Analysis of the BOM Annual Report.

The Bureau of Meteorology 2011 Annual Report. (LINK)
Guest post by Anthony Cox
What is going on with science information in this nation? It is this information from the BOM and CSIRO which provides justification for the introduction of the various anti global warming policies. So how reliable is this information from our two premier scientific research institutions?
In its 2011 report the BOM says:
“Australia was the only continent to record cooling and the nation’s 10-year average trend was still up”
This is a statement which is misleading in what it doesn’t say. For instance, the 10 year average temperature trend, based on the BOM’s own data, from January 2002 to December 2011, is this:
Clearly, the trend is down over this period regardless of whether this 10 year period is warmer than the preceding 10 year period.
In respect of Australia being the only continent to experience cooling over 2011, how then to explain this:
Image: Global Average Temperature [GAT] from land and satellites.

As can be seen the trend in the Global Average Temperature [GAT] is clearly down and that in 2011 GAT fell markedly. This down trend is clear in both the land based temperature [green] and the satellite temperature [purple]. How can Australia have been the only continent to cool in 2011 when GAT shows the whole world cooled?
The BOM is also reported as saying:
“Ocean temperatures – the warmest on record over the past two years – had actually assisted Australia’s heavy rainfall and cooler temperatures”
The clear implication from this is that the ocean is warming; it is not:
As can be seen there was a spike in the world’s sea surface temperature in 2009-2011, which is consistent with the BOM statement, but what is also plain is that the overall trend in sea surface temperature, over the last 10 years is down, further contradicting global warming.
It would appear that the only damage that global warming is causing is to the reputations of Australia’s scientific institutions.


  1. These two comments are in the 2011 report.
    “The Australian area-averaged mean temperature in 2011 was 0.14 °C below the 1961 to 1990 average of 21.81 °C.”

    “In 2011, maximum temperatures averaged 0.25 °C below normal across the country, while minima averaged 0.03 °C below normal.”
    I have been following the Australia mean temps closely this year since we had our coldest autumn ‘on record’. When I checked the mean minimums by compiling the monthly means from the BOM summaries, I come up with -0.13C, not -0.03C. This makes the mean temp -0.19C rather than the -0.14C quoted.
 Maybe someone can check these as I am no mathematician. I have just added the monthly averages and divided by 12.

    Min Max

    Jan 1.07 0.54

    Feb 0.53 -1.36

    Mar 0.02 -2.19

    Apr -0.96 -0.67

    May -1.75 -1.33

    Jun -1.16 -0.27

    Jul 0.41 0.6

    Aug 0.14 1.75

    Sep -0.57 0.92

    Oct 0.59 0.09

    Nov 0.32 -0.08

    Dec -0.28 -0.86

  2. There may be a difference between the calculation of the annual mean and the monthly mean adjusted to an annual figure; but some further analysis of your observations will be done and an answer posted.

  3. That would be great. I calculated the mean max temp using the same method and there was only a small discrepancy of about 0.02C. The BOM may have also posted a wrong figure in the monthly data summaries.

  4. Ian Hill has checked Anonymous's calculations and notes this:

    "I've verified those calculations and get a mean annual temperature, as calculated from the monthly data, of -0.19C for 2011. Checking all the other years 2002-2010, they are also all lower than the BoM's "direct" calculation of the annual mean by an average 0.065C. It's clear that the BoM calculates its mean annual temperature (whether it be max, min or mean) for Australia, States or individual sites, differently (ie independently) from its mean monthly temperature and (appears to) make no effort to ensure that an annual figure obtained from the monthly means agrees with the independently calculated annual mean. Note that the BoM has an annual mean time series from 1910 but monthly means from only 1950."

  5. Thanks Anthony and Ian.
    I just found it interesting that when I used the same method to calculate the yearly max mean it was -0.24C, almost the same as the figure quoted but min mean differed quite a bit. Maybe, as you point out re using different start dates, the long-term maximum mean temps have not varied from the 1950-2011 averages as much as the minimum temps.

  6. going from the data supplied by Anonymous Jan 6, 2012 11:16 AM I used the values, multiplied them by the days of the month, totaled the values and divided by 365 days for both values. For Min I ended with a value of -0.13715oC and for Max I ended with a value of -0.23145oC or a revised average of -0.184.


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