NZ cranks finally publish an NZ temperature series – but their paper’s stuffed with errors

By Gareth Renowden 31/10/2014


You can’t teach old dogs new tricks, it seems — certainly not if they’re gnawing a much loved old bone at the time. The lads from the NZ Climate Science Coalition — yes, the same boys who tried to sue NIWA over the New Zealand temperature record and lost, and who then folded a trust to avoid paying court-ordered costs — have finally found a learned journal gullible enough to accept and publish their shonky reworking of NZ’s temperature record. Earlier this month Environmental Modelling and Assessment published A Reanalysis of Long-Term Surface Air Temperature Trends in New Zealand by CR de Freitas & MO Dedekind & BE Brill (DOI 10.1007/s10666-014-9429-z).

My attention was drawn to dFDB 2014 by an NZCSC press release, and yesterday Richard Treadgold, the man who kicked off the whole sad affair five years ago, posted a disingenuous and misleading article about the paper at his blog. As you might expect given the authors, the paper does not call for an upward revision in the amount of warming NZ has experienced over the last century. The abstract concludes with the following:

Current New Zealand century-long climatology based on 1981 methods produces a trend of 0.91 °C per century. Our analysis, which uses updated measurement techniques and corrects for shelter-contaminated data, produces a trend of 0.28 °C per century.

As you might also expect, given the authors and their respective track records, the paper is riddled with schoolboy howlers and outright misrepresentations. It would probably never have seen the light of day without the assistance of Chris “Pal Reviewde Freitas and his undoubted ability to steer tosh to publication.

Here’s a partial list of the errors, misdirections, misrepresentations and shoddy scholarship in the paper, and in the approach taken by de Freitas, Dedekind and Brill (dFDB 2014).

dFDB 2014 repeats the old canard that NIWA’s Seven Station Series (7SS) before the 2010 review was based on the adjustments made in Jim Salinger’s 1981 thesis. This was a key claim in the NZ Climate Science Education Trust‘s evidence to the High Court and so transparently at odds with written reports and papers from 1992 onwards that it was easy for NIWA to refute. As one close observer of the case told me:

Judges may not understand maths, but they are pretty good at English, and take a dim view of litigants who wilfully and perversely misrepresent simple English sentences.

dFDB 2014 derives a warming rate of +0.28ºC per century, by claiming to apply a method published by Rhoades and Salinger in 1993 (RS93). It claims to create a new benchmark record by reapplying an old technique — essentially ignoring all the work done by NIWA in deriving the current 7SS. Unfortunately, the paper is based on a misapplication of the very method it claims to rely on, and includes numerous errors.

The paper as published contains no workings or supplemental material that would allow reproduction of their results, but it appears to be essentially identical to an “audit’ of NIWA’s Seven Station Series conducted by the NZCSC, and which was offered as evidence in their trust’s attempt to sue NIWA.

As such it contains mistakes that were pointed out in NIWA’s evidence to the High Court — evidence which was extensive, thorough and damning, but is not (yet) available in the public domain.

dFDB 2014 claims that RS93 mandates the use of one year and two year periods of comparison data when making adjustments for a station change, but RS93 makes no such claim. RS93 uses four year periods for comparison, in order to ensure statistical significance for changes — and no professional working in the field would use a shorter period.

The choice to limit themselves to one and two year comparisons seems to have been deliberately made in order to limit the number of adjustments made in the reconstructed series. Limiting the comparison periods makes it harder for adjustments to reach statistical significance, leading dFDB 2014 to reject adjustments even in cases where the station records show site moves or changes!

The effect of that is to reduce the warming trend because, as Treadgold’s first venture into this field showed, a naive reconstruction of the raw data shows not much warming.

But perhaps the most critical flaw in dFDB 2014 — one that should have been sufficient to prevent publication in any self-respecting journal operating a credible peer review process — is that their method ignores any assessment of maximum and minimum temperatures in the adjustment process. This was pointed out to the authors in NIWA’s evidence in the High Court. One of these adjustments will almost always be larger than that for the mean, and if that change is significant, then the temperature record will need to be adjusted at that point – it doesn’t matter if the mean temperature adjustment is statistically significant or not.

