The final cut: crank paper on NZ temperature record gets its rebuttal – warming continues unabated

At last: the curtain falls on the final act in the case of NIWA versus the NZ climate cranks. de Freitas et al (2015) – which purported to show warming in NZ was much lower than previously calculated – is shown to be comprehensively wrong in a new paper by NZ’s top temp experts.

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. []

Pocket calculator

homer.jpgThe National Institute for Water and Atmospheric Research (NIWA) has bought a shiny new supercomputer. For $12.7m they’re getting a IBM Power 575 that will be the fastest climate machine in the southern hemisphere, 14th fastest in the world — and it will get an upgrade in 2 years which will double its speed. Sounds like a good deal to everyone but NZ’s climate cranks. Bryan Leyland, “chair of the economics panel” of the NZ CSC rushed to issue a press release:

“It is a national scandal that NIWA are squandering $12.7 million of taxpayers’ hard earned money on yet another supercomputer. In spite of buying a Cray T3A supercomputer several years ago, their predictions of the climate have been spectacularly wrong. They failed to predict the 1998 El Nino event, the cooling that has been noticeable since 2002 and the increased cooling that has been recorded over the last two years.”

A NIWA spokesman was quick to point out that they bought the Cray in 1999, so would have been hard-pressed to use to it predict an El Niño in the preceding year, but Leyland’s outburst is mainly interesting for two reasons: it’s an amusing public parade of ignorance (a bit like standing in the middle of Wellington wearing a dunce’s hat shouting “Look at me!”), and because he recommends that NIWA give up climate modelling and instead rely on the work of a British forecaster called Piers Corbyn. Let’s start with Leyland’s take on climate models.

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You can’t Hide (your policy from me)

rodenymorph.gifA few months ago, Rodney Hide decided that he and his party had little to lose and votes to gain by declaring themselves to be climate sceptics. I’ve roundly criticised this stance in earlier posts, and this week I’ve been joined by The Listener‘s Ecologic columnist Sarah Barnett, who takes Hide to task here (full text available next week). With the election approaching, it’s time to dig a little deeper into the intellectual foundations of ACT’s climate change policy, such as they are.

The ACT web site now features a policy document [PDF], and a background briefing [PDF] on their policies page. Let’s take a detailed look…

Continue reading “You can’t Hide (your policy from me)”