climate change wa

Pre 1931 CSIR, 1911-40 Year Book, RAW and ACORN temperature comparisons

Australia | NSW | Victoria | Queensland | South Australia | Tasmania | Western Australia | Northern Territory

Extreme minima and maxima | Temperature accuracy | Urban Heat Island | Discussion | Conclusion

All data Excel spreadsheets download (2.3mb)


Unadjusted temperatures published by the Weather Bureau in the mid 20th century indicate a warmer Australian climate before 1940 than calculated with RAW or ACORN adjustments and suggest warming from the 1800s to 2014 at approximately half the rate calculated by ACORN since 1910.


Pristine historic Weather Bureau temperatures from 226 weather stations before 1931 and from 44 stations between 1911 and 1940 can be compared against corresponding locations within Bureau of Meteorology RAW data and adjusted ACORN temperatures.


Among 226 locations listed by the CSIR, the mean temperature increased 0.5C from <1931 to 2000-2014, or 0.4586C to be precise.

Key points:

csir and bom raw comparison


state csir and acorn temperatures

In the table above, 53 of the 66 stations had a known year of Stevenson screen installation, averaging 1901, with 28.4% of temperatures recorded in non-Stevenson shelters before 1931 in the CSIR dataset


australia csir 1933 cover


australia year book 1953 cover

Year Book mean temperatures recorded in Stevenson screens by Australia's leading meteorologists at weather stations across the country from 1911 to 1940 were the same as the BoM RAW mean from their start years to 2014, with an increase of 0.4C by 2000-2014.

In the adjusted ACORN dataset used by government to measure climate change in Australia, comparable weather station mean temperatures from the years 2000 to 2014 were 0.5C warmer than unadjusted temperatures before 1931, as collated by the CSIR, with the main artificial influences being thermometer screens and UHI.

The BoM Annual Climate Statement 2014 shows Australia's 10 year mean average temperature from 2005 to 2014 averaged 0.55C above the 1961-90 average of 21.81C, based on an ACORN network of about 100 non-urban weather stations, and State of the Climate 2014 estimates Australia's area-averaged mean climate has warmed 0.91C since 1910.

Note: the 1954 Year Book includes 1911-40 average minima and maxima at a further 40 weather stations across Australia, creating a network of 84 locations that collectively show a 0.3C increase in Australian raw mean temperature from 1911-40 to 2000-14. The 84 station network analysis can be downloaded here (Excel 1.3mb).

Historic temperature sources:

Current temperature sources:

Fahrenheit recordings in the CSIR and Year Book documents are converted to Celsius and tabulated in spreadsheets to allow comparison of temperatures at corresponding locations in the Bureau of Meteorology's RAW and ACORN datasets within different timeframes.

Australia | NSW | Victoria | Queensland | South Australia | Tasmania | Western Australia | Northern Territory

Extreme minima and maxima | Temperature accuracy | Urban Heat Island | Discussion | Conclusion

All data Excel spreadsheets download (2.3mb)

Australia

44 stations in Year Book 1911-40 vs RAW average

  • The 44 Australian stations in the Year Book 1911-40 had a mean maximum of 23.9C compared to a long-term RAW average at those 44 stations of 24.0C sourced from BoM Climate Data Online
  • The 44 Australian stations in the Year Book 1911-40 had a mean minimum of 12.4C compared to a long-term RAW average at those 44 stations of 12.3C sourced from BoM Climate Data Online
  • The 44 Australian stations in the Year Book 1911-40 had a mean temperature of 18.1C compared to a long-term RAW average at those 44 stations of 18.1C sourced from BoM Climate Data Online

Same 44 stations in <1931 CSIR vs RAW average

  • The same 44 Australian stations in the <1931 CSIR pamphlet had a mean maximum of 23.9C compared to a long-term RAW average at those 44 stations of 24.0C sourced from BoM Climate Data Online
  • The same 44 Australian stations in the <1931 CSIR pamphlet had a mean minimum of 12.3C compared to a long-term RAW average at those 44 stations of 12.3C sourced from BoM Climate Data Online
  • The same 44 Australian stations in the <1931 CSIR pamphlet had a mean temperature of 18.1C compared to a long-term RAW average at those 44 stations of 18.1C sourced from BoM Climate Data Online

44 stations in Year Book 1911-40 vs 2000-2014 RAW average

  • The 44 Australian stations in the Year Book 1911-40 had a mean maximum of 23.9C compared to a 2000-2014 RAW average at those 44 stations of 24.4C sourced from BoM Climate Data Online
  • The 44 Australian stations in the Year Book 1911-40 had a mean minimum of 12.4C compared to a 2000-2014 RAW average at those 44 stations of 12.5C sourced from BoM Climate Data Online
  • The 44 Australian stations in the Year Book 1911-40 had a mean temperature of 18.1C compared to a 2000-2014 RAW average at those 44 stations of 18.5C sourced from BoM Climate Data Online

