Open Letter from Jennifer Marohasy

Jennifer Marohasy has written to Dr David Jones, head of climate monitoring and predictions at the Bureau of Meteorology, which she has posted as an Open Letter at her blog.

She asked me to review her draft and I made a few small suggestions.

I wish her good luck with Dr Jones.  I am persona non grata with him apparently and I had to write to the Minister before getting a very unsatisfactory reply, many months later, from BOM- Jones refused to reply.  I had to follow up with the Minister again, with a copy to Greg Hunt as Opposition spokesman, before getting some requested information, and an apology.  I analysed this information here.  Promised Journal articles did not arrive at all, and after writing again to the Minister, I received a completely irrelevant paper on ACORN-SAT.  Another letter brought another reply from the next Minister, but still no substantive information I had requested.  This was in August 2012.  My first request for a response from Dr Jones was in July 2010, and my first letter to the Director of Meteorology was in October 2010.  I gave up after this.

I hope Dr Marohasy has more success than I did.


Here is her letter:

Open Letter Requesting Verification of 2013 Temperature Record

Posted by jennifer, January 9th, 2014 – under Information.

Dr David Jones
Manager of Climate Monitoring and Predictions
Australian Bureau of Meteorology

Dear Dr Jones

Re: Request Verification of 2013 Temperature Record

I am writing to request information be made publicly available to myself and others so we may have the opportunity to verify the claim made by you on behalf of the Australian Bureau of Meteorology that 2013 was the hottest year on record in Australia. In particular it is claimed that the average temperature was 1.20°C above the long-term average of 21.8°C, breaking the previous record set in 2005 by 0.17°C.

This claim is being extensively quoted, including in a report authored by Professor Will Steffen of the Climate Council, where he calls for the Australian government to commit to further deep reductions in greenhouse gas emissions because of this “record-breaking year”. Accurate climate records are not only of political interest, but are also of importance to those of us who rely on historical temperature data for research purposes. For example, the skill of the medium-term rainfall forecasts detailed in my recent peer-reviewed publications with John Abbot, have been influenced by the reliability of the historical temperature data that we inputted. From a very practical perspective, businesses will adjust their plans and operations based on climate data, and ordinary Australians worry and plan for the future based on anticipated climate trends.

Further, I note that you said in a radio interview on January 3, 2014, following your “hottest year on record” press release that, “We know every place across Australia is getting hotter, and very similarly almost every place on this planet. So, you know, we know it is getting hotter and we know it will continue to get hotter. It’s a reality, and something we will be living with for the rest of this century.”

The Australian Bureau of Meteorology is the custodian of an extensive data network and over a long period now, questions have been asked about the legitimacy of the methodology used to make adjustments to the raw data in the development of the Australian Climate Observations Reference Network – Surface Air Temperatures (ACORN-SAT). Furthermore, questions have been asked about why particular stations that are subject to bias through the Urban Heat Island (UHI) effect continue to be included in ACORN-SAT. In particular why is ‘Melbourne Regional Office’, a station at the corner of Victoria Parade and Latrobe Street (Melbourne CBD) still included in the ACORN-SAT network when this station is known to have become sheltered from previously cooling southerly winds following construction of office towers.

I understand ACORN-SAT was used to calculate the statistics indicating 2013 was the hottest year on record, but it is unclear specifically which stations from this network were used and how data may have been further adjusted in the development of the record breaking temperature anomaly.

Rockhampton-based blogger Ken Stewart, for example, has suggested that in the calculation of the annual average temperature for Australia, the eight sites acknowledged as having anomalous warming due to the UHI would not have been included. Is this the case? I had assumed that the Bureau used all 112 ACORN-SAT locations, and thus that the record hot temperature anomaly announced by you, actually includes a UHI bias.

Radio presenter Michael Smith has given some publicity to claims made by blogger Samuel Gordon-Stewart that the Bureau has overestimated the average Australian temperature by about 4 degrees. Mr Gordon-Stewart calculated average temperatures and temperature anomalies from data from all the weather stations listed by Weatherzone.

