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). []
  4. Jim is currently a visiting professor at the Department of Geography and Environmental Studies, University of Haifa, Mt Carmel, Israel. []

Too hot (and here comes the surge)

GISS20152015 was the hottest year since records began in all of the major global temperature datasets, and by a huge margin. The world is now more than 1ºC warmer than pre-industrial temperatures — pushed there by rapidly rising levels of greenhouse gases in the atmosphere, and helped a little by the current very strong El Niño. And because El Niño’s major impacts on global temperatures happen as an event declines, we can expect 2016 to be even warmer.

Carbon Brief has an excellent analysis of the new record here. See also NASA and NOAA’s joint announcement, the NASA press release, and Hansen et al’s overview (pdf). Here’s the latter on the outlook for the rest of the decade:

We can also say with confidence, because of Earth’s energy imbalance (energy absorbed from sunlight exceeding heat radiated to space), that the present decade will be warmer than last decade. Already the first half of the present decade is almost 0.1°C warmer than last decade. Strong La Niñas commonly follow strong El Niños, so it is likely that 2017 and perhaps 2018 will be quite cool relative to 2015-2016, but the decade as a whole should be considerably warmer than the prior decade.

Kevin Trenberth provides an interesting overview at The Conversation, detailing some of the weather extremes delivered by the current El Niño, and notes:

What we have seen this past year will likely be routine in about 15 years, although regionally the details will vary considerably. Indeed, we have had a glimpse of the future under global warming.

You wouldn’t want to bet against it continuing… Continue reading “Too hot (and here comes the surge)”

Heat: 2014 breaks global temperature records, 2015 could be hotter


Last year was the warmest year on record for the planet, analyses by NASA and NOAA show, and it’s possible that 2015 could be warmer still. 2014 was warmer than previous record holders 2005 and 2010, and comfortably ahead of 1998. 13 of the hottest 15 years on record have all occurred since 2000. Remarkably, 2014’s warmth was achieved without much assistance from an El Niño — which boosts global temperatures and is normally a factor in record setting years, as this graphic from Skeptical Science shows:

ENSO Temps static480

For more discussion of ENSO’s impact on temperatures, see Dana Nucitelli’s article at The Guardian, and Jim Hansen et al’s discussion here. Hansen warns that more warming could be on its way:

More warming is expected in coming years and decades as a result of Earth’s large energy imbalance, more energy coming in than going out, and with the help of even a mild El Niño 2015 may be significantly warmer than 2014.

The risk of further rapid rises in global temperatures could also be increased by early signs that the Pacific Decadal Oscillation (PDO) may be shifting to its positive phase, as the Peter Hannam at the SMH pointed out late last year:

“During a positive PDO phase, you’d expect temperatures to keep climbing again as they did in the 1980s and 1990s,” Dr (Shayne) McGregor (of UNSW) said, adding that as PDOs are measured by rolling 11-year averages, it will be a while before any shift becomes clear.

In New Zealand, NIWA reports that the nationwide average temperature for 2014 was 12.8°C, 0.2°C above the 1981–2010 annual average, but that June was tied for warmest in the long term record. The MetService blog provides a good overview of regional weather here.

For further analysis and discussion, there is a lot of good coverage and supporting information available on the web. Here’s my pick of some of the best.

News coverage: New York Times (above the fold on the front page, no less), BBC, Guardian, Stuff (taking the AP coverage). Time makes the obvious point: warming continues unabated, which should give the lie to climate crank nonsense about no recent warming1.

Background analysis: the Climate Council in Australia (who created the graphic at the top of this post), a superb Bloomberg graphic, Climate Nexus, Climate Central (one and two), and for my favourite visual reminder of how warming has progressed, here’s NASA’s animation of global warming from 1880 to 2014:


  1. …but I won’t be holding my breath… []

Stuffed birds and hot years (Merry Christmas)

The fourth LP I bought (after Sgt Pepper and The Monkees first two albums — this was 1967/8, and I’d just acquired a record player that could handle discs larger than singles) was a Stax sampler called This Is Soul. It triggered a life-long love of that Memphis soul sound, and in particular the voice of Otis Redding. His version of White Christmas is a thing of joy. Play it today, and think not of the fact that this year is likely to set new records for hottest year on many of the global temperature series.

Nick Cave’s take on Christmas is (characteristically) a little gloomier than most, and perhaps more appropriate.

Things down here are fragmented

In fact they’ve exploded all over the room

I think everything’s a little off-center, babe

I do dear, I do

So, dear reader, allow me (and all the contributors to Hot Topic) to wish you the very merriest of whatever season it may be that you are currently celebrating. In the Waipara Valley it looks like it’s going to be a long hot day. A turkey is truffled and soon to be cooked, there is too much good wine to drink1, and Rosie the beagle is looking forward to a break in her post-harvest diet. Nadolig llawen.

PS: If confronted by a climate-denying family member over the holidays, here’s some advice on how to approach them, from The Conversation via the NZ Herald.

  1. Considering the supplies laid in for the next week, and my intention to have a dry January, my liver is going to take a hammering. Do not expect much in the way of posts here. []

Is earth’s temperature about to soar? (No pause, no hiatus, only warming)

This is a guest post by the statistician who blogs as Tamino, cross-posted from his Open Mind blog with his permission. It’s important reading…

A recent blog post on RealClimate by Stefan Rahmstorf shows that when it comes to recent claims of a “pause” or “hiatus,” or even a slowdown in global surface temperature, there just isn’t any reliable evidence to back up those claims.


Yet for years one of the favourite claims of those who deny the danger of global warming has been “No global warming since [insert start time here] !!!” They base the statement on the observed data of earth’s surface temperature or its atmospheric temperature. Then they claim that such a “pause” or “hiatus” in temperature increase disproves, in one fell swoop, everything about man-made climate change.

They seem a bit worried lately because it is very likely that the data from NOAA (National Oceanic and Atmospheric Administration) will record this year as the hottest on record; we won’t know, of course, until 2014 is complete. A single year, even if the hottest on record, has only a little to do with the validity of such claims, but a lot to do with how hard it is to sell the idea. Perhaps they dread the prospect that if the most recent year is the hottest on record — in any data set — it will put a damper on their claims of a “pause” in global warming. If they can’t claim that any more, it deprives them of one of their most persuasive talking points (whether true or not). Still the claims persist; they’ve even begun preparing to ward off genuine skepticism spurred by the hottest year on record.

I seem to be one of very few who has said all along, repeatedly and consistently, that I’m not convinced there has been what is sometimes called a “pause” or “hiatus,” or even a slowdown in the warming trend of global temperature — let alone in global warming.

Continue reading “Is earth’s temperature about to soar? (No pause, no hiatus, only warming)”