What warming?Richard Treadgold | August 6, 2011
NIWA’s data confirms: little warming
When it’s calculated correctly
Why did they lie to us?
In December last year, NIWA released their long-awaited review of the NZ temperature record (NZTR). We’ve reviewed that report and found serious errors. NIWA used the wrong method and created strong warming. We used the right method and found mild warming.
There are a few things we need to understand about weather stations. The first is that these stations sit there for a long time. Some of them have been in the same place for 80 years and more. If you sat in one place for that long, you’d see stuff happening around you — same for the weather station.
Trees grow, buildings go up, airport runways get covered in tarseal or concrete, roads appear, and these and other non-climatic influences affect the temperature readings, usually making them warmer, but not always. Sometimes the station gets moved, and it’s always better to keep all that history if you can, so you try to adjust it rather than start again with a new station.
NIWA had to start from scratch
Knowing this, when scientists examine a series of temperature readings they look for what has changed at the different stations. If the changes affected the temperature readings, they adjust the readings.
When we and the Coalition asked NIWA in November 2009 for the adjustments they had made, this was what we were asking for — a list of all the individual changes and the reasons for them. We wanted to independently review them. In the end, they didn’t have that information any more so they had to start from scratch with a brand-new report. That’s what they released just before Christmas and we’ve been reviewing it since then.
Our scientists have now completed their audit and released their findings. They report a number of serious errors in NIWA’s review. They are summarised here, but the details are available in the official Coalition report (see details below). Some of the errors are a bit complex, but the worst of them is very simple: NIWA didn’t do what they claimed.
There is nothing trivial about this failure — it’s not about cosmetics, company image or merely using the wrong typeface — this is a fundamental failure, either of method or communication.
NIWA heavily criticised us for not knowing the methodology used in the original Seven-Station Series (7SS), but now it turns out that they haven’t used it themselves.
There’s plenty wrong with the new NZTR
NIWA stated repeatedly before they undertook the reconstruction that they would use the adjustment methodology specified in Rhoades and Salinger, 1993 (R&S), and Wayne Mapp, their Minister, gave the same assurance in answer to Parliamentary questions. NIWA’s paper itself reinforces the point by making reference to R&S throughout its 169 pages.
But the mathematics is unmistakable: NIWA did not correctly use the R&S method to make the adjustments. Instead, they went way outside the requirements of R&S, changing the method in ways that strongly changed its results. Their changes created a trend that overstates the New Zealand warming over the past hundred years by 168%.
The R&S method calls for comparisons to be made only between “neighbouring” stations, but in another mistake NIWA uses Dunedin and Dargaville to fill gaps in the data at Albert Park, though they are more than 1100 km apart across several mountain ranges and lie on opposite coasts.
Then, NIWA wrongly uses stations known to be affected by the Urban Heat Island (UHI) effect, which introduces a spurious warming, and makes no adjustments to remove it.
- Monthly data – R&S clearly requires the use of monthly data, but NIWA uses annual data.
- Symmetric interval centred on the shift – R&S specifies data from a symmetrical period, but NIWA sometimes uses asymmetrical periods.
- A 1-2 year period before and after the shift – Where R&S requires just one or two years, NIWA uses variable periods of up to 11 years. This can introduce unwanted climatic factors.
- Weighted averages based on correlations with neighbouring stations – NIWA ignores the R&S requirement to weight the averages according to the correlation with neighbouring stations.
- Adjustments only performed if results are significant at the 95% confidence level – NIWA seems to perform all adjustments — there’s no evidence of any significance tests.
Sequence of events
Late in November 2009, the Climate Conversation Group helped to produce, in collaboration with the NZ Climate Science Coalition, Are we feeling warmer yet? a report that some called Niwagate.
The report examined the database of temperature records on NIWA’s web site and asked the reasons for unannounced adjustments we found that NIWA had made to the raw temperature readings from around New Zealand.
It soon became apparent that NIWA were unable to answer our questions; they had lost records, or they never kept records; they delayed, they blustered, they criticised the Coalition, they obfuscated and, most egregiously of all, they pointed us to non-existent references to the scientific methodology which took several of our scientists (volunteers all) many hours to discover were useless.
We just wanted to know why they adjusted the temperature records. The way they squirmed, you would have thought it was a matter of state security. In the end, it transpired they no longer had the information. Why didn’t they just say so?
After continued questions in the Parliament from the ACT party, in February 2010 NIWA provided an “example” set of adjustments to the Hokitika records. A week later they announced they would “reconstruct” the entire New Zealand temperature record. It would take several months and cost about $70,000. This was a victory for the persistence of the Coalition and for all New Zealanders who thought that so simple a thing as the public temperature record should be properly scientific.
A public temperature record beyond dispute?
Do we have a NZTR which is finally beyond dispute? No, we’ve found too much wrong with it. The new disputes are just beginning. This NZTR is excruciatingly awful. If there’s any whisper that this unscientific fiasco has influenced the wider picture in the Pacific or even the globe, we’ll be demanding it be corrected.
There’s a strong possibility that the NZTR has been used across a wide swathe of the Pacific Ocean, falsely inflating temperatures for a large region.
Everything depends now on what NIWA does next. Will they admit to their mistakes? Will they make things right? Will they, like last time, underestimate their opponents and try to fight their way out?
Or will they confess to prefer being corrected than continuing in error? They are an organisation which does a whole lot of good things in New Zealand and it would be a pity to see their reputation soiled by a piece of inept or unethical work.
The Coalition asks for the suspension of the new NZTR until it can be corrected. I would go further and expect whoever made the misguided decisions that resulted in the faulty NZTR to resign from NIWA.
Who lied to NZ public?
Who decided to make substantive changes to the R&S method and lie about it to the New Zealand public? That person should not have a senior role in a reputable organisation.
What now for NIWA’s supporters?
NIWA has enjoyed tremendous support in our dispute with them. Much has been written about it and much obloquy heaped on my and my Coalition colleagues’ heads. This scientific review of NIWA’s report provides justification for our initial scepticism and our perseverance. Seeing what this audit reveals, it’s hard to find reasons to support NIWA.
At first, we hinted strongly at malpractice, to goad the ever-languid NIWA scientists into releasing the data they had withheld for many years. Our goading eventually succeeded in prompting the reconstruction of the NZTR.
Examining the results of that work has uncovered stronger evidence of unscientific and even possibly unethical behaviour than we ever imagined. We certainly never hoped for this. To clarify: this does not please us. We never wanted to find evidence of dishonesty, never imagined that we might and we are disappointed to discover that they failed to do what they said.
Where to get the documents
NIWA released their review document, containing an overview and reports for each individual station in the New Zealand Temperature Record (NZTR), just before Christmas last year. It had been peer-reviewed by the Australian Bureau of Meteorology. You can download those documents as pdf files from the NIWA site. Here’s the overview document.
You can download the official NZCSC audit of NIWA’s review, Statistical Audit of the NIWA 7-Station Review (pdf, 2.7 MB).
There’s a sizeable Supplementary Information document, Statistical Audit of the NIWA 7-Station Review SI (pdf, 6.2 MB), to go with it. It contains the material for the other six stations in the NZTR.
One of the principal messages to be taken from this audit of NIWA’s new NZTR is that New Zealand has seen no temperature rise from global warming so far, and we can expect none in the foreseeable future. A seminal paper from the Coalition’s Chairman, Barry Brill, entitled New Zealand Unaffected by Global Warming, describes the research and its conclusions — handy for students (pdf, 1.3MB).