Furthermore, given many ACORN-SAT stations have continuous temperature records extending back to the mid-late 1800s and many stations were fitted with Stevenson screens by 1900, why does the Bureau only use data after 1909, all the while claiming that 2013 is the hottest year on record? Indeed it is well documented that the 1890s and early 1900s, years corresponding to the Federation drought, were exceptionally hot.

In summary, given the importance of the historical temperature record, and the claim that 2013 is the hottest year on record, could you please provide details concerning:
1. The specific stations used to calculate this statistic;
2. The specific databases and time intervals used for each of these stations;
3. The history of the use of Stevenson screens at each of these station;
4. How the yearly average temperature is defined; and
5. Clarify what if any interpolation, area weighting, and/or adjustments for UHI bias, may have been applied to the data in the calculation of the annual mean values.

Kind regards

Dr Jennifer Marohasy

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17 Responses to “Open Letter from Jennifer Marohasy”

  1. Ian George Says:

    I am at a loss regarding this as well. I ran the figures from the climate summary for NSW for December and found an interesting anomaly.
    If you average the towns listed for NSW (95 in all), the anomaly comes out at +1.36C (I have only counted those that have a listed anomaly). Yet the NSW and the National anomaly for NSW is recorded at 1.6 and 1.64 respectively.
    As you have suggested in past posts, the BOM seem to be only listing those temps in the ACORN data base.
    And, as we are aware, the ACORN data has been adjusted (mostly downwards).
    This brings into question the idea 2013 was the warmest year and I look forward to what transpires re Dr Marohasy’s request.

    • Ken Stewart Says:

      Area averaging may be the reason. BOM only use Acorn sites for climate analysis- that’s what they say anyway.
      In a climate phase where warming may be plateauing of course you will get record hot years- that doesn’t worry me at all. The BOM has an obsession with extremes apparently, and the introduction of Acorn appears to have removed a number of past extremes from several sites. But the creators of Acorn have shot themselves in the foot with their past adjustments as the record now shows no greater minima warming and no greater winter warming, directly contradicting climate models.

  2. Ian George Says:

    This is OT but couldn’t help to pass this on.
    Another ABC ‘myth’ re drought in Charleville.
    ON ABC local and now posted on Weatherzone:-
    ‘For the past year and a half Charleville has received its lowest rainfall since records began.’
    Facts are:
    June 2012 to Dec 2013 – about 378 mls.
    June 1899 to Dec 1900 – about 290 mls.
    During the Federation drought, there were 6 consecutive years of below average rainfall with 1899 being the lowest on record at 203mls.
    Prior to this drought, 2010-2012 were all above average with 2010 having the second highest rainfall since the 1880s (1133mls).
    How do you get that onto the ABC Watch blog?

  3. wazsah Says:

    Ian, have you got a URL for exactly what weatherzone says – I can not see it there.

  4. wazsah Says:

    Ian, I pulled the monthly data for Charleville PO 44022 from the BoM here –
    All years from 1881-1959 and a few earlier from 1874.
    It looks as if plenty of 18 month periods from 1 July to 31 Dec had lower than 378mm rain.
    July 1875 to Dec 1876 – 326.8mm but too many 0 months
    July 1898 to Dec 1899 – 266.7mm
    July 1899 to Dec 1900 – 290.3mm
    July 1901 to Dec 1902 – 372.9mm
    July 1928 to Dec 1929 – 314.7mm
    July 1937 to Dec 1938 – 364.7mm
    July 1945 to Dec 1946 – 367.1mm
    Even the BoM decile map here has Charleville plotted outside the “Lowest on Record” contour

    I wonder how this got into the ABC news items in the first place and then did Weatherzone repeat it without checking ?

  5. Ian George Says:

    Here at:
    And here for the ABC story

  6. Ian George Says:

    Thanks waszah
    Now how do you get that info onto ABC News Watch or Fact Finders?
    I also see they’re attacking the ABC (at News Watch) over Canberra’s recent heatwave – Jan 1939 was hotter.
    The Canberra data at ACORN only goes back to March 1939 – very convenient.