Silly mistakes in the application of their version of RS93 appeared in the “audit”, were pointed out in NIWA’s evidence to the High Court, but appear to be uncorrected in dFDB 2014. For example, in the “audit”, they infill a month of missing data (May 1920 in the Masterton series) by choosing an unrealistically warm temperature based on an average of years around the adjustment date. This ignores the fact that May 1920 was one of the coldest Mays on record, at all sites involved in the adjustment calculation.

The dFDB 2014 infill has the effect of reducing the statistical significance enough to reject an adjustment — despite the station record clearly showing that an adjustment is required! Any other approach — skipping the month, making a reasonable estimate based on surrounding stations, or even leaving the unrealistically warm guess at the start of the new series but looking at three years instead of limiting it (wrongly) to two years would make an adjustment necessary.

Throughout dFDB 2014, the analytical choices made by the NZCSC team have the effect of reducing the warming trend, and thus minimising the appearance of the very real warming NZ has experienced over the last century. Very convenient choices given their ideological stance on climate change, a cynic might note.

Quite apart from the methodological issues — which are undoubtedly huge — dFDB 2014 makes no reference to the Eleven Station Series (11SS) derived by NIWA from temperature sites that need no adjustments, presumably because it tracks warming at the expected level1 — that is, three times faster than dFDB 2014 finds.

One might speculate that if they had chosen to “audit” the 11SS — which has a strong warming trend in the raw station data2 — they would have been desperate to find adjustments to reduce that trend.

dFDB 2014 fails to acknowledge the existence of or address the issues raised by NIWA scientist Brett Mullan’s 2012 paper in Weather & Climate (the journal of the Meteorological Society of NZ), Applying the Rhoades and Salinger Method to New Zealand’s “Seven Stations” Temperature series (Weather & Climate, 32(1), 24-38), despite it dealing in detail with the method they claim to apply. Perhaps this is because it points out most of the egregious mistakes they made in their “audit”.

dFDB 2014 also fails to make any reference to sea surface temperature records around the country and station records from offshore islands which also support warming at the expected level — as does the well-documented reduction in ice volume in the Southern Alps.

Beyond any doubt, dFDB 2014 is a model of shoddy scholarship. How on earth did it get accepted for publication by Environmental Modelling and Assessment? An earlier version of dFDB 2014 was submitted to a much more relevant journal, Theoretical and Applied Climatology, but was sent back to the authors for substantial revision at least twice before being rejected. One can surmise that in that case peer review was an uncomfortable process for de Freitas, Dedekind and Brill because the peers being consulted were professional climatologists who understand the nitty-gritty of station adjustments.

At EMA, de Freitas seems to have found a more compliant editor and friendlier reviewers — so friendly that they were happy to allow an obviously and critically flawed paper through to publication. A few simple checks by the editors and reviewers should have raised warning flags.

They should have noted that de Freitas presents himself as lead and corresponding author, yet has no publishing track record in climate records and their homogenisation. He acts as front man for Dedekind and Brill — two men with no relevant academic affiliations or any publication track record — effectively prostituting his position at Auckland University to usher yet another rubbish paper through to publication3. If that wasn’t enough, then competent reviewers should have noted the obvious critical flaws and demanded changes.

As an example of ideologically-driven data torture, A Reanalysis of Long-Term Surface Air Temperature Trends in New Zealand is hardly unusual in the world of climate denial. What makes it stand apart is that such a poorly put together and politically-inspired effort has made its way into the peer-reviewed literature. That is a sign of a gross editorial failure by Environmental Modelling and Assessment, and it should be immediately withdrawn. Meanwhile, the NZ temperature record will continue to show what it always has – substantial and highly significant warming over the last 100 years.

  1. The level demonstrated by NIWA’s re-working of the benchmark Seven Station Series, 0.91ºC per century since 1909
  2. A powerful argument why there should also be one in any homogenised 7SS.
  3. See “Pal Review“, and the Maclean, De Freitas & Carter saga for other examples of de Freitas playing fast and loose with the accepted conventions of scientific peer review.