the Air Vent

Because the world needs another opinion

History

Posted by Jeff Id on December 8, 2011

The following paragraph is from the zero order draft of the IPCC on the controversial topic of polar amplification.   The topic is only controversial because one of the two poles is doing a poor job of cooperating with climate models.  Of course some of the pro’s will tell you different, but my understanding is that there is less warming in the Antarctic than was predicted in most models.  Like hide the decline in paleoclimatology, there are random theories for the anti-establishment behavior of the Antarctic thermometers (i.e. ozone), however my understanding is that the guesses are unsubstantiated outside of some models which have the ‘guess’ programmed right into them.  Please understand that I haven’t spent much time with the models (more than most) but as always, you should confirm my opinions yourself.

Kenneth noticed this next paragraph (from the AR5 ZOD on another thread which I’m not quoting or citing it but it happens to randomly appear below) that discusses ‘polar amplification’ – a phenomenon describing more warming over the poles than the rest of the planet.

Box 5.1: Polar Amplification
Instrumental temperature records show that the Arctic (Bekryaev et al., 2010) and the Antarctic Peninsula [(Turner et al., 2005; Turner et al., 2009)] are experiencing the strongest warming trends (0.5°C per decade over the past 50 years), almost twice larger than for the hemispheric or global mean temperature [(IPCC, 2007)]. West Antarctic temperature also displays a warming trend of about 0.1°C per decade over the same time period (Steig et al., 2009; [Reference needed: O'Donnell et al., ?]). A number of mechanisms can produce larger magnitudes of polar temperature changes compared to mid or low latitudes. These mechanisms involve the dynamics and variability of atmosphere (Alexeev et al., 2005; Serreze and Francis, 2006) and the ocean-sea ice system (Chylek et al., 2009; Polyakov et al., 2010; Semenov et al., 2010; Spielhagen et al., 2011b), as well as local radiative feedbacks linked with snow (Ghatak et al., 2010), ice albedo, water vapour, clouds (Graversen and Wang, 2009; Screen and Simmonds, 2010), and land surface vegetation changes (Bhatt et al., 2010). Each of these mechanisms has specific fingerprints in the seasonality, latitudinal and vertical structure of temperature changes. Detection/attribution studies conducted for the Arctic and Antarctic (Gillett et al., 2008) concluded that human influence dominated the recent polar warming.

The first claim of 0.5C/Decade in the peninsula region is easily confirmed as reasonable (slightly high) with this area plot derived from the raw temperature station data below.   The 50 year Antarctic continental trend from the station data is a statistically insignificant 0.05C/decade of warming.

verondi 63 station

Antarctic temps by ground thermometer. AWS and Manned

What is interesting is that the Steig et al., which reports the incorrect 0.2C West Antarctic trend.   “West Antarctic temperature also displays a warming trend of about 0.1°C per decade over the same time period (Steig et al., 2009; [Reference needed: O'Donnell et al., ?]).”  The writers at this point were aware of the maximum warming value from our paper (0.06-0.1)   The o.1 value from O10 which was the more likely result but the 0.06 wasn’t invalid.

From climategate 2.0 email #2095, Eric Steig wrote:

 He’s skeptical that the warming is as great as we show in East Antarctica — he thinks the “right” answer is more like our detrended results in the supplementary text.  I cannot argue he is wrong. Writing a paper together with him to clarify all this would be useful, I think.

Fairly interesting considering that the email date was Jan 22, 2009 and when the famous paper was announced at RC to be on the cover of Nature only one day before.

The quote from the Nature cover description linked in the Real Climate article above was:

A new reconstruction of Antarctic surface temperature trends for 1957–2006, reported this week by Steig et al., suggests that overall the continent is warming by about 0.1 °C per decade. The cover illustrates the geographic extent of warming, with the ‘hotspot’ peninsula and West Antarctica shown red against the white ice-covered ocean. [Cover image: NASA Goddard Space Flight Center/University of Washington/USGS]

We found something a little different..

While we do find overall warming of the continent, the continental average is not significant at the 5% level (≈0.06 +/- 0.07 oC decade-1) 5, nor is the warming in East Antarctica (≈0.03 +/- 0.09).

Unlike S09, we find the Peninsula regional average to demonstrate the most strongly positive trend, at 0.35 +/- 0.11 from 1957 – 2006.

For West Antarctica, the RLS reconstruction demonstrates a statistically significant trend of 0.10 +/- 0.09 (approximately half that reported by S09) while the E-W reconstruction shows a trend of 0.06 +/- 0.07.