  7. Mike R Says:

    Unfortunately the calculations. referred to in Dr Marohasy’s letter above, by Samuel Gordon-Stewart are totally misleading. The difference between his results and the Bureau of Meteorology (-4 degrees C) can be readily reconciled by considering the distribution of stations used for his calculations. His averages included a huge bias towards cooler stations (i.e. in his spreadsheet. the number of Tasmanian sites is approximately the same as that for the Northern territory!. What was Samuel thinking?).

    To his credit Samuel has done a lot of work accruing this data and his link to his spreadsheet at his blog allows others to review and scrutinize his primary data. I wish all the other bloggers purporting to show some novel insight into climate change debate, especially those who criticize the BOM for lack of transparency, would do likewise.

    Samuel has also kindly added my comments at the conclusion of his blog (despite it contradicting his results) that supports the BOM version of the temperature record for 2013. I respect him for this. This corrected version of Samuel’s spreadsheet which significantly reduces the bias is now included in the last comment of the blog entry (see

    This episode illustrates the misunderstandings that can lead to the enduring myths and Machiavellian conspiracy theories that propose that the BOM has manipulated the data either consciously or unconsciously via ‘group think’.

    With respect to ‘group think’, it is incredible that a single determined blogger with, I suspect very little training in scientific data analysis, and armed only with a spreadsheet can produce such a ridiculously large discrepancy of 4 degrees and still be given credibility by Dr Marohasy, . And to think no one else at the bureau, or even those obsessional bloggers who scrutinize every temperature entry, would not have noticed a 4 degree discrepancy? Half a degree maybe, even 1 degree but 4 degrees is pushing things into the realms of fantasy.

    In summary this an example of ‘group think’ or just wishful thinking at it’s worst. Maybe group delusional thinking is a more appropriate description.

  8. johnnicol Says:

    As Ken Stewart says, while the globe and Australia sit on a plateau of high temperature having risen to this point since the “end” of the LIA 160 years ago, any random upwards change in temperature will result in a scenario of “the Highest temperature since whenever”. This has NOTHING whatsoever to do with global warming, anthropogenioc, natural or otherwise. It is simply a factor of “being at the top”. Any fall in temperature will not ne noticed or noted, since a small radom change downwards is not going to take us back to the conditions of the LIA which would be required for the comment “the lowest temperature in 150 years!”

    So no. “Record temperatures are of no interst, not even symbolic interest – unless you are preparing for an international gathering in Paris in 2016!!!
    John Nicol

    • reichforthesky Says:

      As John states above, a paticular maximum temperature record being broken is not by itself that significant. As a result of the plateau (I.e. the last decade has been the warmest on record) then we would expect temperatures to be broken due to natural variation.

      What is more significant is the frequency of breaking records. This rate is indicative of the existence, or non-existence, of a warming trend. It would be useful for Ken, with the data he has at hand, to determine whether the number of record temperatures has increased recently.

      An interesting comparison would be to take the maximum temperature for each day of the year and determine in which year corresponds to the record maximum up till now. This would give you a relatively large data set of 366 days and for a hundred years of data 36,525 points. If there has been no change in temperatures then the years of record maxima woud be approximately equally distributed over the one hundred years. However if there has been a warming trend, then the number of record temperatures would be larger for the most recent years compared to the earlier years.

      I have done this exercise myself for a limited number of Australian locations. For the majority of locations the number of record maxima over recent years are significantly greater than for earlier years, especially for the last decade or two. Likewise doing the same exercise for record minima gives you a decrease in the number of minima for recent years compared with the earlier years.

      This is all consistent with a warming trend that is causing maximum temperature records to be broken. if Ken has analysis to the contrary, I would be fascinated to see it.

      • kenskingdom Says:

        No one is arguing there has been no warming trend. Of course there will be more max records broken on the way up and at the top even if it plateaus.

        • reichforthesky Says:

          Ken. I am glad you are in agreement regarding the warming trend. I know you can’t be responsible from commentary on other sites that link to your blog, but a large number on these sites dispute even this fact.

