Rel over Australische temperatuurmetingen

Jennifer Marohasy: Afkoeling wordt opwarming.

De Australische klimaatsceptica, Jennifer Marohasy, stelde vast dat in Australische temperatuurreeksen van verschillende locaties afkoeling in de ruwe data, na correctie / homogenisering, veranderde in opwarming (zie afbeelding hieronder). Zij kon daarvoor geen verklaring vinden. Dit wekte haar achterdocht.

Onder de titel, 'Cooling turns to warming', rapporteerde Graham Lloyd daarover het volgende in 'The Australian':

The [Australian] Bureau of Meteorology [BOM] has been accused of manipulating historic temperature records to fit a predetermined view of global warming.

Researcher Jennifer Marohasy claims the adjusted records resemble “propaganda” rather than science.

Dr Marohasy has analysed the raw data from dozens of locations across Australia and matched it against the new data used by BOM showing that temperatures were progressively warming.

In many cases, Dr Marohasy said, temperature trends had changed from slight cooling to dramatic warming over 100 years.

BOM has rejected Dr Marohasy’s claims and said the agency had used world’s best practice and a peer reviewed process to modify the physical temperature records that had been recorded at weather stations across the country.

It said data from a selection of weather stations underwent a process known as “homogenisation” to correct for anomalies. It was “very unlikely” that data homogenisation impacted on the empirical outlooks. ...

Dr Marohasy said she had found examples where there had been no change in instrumentation or siting and no inconsistency with nearby stations but there had been a dramatic change in temperature trend towards warming after homogenisation. .

Aldus Graham Lloyd

Lees verder hier.

Onder de titel, 'Heat is on over weather bureau ‘homogenising temperature records’', gaat Jennifer Marohasy op haar eigen blog verder op deze zaak in.

Lees hier.

De reactie van het Australische KNMI (BOM) bleef dit keer niet uit. In het verleden was op verschillende verzoeken om nadere informatie niet gereageerd. Maar nu dus wèl! Zou het feit dat de politieke wind in Australië nu uit een andere hoek waait daar iets mee te maken kunnen hebben?

Maar voor een andere Australische klimaatsceptica, Jo Nova, was de verklaring toch niet bevredigend. Onder de titel, 'BOM finally explains! Cooling changed to warming trends because stations “might” have moved!' schreef zij onder meer op haar blog:

It’s the news you’ve been waiting years to hear! Finally we find out the exact details of why the BOM changed two of their best long term sites from cooling trends to warming trends. The massive inexplicable adjustments like these have been discussed on blogs for years. But it was only when Graham Lloyd advised the BOM he would be reporting on this that they finally found time to write three paragraphs on specific stations.

Who knew it would be so hard to get answers. We put in a Senate request for an audit of the BOM datasets in 2011. Ken Stewart, Geoff Sherrington, Des Moore, Bill Johnston, and Jennifer Marohasy have also separately been asking the BOM for details about adjustments on specific BOM sites. (I bet Warwick Hughes has too). The BOM has ignored or circumvented all these, refusing to explain why individual stations were adjusted in detail.

The two provocative articles Lloyd put together last week were  Heat is on over weather bureau  and  Bureau of Meteorology ‘altering climate figures, which I covered here. This is the power of the press at its best. The absence of articles like these, is why I have said the media IS the problem — as long as the media ignore the BOM failure to supply their full methods and reasons the BOM mostly get away with it. It’s an excellent development The Australian is starting to hold the BOM to account. (No sign of curiosity or investigation at the ABC and Fairfax, who are happy to parrot BOM press releases unquestioned like sacred scripts.)

The BOM rely on the usual vague wordy explanation with the unscientific reasoning that homogenization is necessary according to “international literature”. (I guess there is a consensus then, and we all know what that’s worth.) It is the scientific equivalent of saying  “we’re experts — trust us”. No one would accept that from a company accountant, why from a scientist?

Voorts gaat zij gedetailleerd in op de verklaring van de BOM van de aanpassingen van de metingen van de betrokken stations. Zij concludeert:

In all three cases above the BOM tacitly admitted Jennifer Marohasy has the calculations of the trends right, and the massive changes from raw to adjusted really happened. In all three cases the weasel words “likely”, “consistent” and “may” are used with speculative undocumented reasons for changes. How are imagined and unrecorded site moves “consistent” with the definitive certainty of headlines like “hottest ever year”?  Next time we’re told it’s another warmest September night in East Where-ever, will we hear that it’s a tenth of a degree warmer, but only according to a bunch of homogenized, adjusted thermometers which may have been 300 km away? Will anyone mention that warmer nights were reported in newspapers of the day, but they were discovered to be wrong 70 years later?

Aldus Jo Nova.

Lees verder hier.

En hoe zit het in Nederland? In een oud dossier van klimaatscepticus (wijlen) John Daly trof ik onderstaande grafiek (tweede afbeelding) van de temperaturen van De Bilt aan, die op soortgelijke wijze waren aangepast. Raadselachtig! Want de temperatuurmetingen in De Bilt hebben internationaal een ijzersterke reputatie wat betrouwbaarheid betreft. Kan iemand daarvoor een verklaring geven?

[Naschrift

Onder de commentaren geeft Gerbrand Komen (voormalig directeur wetenschappelijk onderzoek KNMI) een antwoord op die vraag.]

Voor mijn eerdere DDS–bijdragen zie hier.