By Gareth Renowden 03/05/2018 9


Way back in the spring of 2014, NZ’s little band of climate cranks somehow managed to get a paper published based on their recalculation of New Zealand’s long term temperature record1. The effort – based on calculations done to support their infamous court case against the National Institute of Water and Atmospheric Research (NIWA), which they emphatically lost – purported to show that New Zealand’s long term warming rate was only a third of the amount previously calculated. As I pointed out at the time, it was riddled with errors and bad scholarship, but it appeared in the peer-reviewed literature2, and so required a peer-reviewed rebuttal.

It’s taken a while, but in the last few days Comment on “A Reanalysis of Long-Term Surface Air Temperature Trends in New Zealand” has been published in Environmental Modelling and Assessment3. Led by NIWA principal climate scientist Brett Mullan, the authors are Jim Salinger, who first established the NZ long term temperature record4, Professor Jim Renwick from VUW, and David Wratt, now Emeritus Scientist (Climate), at NIWA, and an Adjunct Professor in the New Zealand Climate Change Research Institute at VUW. You could fairly describe them as experts – and their “comment” might better be called a demolition.

Here’s their conclusion:

In this paper, we identify what we consider to be several methodological flaws in the [de Freitas et al] paper. We conclude that, as a consequence, the temperature trend of an increase of 0.28 °C per century for the period 1909–2009 for New Zealand land surface temperatures derived in the dFDB paper is substantially too low, and that no need has been established for significant downward revision of the trend of around 0.9 °C per century found in previous studies.

They then provide a handy summary of the main flaws – which I’ve paraphrased below:

  • dFDB claimed their paper was the first to properly use a methodology developed by Jim Salinger and Rhoades, first published in 1993. It wasn’t – in two senses. It wasn’t the first, and they didn’t use it properly.
  • dFDB claimed NIWA’s long term temp record was based on calculations from Jim Salinger’s PhD thesis. It wasn’t.
  • dFDB’s interpretation of the Rhoades and Salinger technique was mistaken and flawed, using station overlaps that were too short and ignoring changes in maximum and minimum temperatures. The result was that they failed to make many adjustments that were required, and therefore underestimated the actual warming.
  • dFDB made a few arithmetical errors, dealt with missing data incorrectly, and mishandled trends in the Auckland and Wellington series.
  • dFDB ignored other lines of evidence that support warming of 0.7-1.0°C per century, such as temperature series derived by the Berkeley Earth project, the decline in NZ’s glaciers, and analyses of sea surface temperatures around NZ.

The full paper is well worth a read if you followed the arguments at the time of dFDB’s original publication. It’s an elegant and polite deconstruction of a shoddy, politically motivated piece of work that should never have passed peer review first time round. It should make uncomfortable reading for the remaining authors of dFDB (2015) and their promoters, if they were real scientists rather than propagandists. But they’re not.

[Pink Floyd]

  1. 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)
  2. The lead author, Chris de Freitas (who died last year), had a notable track record of helping rubbish through peer review.
  3. Comment on “A Reanalysis of Long-Term Surface Air Temperature Trends in New Zealand”,Mullan, B., Salinger, J., Renwick, J. et al. Environ Model Assess (2018). https://doi.org/10.1007/s10666-018-9606-6
  4. Jim is currently a visiting professor at the Department of Geography and Environmental Studies, University of Haifa, Mt Carmel, Israel.

9 Responses to “The final cut: crank paper on NZ temperature record gets its rebuttal – warming continues unabated”

  • “…and that no need has been established for significant downward revision of the trend of around 0.9 °C per century found in previous studies”

    Let’s assume for the sake of argument that there has indeed been an overall 0.9 °C average increase in temperature worldwide over the previous century. This means absolutely nothing taken out of the proper context of the history of planet Earth, going back many millennia. I might be wrong, but I don’t see any convincing attempts to provide such a context. This means that the temp. increase over the last century could merely be a fluctuation of mundane proportions, if you look back far enough. A fluctuation is also a trend if you don’t look back far enough to see it as just a fluctuation! While the temp. increase may cause some changes to sea level (as the glacial and interglacial periods of the past have seen time and time again), it has nothing to say about whether any of this is human induced climate change. Even if it is human induced, the likely major cause is deforestation of the tropics, but this hardly gets a mention in all the talk about emissions. Reason? Both deforestation (taxes on palm oil revenue, etc.) and emission taxes are good for governmental coffers, and this is the real driving force behind the climate change movement. They’ll be taxing us for breathing out CO2 next!

