A topsy turvy world of climate proxies

I would like to think that I would recognise a graph of the data from one of my paper. Perhaps that is optimistic; I’ve not looked at some of my papers for years. Still, the graphs of oxygen isotopes of two species of forams from Murray Canyon reproduced in a new paper by Soon et al looked weird.

More negative values of δ18O in foram tests are associated with warmer water temperatures, so by convention the data are inverted when plotted so negative values, warmer waters, are uppermost. Soon et al had plotted it so positive values, cooler temperatures, are uppermost.

Soon et al are using wavelet analyses to test for “solar-linked climatic variation on centennial and millennial timescales”, with a new multiple cross-wavelet transform. A the usual cross-wavelet transform looks for common power and phase relationships between two proxy records, Soon et al have extended this to consider multiple proxies simultaneously.

Since Soon et al are interested in phase relationships, the orientation of the data matter – a proxy and its inverted self are anti-phased. If Soon et al had arranged all proxies so that cool was up, everything would be fine. But the sea surface temperature record from Stott et al (2004) are plotted warm up.

It is not possible to eyeball the data in Soon et al to see if the reported phase relationships are credible, with or without inverted proxies, as the proxy records are all plotted on their own age scale, preventing comparison.

The time series for the 3 solar activity proxies [(1) Nitrate, (2) 10Be, and (3) 14C] and 7 climatic proxies [(4) Relative Gray Index-RGI, (5) Total Organic Carbon-TOC, (6) Sortable Silt mean size, (7) Hematite stained grains-HSG, (8) Sea surface temperature-SST, (9) G. bulloides δ18O, and (10) G. ruber δ18O] over the Holocene used in this study.

The time series for the 3 solar activity proxies [(1) Nitrate, (2) 10Be, and (3) 14C] and 7 climatic proxies [(4) Relative Gray Index-RGI, (5) Total Organic Carbon-TOC, (6) Sortable Silt mean size, (7) Hematite stained grains-HSG, (8) Sea surface temperature-SST, (9) G. bulloides δ18O, and (10) G. ruber δ18O] over the Holocene used in Soon et al.

Of course it is possible that this is just a plotting error, and that the analyses have been done correctly, but there is nothing in the text to suggest this. Soon has a history of awful papers; I’m not inclined to trust this one – there is plenty more that could be questioned.


Soon et al. 2014: A review of Holocene solar-linked climatic variation on centennial to millennial timescales: Physical processes, interpretative frameworks and a new multiple cross-wavelet transform algorithm. Earth-Science Reviews, 134, 1–15

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About richard telford

Ecologist with interests in quantitative methods and palaeoenvironments
This entry was posted in Fake climate sceptics, Peer reviewed literature, solar variability and tagged , , . Bookmark the permalink.

One Response to A topsy turvy world of climate proxies

  1. Soon et al don’t give much description of their multiple cross-wavelet analysis, instead promising the details in another paper (so the current paper is putting the cart before the horse). In the appendix to this paper they attempt to show that their methods work by analysing three pseudo-proxies consisting of noiseless sine waves. They find that only when all three noiseless waves contain the same frequency does the method report a significance at that frequency.

    As most proxy records are rather noisy, and have some power at all frequencies rather than only at a single frequency, this test gives no indication as to how well their method will work in practice.

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