226 stations in <1931 CSIR vs RAW average

  • The 226 Australian stations in the <1931 CSIR pamphlet had a mean maximum of 24.3C compared to a long-term RAW average at those 226 stations of 24.4C sourced from BoM Climate Data Online
  • The 226 Australian stations in the <1931 CSIR pamphlet had a mean minimum of 11.7C compared to a long-term RAW average at those 226 stations of 12.0C sourced from BoM Climate Data Online
  • The 226 Australian stations in the <1931 CSIR pamphlet had a mean temperature of 18.0C compared to a long-term RAW average at those 226 stations of 18.2C sourced from BoM Climate Data Online

226 stations in <1931 CSIR vs RAW 2000-2014

  • The 226 Australian stations in the <1931 CSIR pamphlet had a mean maximum of 24.3C compared to a 2000-2014 RAW average at those 226 stations of 24.7C sourced from BoM Climate Data Online
  • The 226 Australian stations in the <1931 CSIR pamphlet had a mean minimum of 11.7C compared to a 2000-2014 RAW average at those 226 stations of 12.2C sourced from BoM Climate Data Online
  • The 226 Australian stations in the <1931 CSIR pamphlet had a mean temperature of 18.0C compared to a 2000-2014 RAW average at those 226 stations of 18.5C sourced from BoM Climate Data Online

66 stations in <1931 CSIR vs ACORN 1910-1931

  • The 66 Australian stations in the <1931 CSIR pamphlet that didn't relocate and eventually became part of the ACORN network had a mean maximum of 24.9C compared to a 1910-1931 average at those 66 stations of 24.6C sourced from the adjusted ACORN dataset
  • The 66 Australian stations in the <1931 CSIR pamphlet that didn't relocate and eventually became part of the ACORN network had a mean minimum of 13.0C compared to a 1910-1931 average at those 66 stations of 12.6C sourced from the adjusted ACORN dataset
  • The 66 Australian stations in the <1931 CSIR pamphlet that didn't relocate and eventually became part of the ACORN network had a mean temperature of 18.9C compared to a 1910-1931 average at those 66 stations of 18.6C sourced from the adjusted ACORN dataset

79 stations in <1931 CSIR vs ACORN 2000-2014

  • The 79 Australian locations in the <1931 CSIR pamphlet that eventually became part of the ACORN network had a mean maximum of 25.1C compared to a 2000-2014 average at those 79 stations of 25.6C sourced from the adjusted ACORN dataset
  • The 79 Australian locations in the <1931 CSIR pamphlet that eventually became part of the ACORN network had a mean minimum of 13.0C compared to a 2000-2014 average at those 79 stations of 13.6C sourced from the adjusted ACORN dataset
  • The 79 Australian locations in the <1931 CSIR pamphlet that eventually became part of the ACORN network had a mean temperature of 19.1C compared to a 2000-2014 average at those 79 stations of 19.6C sourced from the adjusted ACORN dataset

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New South Wales

11 stations in Year Book 1911-40 vs RAW average

  • The 11 NSW stations in the Year Book 1911-40 had a mean maximum of 22.2C compared to a long-term RAW average at those 11 stations of 22.2C sourced from BoM Climate Data Online
  • The 11 NSW stations in the Year Book 1911-40 had a mean minimum of 10.7C compared to a long-term RAW average at those 11 stations of 10.6C sourced from BoM Climate Data Online
  • The 11 NSW stations in the Year Book 1911-40 had a mean temperature of 16.5C compared to a long-term RAW average at those 11 stations of 16.4C sourced from BoM Climate Data Online

Same 11 stations in <1931 CSIR vs RAW average

  • The same 11 NSW stations in the <1931 CSIR pamphlet had a mean maximum of 22.5C compared to a long-term RAW average at those 11 stations of 22.2C sourced from BoM Climate Data Online
  • The same 11 NSW stations in the <1931 CSIR pamphlet had a mean minimum of 10.4C compared to a long-term RAW average at those 11 stations of 10.6C sourced from BoM Climate Data Online
  • The same 11 NSW stations in the <1931 CSIR pamphlet had a mean temperature of 16.5C compared to a long-term RAW average at those 11 stations of 16.4C sourced from BoM Climate Data Online

72 stations in <1931 CSIR vs RAW average

  • The 72 NSW stations in the <1931 CSIR pamphlet had a mean maximum of 23.3C compared to a long-term RAW average at those 72 stations of 23.1C sourced from BoM Climate Data Online
  • The 72 NSW stations in the <1931 CSIR pamphlet had a mean minimum of 9.8C compared to a long-term RAW average at those 72 stations of 10.0C sourced from BoM Climate Data Online
  • The 72 NSW stations in the <1931 CSIR pamphlet had a mean temperature of 16.5C compared to a long-term RAW average at those 72 stations of 16.5C sourced from BoM Climate Data Online

