Tag: David Wratt

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. [↩]

Leyland and Carter: the rebuttal that isn’t and the hypocrisy that is

CarterFlatEarth.jpgSciblogs editor Peter Griffin recently gave climate denial activists Bryan Leyland and Bob Carter a “right of reply” to my post pointing out the errors and inconsistencies in a Dominion Post op-ed penned by the pair. Griffin took this action because of vociferous complaints from Leyland, who took offence at my discussion of his expertise (non-existent) and history of campaigning against action on climate. The result is billed as a “rebuttal”, but it isn’t, as I shall demonstrate.

The Sciblogs “rebuttal” is a mishmash of a so-called “fully referenced” version (pdf) of the op-ed that Leyland says was supplied to the Dominion Post, but he and Carter also prepared a very long-winded “response” (pdf) to the debunking of their piece by David Wratt, Andy Reisinger and Jim Renwick in the DP. The latter is a real eye-opener…

Life is too short to do another point-by-point demolition1, so I’ll select a few key issues that demonstrate that although they claim to be discussing science in a scientific manner, what they are actually doing is having the equivalent of an argument in a pub — prepared to say anything if they think it will help them “win”.

Continue reading “Leyland and Carter: the rebuttal that isn’t and the hypocrisy that is”

  1. Leyland & Carter may be retired, with nothing better to do than promote their crank viewpoints, but I have grapes and truffles to nurture through to harvest, and a book to write [↩]

DomPost denier debacle: science has the last word

The Dominion Post, which blotted its editorial copybook last week by publishing a factually incorrect and highly misleading opinion piece by climate denialists, has today published a heavyweight reply by three of NZ’s top climate scientists — David Wratt, Andy Reisinger and Jim Renwick1. Headed “Human role in climate change is clear”, the article is clear about climate reality:

Human influence on the climate system is clear and growing, and impacts are evident on all continents. If left unchecked, climate change will increase the likelihood of severe, pervasive and irreversible impacts for people and ecosystems.

We do have options to reduce risks by reducing greenhouse gas emissions and adapting to some climate change, but time is running short if we want to limit changes to manageable levels. Ignoring or misconstruing the overwhelming evidence is not a responsible risk management strategy.

It’s not clear whether the DomPost plans any further response to the rubbish they printed from Bryan Leyland and Bob Carter, but the editorial team at the newspaper would do well to reflect on the approach to the subject adopted by Guardian editor Alan Rusbridger, introducing an important new series of features in that paper:

For the purposes of our coming coverage, we will assume that the scientific consensus about man-made climate change and its likely effects is overwhelming. We will leave the skeptics and deniers to waste their time challenging the science. The mainstream argument has moved on to the politics and economics.

Precisely. Rusbridger — who is retiring after 20 years as editor — wants his newspaper to do justice…

…to this huge, overshadowing, overwhelming issue of how climate change will probably, within the lifetime of our children, cause untold havoc and stress to our species.
So, in the time left to me as editor, I thought I would try to harness the Guardian’s best resources to describe what is happening and what — if we do nothing — is almost certain to occur, a future that one distinguished scientist has termed as “incompatible with any reasonable characterisation of an organised, equitable and civilised global community”.

That’s what a real newspaper does: takes on the big issues. If the Dominion Post wants to be more than a Noddy book newspaper publishing rubbish from the intellectual heirs to Big Ears, it’s high time it took a sensible approach to the climate debate, and followed Rusbridger’s lead.

Continue reading “DomPost denier debacle: science has the last word”

  1. David Wratt is an Emeritus Climate Scientist at NIWA, an Adjunct Professor in the NZ Climate Change Research Institute at Victoria University, and a Vice Chair of Working Group 1 of the IPCC. Andy Reisinger is Deputy Director (International) of the New Zealand Agricultural Greenhouse Gas Research Centre and served as coordinating lead author in the most recent IPCC report. James Renwick is a Professor of Physical Geography at Victoria University of Wellington and served as a Lead Author on the last two IPCC Reports. [↩]

Stocker in Wellington: RSNZ to stream AR5 science workshop

Swiss climate scientist Thomas Stocker, joint chairman of the IPCC’s Working Group One, is in New Zealand for a few days, and the NZ Climate Change Centre and the Royal Society of NZ have taken the opportunity to put together a stakeholder workshop to allow Stocker and NZ lead authors to present the key findings of the recently published AR5 WG1 report. The workshop is being held tomorrow, Friday 11th, from 9am to 1pm at the RSNZ in Wellington, and is open to the public (spaces limited, register here). For the geographically challenged, the event will be web-cast live.

The workshop will open with an introduction by Richard Bedford, a council member of the RSNZ, and an overview of the IPCC process by WG1 vice-chair David Wratt. Stocker will present the key Working Group I report findings from about 9-10am. NZ’s coterie of lead authors — Dave Frame, Tim Naish, and Jim Renwick — will provide snapshots of the parts of the report they were involved with. From midday on, the Science Media Centre’s Peter Griffin will chair a “stakeholder panel” including Rod Oram, Federated Farmers vice-chair William Rolleston and Frances Sullivan from Local Government NZ to discuss how the report has been received and what it means for New Zealand.

Stocker is also being interviewed by Radio NZ National’s science correspondent Veronika Meduna, and that should be broadcast in her show next week.

Stormy weather: we’re making it worse, and there’s more on the way

The IPCC released the summary for policymakers of its Special Report on Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation (SREX) in Kampala, Uganda, on Friday (SPM, SREX site, launch presentation slides). The report concludes that globally there has been a significant decrease in cold days and nights and an overall increase in warm days and nights, that it’s likely that “anthropogenic influences” have led to warming of extreme daily minimum and maximum temperatures, and that heavy rainfall events are increasing in many areas. There has also been an increase in extreme coastal high water events.

The report also projects that it is “virtually certain” that increases in the frequency and magnitude of warm daily temperature extremes will continue through this century, and that there will be corresponding decreases in cold extremes. It’s also very likely that heat waves and warm spells will become more frequent and warmer. Heavy rainfall events are also expected to increase, and the proportion of rain falling in those events is likely to increase. There are also likely to be more problems from storm surges and sea level rises, an increase in droughts, and landslides in mountainous regions.

Continue reading “Stormy weather: we’re making it worse, and there’s more on the way”