One method’s trend just crossed 95% significance, while the other did not. Whereas the O10 near perfect replication of Steig et al. showed:

For the period of 1957-2006, our replication yields linear trends in oC decade-1 of 0.12 for all grid cells, 0.10 for East Antarctica, 0.13 for the Peninsula and 0.20 for West Antarctica.

The smearing effect is seen in reduced peninsular trends and increased continental and more importantly to the Steig’s group, statistically significant West Antarctic trends.

Antarctic regions per O10

Steig et al. on -0.5 to 0.5 scale with same color distribution as O10

O10 optimal result on right side

I’ve made the point many times that Ryan and Nic’s methods minimized the tendency for station information to be blended into neighboring stations.  The red tail from the peninsula in the left image above is a good example.  They optimized the method but it is impossible to fix the issue entirely.   You can see in the right pane immediately above that the peninsular warming has a band of yellow running horizontally between two blue regions that I consider to be a real effect but the magnitude of the trends shown are partially an artifact of the principal component methodology.   With that said, the simple methods of the first figure prove that actual patterns are very close to the real trends and despite the politically correct IPCC narrative where everyone gets a blue ribbon, they do contradict Steig et al.

Will O10 make the final cut?

As a minor author would that mean that I still need to turn in my skeptic card?

8 Responses to “History”

  1. What’s the 30 year trend?

  2. steveta_uk said

    “As a minor author would that mean that I still need to turn in my skeptic card?”

    Will you get to share in a Nobel?

  3. Jeff Id said

    Will,

    Our paper is at this link with all of the various reviews and steps.

    http://www.climateaudit.info/data/odonnell/

    The SI contains a variety of trend information. There are 4 papers and SI’s.

  4. Steve Fitzpatrick said

    Does O’Donnell et almake the cut or no? Maybe you could start a betting pool. My guess: somehow they keep it out, even “if they have to redefine the peer reviewed litchurchur”.

  5. Kenneth Fritsch said

    What is of interest to me here is that they quote a number closer to O’Donnell’s than Steig’s and then seem to not know where to reference O’Donnell. I would bet that the how close O’Donnell comes to not seeing the trend as different than zero (with one method they do not reject the null hypothesis that it is zero and the other barely) will be quietly ignored.

    My analysis of the S(09) and O(10) says that besides the methodology problems connected with S(09) the use of the AVHRR data in S(09) to obtain temporal trends and not merely to obtain spatial correlations with ground stations as was the case in O(10) is what created the problem with West Antarctica. It is also of interest (and again something I would bet that is not detailed in the IPCC) that when coming forward with trends from the 1956 start date used in S(09) the trends different than zero disappear quickly for West and East Antarctica – but, of course, not for the Peninsula. Also of interest is that large parts of the Antarctica saw the warmest years before the 1956 start date based on ice core analysis that Steig was a major part of.

  6. You don’t need models to demonstrate “polar amplification”. Just look at physical measurements. Ice cores provide temperature proxies for high latitudes, namely GISP, GRIP & DYE in Greenland or Vostok and various domes in Antarctica. For low latitudes there are plenty of good proxies from sediments etc.

    Forget the bristlecones; even if they were believable they don’t go back far enough.

    I have only analysed GISP data which show that “temperature increase over the period is 2.3 Centigrade compared to the IPCC’s ~0.8 Centigrade for the same period (see AR4). These numbers seem to fit the idea that temperature changes are magnified at high latitudes……”.

    See:

    http://diggingintheclay.wordpress.com/2010/12/30/dorothy-behind-the-curtain-part-2/

  7. vukcevic said

    OT but might be of interest:
    Recent article by statistician Grant Foster Tamino
    Global temperature evolution 1979–2010

    http://iopscience.iop.org/1748-9326/6/4/044022/pdf/1748-9326_6_4_044022.pdf

    it’s absolute nonsense!

  8. Nic L said

    Jeff

    Interesting non-quotation from the ZOD.

    The uncertainty band for Steig’s West Antartica trend was almost certainly very substantially understated in his Nature paper, as it only took into account the residual variance from the trend fit and serial correlation. I had an exchange of emails with Ryan about this, which you were copied into (search for one whose title included the phrase ‘ error sources in trend regressions’, if you are interested, or I can send you a copy). I suspect that with full allowance for errors the W. Antarctica trend would not have been significant

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