Wherein we rebut Points 7, 8 & 9
In What Mullan actually says on 7 November I answered the Hot Topic post Danger Dedekind heartbreak blah blah of 5 November, in which Mr Gareth Renowden, presumably advised by Dr Brett Mullan, principal climate scientist at NIWA, had levelled criticisms at the recently published reanalysis of the NZ temperature record. I set out to identify clear, falsifiable statements that Gareth Renowden (or Brett Mullan) was making. There were nine debating points, which you can find in What Mullan actually says. We promised every one would be rebutted.
Dedekind tries [sic] hand wave away the 11SS as having been “thoroughly debunked elsewhere”, but doesn’t link to any debunking. The fact is that the raw station data from rural sites with long records that require no adjustments show strong warming. In other words, the warming seen in the 7SS is not an artefact of site changes or urban warming. That is an important matter, and should have been addressed in dFDB 2014.
Debating point 7. The 11SS is an important record and has not been debunked.
UPDATE 15 Nov 2014 1845 NZST
- Fixed the typo in the last paragraph. Now shows 0.28°C/century warming.
The 11SS is an embarrassment. It was thoroughly debunked as long ago as June 2010 in New Zealand Climate Crisis Gets Worse. That article comments:
“It is almost impossible to avoid the conclusion that NIWA’s political urge to prove a warming trend overcame its professional urge to apply objective scientific principles in constructing a sound and defensible temperature series.”
This is supposed to be a collection of sites that required no adjustments between 1931 and 2008, because there were no significant site or environmental changes.
In fact, every one of the eleven stations underwent changes, some of them huge. Six of the sites didn’t even exist before WW2. Tauranga moved across the harbour to Mount Maunganui. Molesworth’s 1994 change was terminal—it went out of existence. Queenstown’s environmental problems were so bad that Salinger wouldn’t attempt homogenisation in 1992.
The 11SS is a very useful corroboration of the 7SS if confined to the 45-year period that the eleven stations all existed. From 1949 to 1994, the eleven stations did indeed require no adjustments and, revealingly, showed a temperature rise at the rate of
Brett Mullan’s 2012 paper Applying the Rhoades and Salinger Method to New Zealand’s “Seven Stations” Temperature series (Weather & Climate, 32(1), 24-38) deals with the correct application of the methodology described in Rhoades and Salinger’s 1993 paper.
At the very least, dFDB 2014 should have addressed the existence of Mullan’s paper, and explained why the application of RS93 in that paper is not preferable to their interpretation of it.
Debating point 8. The de Freitas et al. (2014) paper should have discussed the relevant literature, including Mullan (2012).
Mullan (2012) is not relevant literature.
In our paper we are at pains to make clear that our aim is to follow RS93 exactly when performing our reanalysis, and that is what we did. Mullan (2012) suggests possible modifications to RS93 (using very long time periods) based on certain samples from the 7SS. It does not address an interpretation of RS93, but sets out the author’s personal perspective on what RS93 should have proposed.
Criticising or modifying RS93 in any way was not within our purview, so Mullan (2012) has no relevance to the journal paper.
Dedekind makes much of the fact that the paper does refer to one paper on SSTs around New Zealand — but skips over the essential point: that the SST evidence confirms that warming is occurring faster than they calculate.
Debating point 9. SST around New Zealand is warming faster than the 0.28°C/century shown in the de Freitas et al. (2014) paper.
SST reconstructions are even more fraught with raw data problems than land-based records, especially in the Southern hemisphere. This is well known (Trenberth et al., 1992). There have been numerous attempts to improve this situation, but none have been successful to the point that anyone could state that a reanalysis of NZ land-based temperature records could be right or wrong based on SST reconstructions such as ERSST.
In our paper we draw attention to Folland & Salinger (1995), mentioning the difference, but we would never make the mistake of assuming SST trends are gold-standard records – especially in this part of the world. Indeed, the Hadley Centre (including Dr Folland) has now officially recognised that its previous assumptions regarding pre-WW2 adjustments to ship records have been mistakenly based.
We would also add that NIWA’s 0.9°C/century was as far above F&S (95) as ours was below it, yet NIWA at no stage withdrew their work due to incompatibility with an SST reconstruction.