          I note that most of your blog entries dispute the BOM’s estimate of magnitude of the warming as the Acorn figures are around 0.9 degree per century or so while the raw data gives about 0.7 degrees per century. Because of this many people question the BOM’s adjustment they prefer instead to use the UAH satellite data compiled under the auspices of Spencer and Christy. You have on many occasions used this data yourself (e.g.

          Interestingly the UAH data shows a warming trend of 1.7 degree per century for Australia from 1979 until the present. The BOM Acorn data for the same period show an increase of about 1.2 degrees per century.

          It seems that the BOM may have significantly underestimated the rate of warming since 1979 and for this reason I strongly support Jennifer Marohasy’s call for an inquiry.

          Talk about an inconvenient truth (at least for this blog). Sorry for political reference, but when a blogger reports data that supports his contention and excludes any contrary data, then this is politics masquerading as science.

          By the way, as you may or may not have realized, I commented above using the name Mike R

          • kenskingdom Says:

            Mike, you do a great job defending the BOM but their actions wrt adjustments in Acorn are dubious to say the least. I have been analysing, checking data, and refuting the misinformation for years. Unfortunately they are getting more desparate lately and coming out with some real clangers. The Clayton’s Enquiry I very much doubt will be anything more than a whitewash. Your side may be on top at the moment but in the end I am confident the truth will out. In the meantime I will be guided by the data alone.

          • reichforthesky Says:

            Thank-you for your kind comment regarding my defence of the BOM but I have to ask , are you being guided by all of the data or just some selection of the data?

            Sorry for the harsh words but your attempt , via another generic attack on the credibility of the BOM , is clearly a diversionary tactic so that you can avoid addressing the issues regarding the UAH satellite data.

            The attempt has been successful and I have fallen for the bait. I have comments as follows.

            I haven’t the time or the inclination to investigate every data point in the BOM’s temperature records so I cannot challenge your criticism of some of the BOM’s data. All I can gather from your analysis is that the BOM have massaged (or manipulated if you prefer) the data which then gives a value for the temperature trend that is approximately 30% higher than for the raw data.

            I have, like you, been mystified how the ACORN temperatures are derived, in particular, why the Acorn data provides a higher value than the raw data suggesting that there is a systematic difference rather than a zero bias (if it was just random error corrections and adjustments).

            I think I now have some limited understanding as to why this occurs. It is probably due to the movement of weather stations from their original locations near the centre of towns to more remote nearby locations. Presumably this was done to avoid disturbance, early in the piece, from the proximity of the population , presence of traffic , etc. ,and later on, when urban heat island effects were recognized .

            This will have introduced a systematic bias towards lower temperatures (again primarily due to urban heat island effects) and the data analysis algorithms of the BOM have, as a result, compensated by adjusting the data upwards in these scenarios. The bureau’s (silly people as they are) intention was to try to compare apples with apples rather than comparison between two differing fruits (or even acorns).

            By the way the discrepancy between NASA/NOAA temperatures (which have been attacked in a similar fashion as the BOM data ) and UAH data global data is significantly smaller than for the Australian temperature data. The NOAA data shows an increase of 1.48 degrees per century while the UAH data shows a relatively smaller value of 1.40 degrees per century (6% difference). Not too much to get excited about.

            Look the data is out there, it just requires one to look in all directions rather than having a blinkered view that suits one agenda.

            So returning again to the issue at hand, I would appreciate your comments regarding the UAH temperature trends for Australia being much greater than either the raw or ACORN data. Is the problem the satellite data or the BOM data sets? Hopefully this question can provide food for thought and hopefully you can digest it.

  9. kenskingdom Says:

    Have a happy Easter, Mike R. Your rather obvious attempt to hijack the thread of this year old post has failed. You are welcome to comment but keep on topic. Or maybe you could start your own blog. I have better things to do.

    • reichforthesky Says:

      Ken have a happy Easter too. Many thanks for tolerating up to a point,a bit of dissent which is unfortunately rare when it comes to this topic. I will try to be ‘on topic’ in the future. What was the topic again? Oh the Marohasy letter regarding the BOM ACORN data. Clearly what I was discussing above had no relevance to this. I
      must humbly apologize.

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