  • I might be wrong, but I don’t see any convincing attempts to provide such a context.

    You’re wrong. There is a whole field of study called paleoclimate devoted to teasing out the data on past climates.

    Atmospheric CO2 has just hit 410ppm, a 45% increase on pre-industrial levels, and that is certainly down to human activity – both deforestation and fossil fuel burning. Well understood physics explains how this is driving temperatures upwards. Paleoclimate studies suggest that both the speed of temperature increase, and the amount is unprecedented in (probably) millions of years.

    Chapter 5 of the last IPCC report (2014 – available here) gives a good overview of what we knew then – but the field has moved on a fair bit in the last 4 years – as indeed have global temperatures.

  • But Gareth there is not one iota of evidence in IPCC 5AR that CO2 actually drives temperature. Zero. Nil. Nada.
    Most of the IPCC’s claims are based on the output of climate models, and text box 9-2 shows how poorly those models perform.
    If you have credible evidence then please cite it because no-one else seems able to.

  • “Atmospheric CO2 has just hit 410ppm, a 45% increase on pre-industrial levels”

    How far back does pre-industrial data go? I’ve not seen anything showing the magnitude or frequency of temperature FLUCTUATIONS. I have seen an average global temperature plotted over time (whether based on real data or not, I don’t know), which, of course, doesn’t show the fluctuations! If we are on a steep upwards fluctuation presently, the average won’t settle down again until some time in the future, so now it will appear to be a significant upwards trend. None of this has much bearing on whether the climate is actually changing (over a narrow band on either side of now), but it does raise some doubts about cause. At any rate, we should indeed take precautionary measures to mitigate such changes, and the most important of these is to prevent further deforestation, particularly in the tropics, but who can halt the march of economic development and “progress” across the globe? Curbing emissions is a limp-wristed token gesture, and a potential revenue source for governments (just like deforestation!)

  • There is no doubt as to the cause of the current warming. It’s CO2, and we did it. There’s plenty of argument about details – that’s the nature of scientific enquiry – but curbing emissions is by far the most important thing we can do to address the issue.

    If you would like to learn more about what we know and how we know it – rather than argue from personal incredulity – then I strongly recommend the history I link to above.

  • If there is “no doubt”, then it isn’t science! You claim that “curbing emissions is by far the most important thing we can do to address the issue”, but why isn’t halting deforestation in the tropics at least as important? On what scientific basis do you claim far greater importance for curbing emissions? The idea behind a “carbon economy” (credits, taxes, etc.) isn’t to actually curb emissions, but to make money out of big business when they decide to keep up current productivity levels by simply paying the taxes, fines, or whatever, as this will be more profitable than actually curbing emissions.

    • You appear to have a strange idea of what constitutes science. Our understanding of the physics of CO2 and radiation is at least as secure as our understanding of gravity. Basic, well-understood physics. Try reading the Discovery of Global Warming (linked above): you’ll find it very informative and interesting. Stopping deforestation is important, but not sufficient on its own to stop warming.

      Carbon pricing is explicitly designed to encourage emitters to reduce their carbon emissions. For most emitters, efficiencies in energy and carbon use bring lower costs and therefore greater profitability. It is possible to design carbon pricing that is revenue neutral (see cap & dividend schemes), though that is not always the case – but revenue generation was certainly not the prime reason why the international community began efforts to reduce carbon emissions.

  • I’m not disputing the simple idea that more CO2 + solar radiation = higher average global temperatures. But that is not “climate change” in the context here. Equally as simply, fewer plants = more CO2. I dispute the idea that we can all just reduce emissions and all will be well. Can you say how much CO2 a square kilometer of tropical rainforest can sequester per year? As I understand it, carbon sinks are actually quite difficult to predict and may be in some surprising places rather than others. This is the planet’s natural buffer against too much CO2.

    “Carbon pricing is explicitly designed to encourage emitters to reduce their carbon emissions”
    and implicity designed to generate revenue for governments when the emitters choose to maintain current levels of carbon emissions! This will be particularly true in the developing world.

    “It is possible to design carbon pricing that is revenue neutral …”
    Possible perhaps, but will it happen?