Palmyra Atoll Coral Proxy in Gergis et al 2012

There is a lot of discussion on Bishop Hill (here and here) and Climate Audit of a new paper in Journal of Climate “Evidence of unusual late 20th century warming from an Australasian temperature reconstruction spanning the last millennium“, with lead author, Dr Joëlle Gergis. The reconstruction was based upon 27 climate proxies, one of which was a coral proxy from Palmyra Atoll.

There are two issues with this study.


The study is a “temperature reconstruction for the combined land and oceanic region of Australasia (0°S-50°S, 110°E-180°E)“. The study lists Palmyra Atoll as being at 6° S, 162° E, so within the study area. Wikipedia has the location at 5°52′ N, 162°06′ W, or over 2100Km (1300 miles) outside the study area. On a similar basis, Rarotunga in the Cook Islands (for which there are two separate coral proxy studies), is listed as being at 21° S, 160° E. Again well within the study area. Wikipedia has the location at 21° 14′ 0″ S, 159° 47′ 0″ W, or about 2000Km (1250 miles) outside the study area. The error has occurred due to a table with columns headed “Lon (°E)”, and “Lat (°S). Along with the two ice core studies from Vostok Station, Antarctica (Over 3100km, 1900 miles south of 50° S) there are 5 of the 27 proxies that are significantly outside the region.

Temperature Reconstruction

Palmyra Atoll reconstruction is one of just three reconstructions that has any data before 1430. From the abstract, a conclusion was

The average reconstructed temperature anomaly in Australasia during A.D. 1238-1267, the warmest 30-year pre-instrumental period, is 0.09°C (±0.19°C) below 1961-1990 levels.

From the proxy matrix I have plotted the data.

This indicates a massive change in late twentieth century temperatures, with 1996 being the most extreme on record.

The other two data sets with pre-1430 data are tree ring proxies from Mount Read, Tasmania and Oroko, New Zealand. These I have plotted with a 30 year moving average, with the data point at the last year.

There is something not right with the Palmyra Atoll proxy. The late 20th century trend is far too extreme. In the next posting I will compare to some other coral data sets.


  1. Brian H

     /  07/06/2012

    The 20th Century was the warmest in the last 100 years! Calambabombity is upon us! Or is about to terminally eventuate us!

    Recycle your breadcrumbs! Save the wheat!


  2. pouncer

     /  10/06/2012

    Is there a cite for the Long/Lat besides Wikipeidia, which many consider unreliable?

    • manicbeancounter

       /  10/06/2012

      I only looked up the Wikipedia stats, bit I do not think they are unreliable. A quick look at Palmyra Atoll or Rarotonga on Google Earth or Bing will confirm the general accuracy.

      Wikipedia tends to be unreliable where opinion on global warming is concerned (see for instance hockey sticks). I do not think it would get wrong matters of geography where (a) there is no benefit (b) a quick check elsewhere would confirm their errors.

  3. And not a single proxy from mainland Australia. Am I right?


    • manicbeancounter

       /  10/06/2012

      Exactly right.

      A map is on page 46 of a backup copy, showing the locations. The dots do not add up to 27, as there are at least 3 places with two proxies.

      Click to access melbourne.pdf

  4. ferd berple

     /  14/06/2012

    I’ve been to Palmyra. Sailed there on a yacht. It is 1000 miles due south of Hawaii. It is at 5N, 162W. They have the N and W reversed. There is nothing except ocean at 5S, 162E,+162%C2%B0+e&cp=13&gs_id=7&xhr=t&q=6%C2%B0+S,+162%C2%B0+E

    • manicbeancounter

       /  14/06/2012

      I’ve been to Palmyra. Sailed there on a yacht” – I’m jealous. Having looked up the locations, these coral islands look wonderful – at least for a visit.

      I had already noticed the errors in the locations due to a table with columns headed “Lon (°E)”, and “Lat (°S)”. For me this indicates both sloppiness, and like the substantial variations in C20th warming trends, and a failure to sense-check the results.

  5. ferd berple

     /  14/06/2012

    We certainly enjoyed the 3 months we were there. I was sailing with my wife and infant daughter which made it a special time in my life. Had supplies not been running low and the seasonal weather (cyclone) window closing to the South Pacific, we would have stayed longer.

    As you correctly have noted, Raratonga in the Cooks is further east of Palmyra. We were headed to the Cooks from Palmyra, but were not able to make sufficient easting against the SE trades after crossing the ICZ and fell off for Samoa.

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