The UnAustralian

Wednesday, September 03, 2003
So What Is Wrong With Soon and Baliunas Research Paper

I've already blogged about the string of resignations in the journal Climate Research, so this post isn't about the rapid decay of a scientific journal, but rather is a look at the problems with the research paper that started the whole affair.

The paper by Soon and Baliunas is titled Proxy climatic and environmental changes of the past 1000 years, and is virtually identical to a paper published earlier by the same authors (+ a collection of names from the skeptics cesspit). The paper tries to determine if there was a global medieval warm period, a global little ice age, and whether or not the temperatures during the MWP were hotter than the 20th century temperatures. It tries to investigate this, not by doing experimental research, but by reviewing preexisting research papers.

There is absolutely nothing wrong with doing this. Rather, the failed reform attempt and consequent resignations, came about because the paper utilises a very flawed methodology, which is virtually certain to give the types of answers which the researchers desire, rather than an objective view of the literature. There are three main problems, identified by a paper in Eos, with the methodology.

* The authors don't differentiate between hot, cold, wet and dry. For example, if a proxy shows that it was wetter during the MWP relative to the 20th century, then the authors treat the study as saying it was warmer during the MWP.

* Because the authors summarise a large number of local studies, they are dominated by local events. The temperature at a certain location and at a certain time depends on both the global mean (what the 20th century tempertures data-set measure) plus local effects. Because, the authors don't try and average out all of the research (instead, they simple state whether or not there is a peak sometime during the MWP, and likewise with the LIA), they are essentially comparing global + local tempertures with modern global tempertures. Given that there are considerable local differences, this artificially inflates the MWP and LIA anomalies. In order to remove local effects, one should average a large number of readings from widely separated proxies, the authors didn't do this.

* Many of the studies compare the MWP to mean 20th century tempertures. However, because have been increasing right throughout most of the 20th century, this gives a misleading result. Or put another way, the tempertures at the end of the 20th century are significantly higher than the average temperature of the 20th century.


M. Mann, C. Amman, R. Bradley, K. Briffa, P. Jones, T. Osborn, T. Crowley, M. Hughes, M. Oppenheimer, J. Overpeck, S. Rutherford, K. Trenberth and T. Wigley. On Past Temperatures and Anomalous Late-20th Century Warmth Eos, 84, 256, 2003

W. Soon and S. Baliunas. Proxy climatic and environmental changes of the past 1000 years Climate Research, 23, 89, 2003.

W. Soon, S. Baliunas, C. Idso, S. Idso and D. Legates. Reconstructing climatic and environmental changes of the past 1000 years: a reappraisal Energy & Environment, 14, 233, 2003
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