mathematical methods. In particular, their retention of too few principal components in the reconstruction resulted in the high warming in the peninsular strongly affecting trends shown for most of West Antartica.

  19. When you come down to it Steig problems are the same as Mann’ poor stats and poor methodology, and just like the ‘stick’ pal review wave-through which lead to mistaken not being seen before publication becasue ‘the cause’ blinded the reviewers to what the paper actual contained .

  20. I am concerned that all of the plots, even O’Donnell’s, seem to extrapolate over vast distances that may not be appropriate. Is the detail shown on the plots valid? If one takes the Ross Ice Shelf (the bite out of the bottom of the map), which is about the size of France, there is Scott / McMurdo base on the northwestern edge with a known UHI, Siple way out to the East and South Pole. That is it for manned weather stations. Out on the shelf, they are constantly swept by the katiabatic winds coming off the polar plateau through the gaps in the Transantarctic Mountains. That means the weather out there would be more influenced by the pole, rather than the ice shelf edge conditions. There have been remote unmanned stations at various parts of the shelf over the years but there have been a lot more problems with these than the data indicates. Instrument drift is a real issue.
    Though it is only weather, when I was there, we often had totally different conditions up near Mt Melbourne than Scott Base just 400km away. We were very affected by the winds coming down the glaciers. The map also shows big differences between Scott and Vanda, which are neighbours as far as Antarctica is concerned. If you go back to the journals of a century ago, Scott’s sledging party had significantly different conditions to that of his base at Cape Evans.
    I don’t know whether they did it or not as I couldn’t pick it up in O’Donnell’s paper, but was comparison plotting tried by leaving out bases to see if the detail significantly changed? That would soon establish the robustness of the interpretation

  21. I’d like to note that rather than make derogatory comments against Prof. Steig and impune his name and motives, people consider the comment of Nic Lewis, who criticizes methodology and not character.

    It is possible that some of the decisions made by Prof Steig’s group during the coarse of their analysis reflect certain biases and internal filters. I’d argue this is something all of us experience on a daily basis and is more likely the norm than the exception. What matters is that the methodolgy and data was out there to be analyzed. Assuming the scientific process works the way it should, we will eventually end up knowing a tiny bit more.

  22. timg56 says:
    January 4, 2012 at 4:24 pm
    It is possible that some of the decisions made by Prof Steig’s group during the coarse of their analysis reflect certain biases and internal filters.

    Freudian slip?

    I’d argue this is something all of us experience on a daily basis and is more likely the norm than the exception. What matters is that the methodolgy and data was out there to be analyzed. Assuming the scientific process works the way it should, we will eventually end up knowing a tiny bit more.

    I don’t recall seeing O’Donnel et al on the cover of Nature, so no, the process didn’t work.

  23. “Almost exactly two years ago,”

    I’ve had a long week at work, but I’m pretty sure that January 2009 was THREE years ago, seeing as we are now in 2012….

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