The Australian Temperature Record- Part 5: Tasmania

Ken Stewart, June 2010

STOP PRESS-  new graph added below

Tasmania is Australia’s smallest state, the Apple Isle.  It’s the home of Tasmanian Devils, the only State government with the Greens in coalition, and some interesting climate data.

The Australian Bureau of Meteorology (BOM) develops its climate Trend Maps and Time Series graphs form 100 sites nationwide, comprising the High Quality Australian Site Network.  Five of these are in Tasmania. 

Here is a map of the sites:

Here’s the Trend Map

And Time Series Graph:

As you can see, BOM declares a warming trend of 0.08C per decade, or 0.8 degrees C for the last 100 years.

I am engaged in a fairly lengthy study of the High Quality Australian Site Network, and as part of that project have analysed the data from the Tasmanian sites.  I averaged maxima and minima for all stations at each site, then compared with the High Quality means.  A spokesperson for BOM has asserted that: 

“On the issue of adjustments you find that these have a near zero impact on the all Australian temperature because these tend to be equally positive and negative across the network (as would be expected given they are adjustments for random station changes).”

Here are the results. 


40.3% , even 33.3%, warming bias is significant in anyone’s language.

Graph of the size of the adjustments

Note that two stations’ trends are essentially unchanged, one is cooled, and two have strong warming adjustments.  Let’s look at these records.

Low Head:


Cape Bruny Lighthouse:


King Island Airport (Currie):


Strahan Aerodrome:  This site has records only from 1982 and 1983, and from 1992.  So the record can only be constructed by splicing Cape Sorrel (14km away) Vivian St, and The Lodge.

Note the declining trend in the closed site data.  Now here is the homogenised data:

-0.2 changed to + 0.5! How does that work?  You may be interested to know that BOM is not supposed to use data from stations over a mountain range.  It couldn’t have been from Zeehan 29.5km away as it shows even more cooling!


2 diverging records.  The earlier one is from the Pump Station (not PO).  How do you get a trend from that?  Especially as Launceston Airport is listed by Torok (1996) as Urban, and should not have been used.  The only way is to splice the Pump Station data with the airport is by reducing the earlier figures by 1.2 degreesC.

0.1 degrees adjusted to 0.9!  

Update:  here’s a graph of the raw mean of all stations for each year and the HQ mean:

Tasmania’s Raw data mean trend:  0.5 degrees C per 100 years

Tasmania’s High Quality mean trend: > 0.75 degrees C!


Two of Tasmania’s five stations (40%) have been adjusted to the extent that Tasmania’s High Quality temperature has a warming bias of 40%. 

When the mean of all stations annual means (raw and HQ) are graphed, there is a warming bias of at least 50%.

These adjustments, and the Australian temperature record to which they contribute, are plainly not to be trusted.

Progress report on the Australian High Quality Site Network:

Sites checked:             70  out of 100

Raw trend:                  +0.79 degrees C/ 100 years

High Quality trend:     +0.99

Average difference:    +0.20

Warming bias:           24.86%

There will have to be a massive cooling bias in the remaining 30 stations to return the overall Australian adjustments to neutral.

I gratefully acknowledge the assistance of Lance Pidgeon in downloading data for this post.  Thanks mate!


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