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Bureau caught in own tangled web of homogenisation

By Jennifer Marohasy - posted Monday, 15 September 2014

The Australian Bureau of Meteorology now acknowledges that they change the temperatures at most, if not all, the weather stations that make-up the official station network from which national temperature trends are calculated. Indeed, earlier in the week, 28 pages of 'adjustments' were released online following a series of articles inThe Australian and The Weekend Australian by Graham Lloyd. Scrutinise the detail in this document of adjustments and not only is the rationale and methodology indefensible, but it contradicts information published in the official Station Catalogue which is meant to be the go-to document for understanding this official network known as ACORN-SAT (Australian Climate Observations Reference Network –Surface Air Temperature).

That the Minister has not yet intervened, and that many within the Australian scientific community attempt to justify the practice of homogenisation that creates these 'adjustments' that changes cooling trends to warming trends at a whim, is reason for national shame. It all amounts to corruption of the scientific process on a grand scale, with significant economic implications. But not even a whisper about the scandal can be heard from the Australian national broadcaster or the many other typically righteous institutions and individuals that claim to be motivated by the truth.

Yet the deceit is increasingly in plain view. Consider, for example, that the official ACORN-SAT Station Catalogue clearly states on page 6 that in the development of the temperature record for Bathurst Agricultural Research Station (Station No. 063005) data from the longer Bathurst Gaol (Station No. 063004) record was not used. Now go to the 28-page ACORN-SAT Station Adjustment Summary and it lists eight occasions when the Bathurst Gaol record was used to make changes to the Bathurst Agricultural Station Record, which cumulatively have changed the temperature record by 4.65 degree Celsius in different directions at different times.


Also note amongst the changes made to this temperature series the addition of 0.6 degree C to the maximum temperature series (applied to all data prior to 1971) following the installation of a Stevenson screen. That's right. While the Bureau has been claiming it must discard all data prior to 1910 because until this year stations didn't have Stevenson screens, in fact we can now see that Stevenson screens were being installed as late as 1971. Furthermore, data for decades before this time was incorporated into the official record from the Bathurst Agricultural Station even though it had a non-compliant screen.

Moving across the border into Victoria: the Bureau released the 'adjustments' used to homogenise the temperature series from the Agricultural Station at Rutherglen (also part of the ACORN-SAT network) about a week earlier than for everywhere else. This followed the series of articles in The Australian newspaper questioning why a cooling trend in the original record from Rutherglen had been turned into a warming trend in the official record.

Ken Stewart has already attempted to use the data for Rutherglen that was released last week to understand how and why the Bureau homogenised the temperature series at Rutherglen. After several days work he came to the conclusion that either the wrong list of 17 stations (against which the Bureau claimed it has made comparisons) was provided and/or their percentile-matching algorithm produced an error. In short, the method when applied as per the newly provided information produces an altogether different result to that documented by the Bureau, at least for Rutherglen.

But why even bother with the homogenisation when there was no good reason in the first place to apply it to Rutherglen?

After Graham Lloyd first brought the issue of homogenisation at Rutherglen to the nation's attention the Bureau replied that the process had needed to be applied because there had been a site move. But it has since been unable to provide any evidence, and the claim contradicts its own station catalogue.

It is the case that when weather stations are moved, for example, from post offices to airports, discontinuities can be created in the data that may need to be corrected. But in fact there is no evidence to suggest that the weather station at Rutherglen has ever moved. For the last 100 years it has been sitting in a flat paddock, creating a near perfect temperature series. In fact, all that seems amiss with the temperature series is that the minimum temperatures show a cooling trend, contrary to global warming theory.


Statistician David Stockwell had tested the original minimum temperature series for Rutherglen for discontinuities and found none. Agronomist Bill Johnston has run his own very fine-scaled 'ruler' over the same dataset and found step-changes that could be attributable to shifts in the climate, the equipment or something else. But nevertheless when all of these micro-lumps and bumps are accounted for, Dr Johnston concludes that the residual trend is no different to zero-trend. In other words, no need to make any adjustments.

Drs Stockwell, Johnston and myself have all been called deniers by the mainstream climate science community for drawing attention to the logical inconsistencies obvious in the homogenisation of Rutherglen. But at the same time none of the same name-calling scientists, who draw a government salary for their apparent expertise in this area, have been prepared to actually mention the word 'Rutherglen' in public – let alone discuss the data.

I've come to the conclusion that those who have so far defended the homogenising of the temperature series at Rutherglen, Amberley, Deniliquin and Bourke, as the first example that I have thrown up over the last few weeks, are acting either on faith, ignorance or the new morality being preached by technocrats who believe it is wholly legitimate to change received evidence when it does not accord with theory. In the case of the Bureau it's called homogenisation. Ansley Kellow in his book Science and Public Policy refers to the phenomenon as noble cause corruption.

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About the Author

Jennifer Marohasy is a senior fellow with the Institute for Public Affairs.

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