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. []

Hiatus to end soon

Not that hiatus. That never happened in the first place. No, the hiatus in posts here at Hot Topic.

It’s three months since Jim Renwick’s demolition of Guy McPherson’s enthusiastic doom-mongering, and I have been remiss in not following up with more topical observations. It’s not as though there’s any shortage of stuff to write about. I shall have more to say soon — not least because the end of April will mark the 10th anniversary of this little climate blog — but in the meantime, please talk amongst yourselves…

Guy McPherson and the end of humanity (not)

Is climate change going to wipe out humanity over the next 10 years? Prof Jim Renwick doesn’t think so…

Ecologist Guy McPherson has been touring New Zealand for the past couple of weeks, explaining why humanity has only 10 years to live (a kind-of Ziggy message that has immediate appeal to me). After his appearance on the Paul Henry breakfast show, I was called by TV3/Newshub for comment. Based on my understanding of climate change science I said that though the situation is very serious — dire even — extinction in 10 years is not going to happen. When I gave my remarks to Newshub, I knew little about McPherson but I understood that he is a very knowledgeable biologist who should not be dismissed lightly.

So, what’s the story? Is McPherson right? Is the IPCC woefully conservative and keeping the truth from us all? I had the opportunity to hear Prof McPherson speak in Paraparaumu on Saturday (Dec 10th) to get more insight into what his views really are. It was a very interesting presentation, and a very interesting discussion with the audience of 50-odd Kāpiti coasters who showed up to hear him. As the old saying goes, extraordinary claims require extraordinary evidence. What we heard was extraordinary for sure, but was not too convincing in terms of evidence.

Continue reading “Guy McPherson and the end of humanity (not)”

Global sea ice in uncharted territory

The big heat of 2016 is taking its toll on sea ice at both poles

For the past couple of months, global sea ice extent (Arctic plus Antarctic) has been at record low levels. The way the northern and southern seasonal cycles add up, the maximum in global sea ice extent occurs on average in early November, at around 27 million km2. This year, the global extent curve has been relatively flat since June. In past years, climate change “deniers” have pointed to the global extent curve as a way of claiming that climate change is not a problem, as the relatively high Antarctic extent was partly offsetting the Arctic loss, making it look as though nothing much was changing. Strangely enough, we’ve heard nothing from the usual “deniers” this year! Through most of November, there has been around 4 million km2 less sea ice than normal globally (peaking at 4.5 million on 20 November), an area roughly the size of Greenland missing near each pole. What’s going on? Continue reading “Global sea ice in uncharted territory”

This year can’t end fast enough

I sat down to write a piece looking at recent depressing climate news, and the diminished prospects of significant  US climate action now that Trump is on his way to the White House. I may still: but then I heard the news that Leonard Cohen had died and the will to wax analytical left me. This has been a pig of a year in so many ways — from Bowie, Prince and Cohen, to Brexit and Trump. In memory of one of the greatest songwriters of the last 100 years, here’s one of my favourite Laughing Len tunes, in a 2014 live performance. He was 80 at the time. I hope I have half his vitality if I get that far…

Treat this as an open thread…