72 stations in <1931 CSIR vs 2000-2014 RAW average

  • The 72 NSW stations in the <1931 CSIR pamphlet had a mean maximum of 23.3C compared to a 2000-2014 RAW average at those 72 stations of 23.4C sourced from BoM Climate Data Online
  • The 72 NSW stations in the <1931 CSIR pamphlet had a mean minimum of 9.8C compared to a 2000-2014 RAW average at those 72 stations of 10.2C sourced from BoM Climate Data Online
  • The 72 NSW stations in the <1931 CSIR pamphlet had a mean temperature of 16.5C compared to a 2000-2014 RAW average at those 72 stations of 16.8C sourced from BoM Climate Data Online

17 ACORN stations in <1931 CSIR vs ACORN 1910-2014 and 2000-14

  • The 17 NSW ACORN stations in the <1931 CSIR pamphlet had a mean maximum of 24.0C compared to the 1910-2014 ACORN average at those stations of 23.6C and a 2000-14 ACORN average of 24.3C
  • The 17 NSW ACORN stations in the <1931 CSIR pamphlet had a mean minimum of 10.7C compared to the 1910-2014 ACORN average at those stations of 10.5C and a 2000-14 ACORN average of 11.1C
  • The 17 NSW ACORN stations in the <1931 CSIR pamphlet had a mean temperature of 17.4C compared to the 1910-2014 ACORN average at those stations of 17.1C and a 2000-14 ACORN average of 17.7C

12 ACORN stations in <1931 CSIR vs ACORN 1910-31, 1910-2014 and 2000-14

  • The 12 NSW ACORN stations that opened before 1931 in the CSIR pamphlet had a mean maximum of 24.1C compared to the 1910-1931 ACORN average of 23.7C, the 1910-2014 ACORN average of 23.8C and the 2000-14 ACORN average of 24.5C
  • The 12 NSW ACORN stations that opened before 1931 in the CSIR pamphlet had a mean minimum of 11.0C compared to the 1910-1931 ACORN average of 10.2C, the 1910-2014 ACORN average of 10.6C and the 2000-14 ACORN average of 11.3C
  • The 12 NSW ACORN stations that opened before 1931 in the CSIR pamphlet had a mean temperature of 17.5C compared to the 1910-1931 ACORN average of 16.9C, the 1910-2014 ACORN average of 17.2C and the 2000-14 ACORN average of 17.9C

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Victoria

Seven stations in Year Book 1911-40 vs RAW average

  • The seven Victoria stations in the Year Book 1911-40 had a mean maximum of 20.7C compared to a long-term RAW average at those seven stations of 21.0C sourced from BoM Climate Data Online
  • The seven Victoria stations in the Year Book 1911-40 had a mean minimum of 8.9C compared to a long-term RAW average at those seven stations of 8.5C sourced from BoM Climate Data Online
  • The seven Victoria stations in the Year Book 1911-40 had a mean temperature of 14.8C compared to a long-term RAW average at those seven stations of 14.7C sourced from BoM Climate Data Online

Same seven stations in <1931 CSIR vs RAW average

  • The same seven Victoria stations in the <1931 CSIR pamphlet had a mean maximum of 20.9C compared to a long-term RAW average at those seven stations of 21.0C sourced from BoM Climate Data Online
  • The same seven Victoria stations in the <1931 CSIR pamphlet had a mean minimum of 8.8C compared to a long-term RAW average at those seven stations of 8.5C sourced from BoM Climate Data Online
  • The same seven Victoria stations in the <1931 CSIR pamphlet had a mean temperature of 14.9C compared to a long-term RAW average at those seven stations of 14.7C sourced from BoM Climate Data Online

34 stations in <1931 CSIR vs RAW average

  • The 34 Victoria stations in the <1931 CSIR pamphlet had a mean maximum of 19.9C compared to a long-term RAW average at those 33 stations of 20.0C sourced from BoM Climate Data Online
  • The 34 Victoria stations in the <1931 CSIR pamphlet had a mean minimum of 8.6C compared to a long-term RAW average at those 33 stations of 8.6C sourced from BoM Climate Data Online
  • The 34 Victoria stations in the <1931 CSIR pamphlet had a mean temperature of 14.3C compared to a long-term RAW average at those 33 stations of 14.3C sourced from BoM Climate Data Online

34 stations in <1931 CSIR vs 2000-2014 RAW average

  • The 34 Victoria stations in the <1931 CSIR pamphlet had a mean maximum of 19.9C compared to a 2000-2014 RAW average at those 34 stations of 20.4C sourced from BoM Climate Data Online
  • The 34 Victoria stations in the <1931 CSIR pamphlet had a mean minimum of 8.6C compared to a 2000-2014 RAW average at those 34 stations of 8.8C sourced from BoM Climate Data Online
  • The 34 Victoria stations in the <1931 CSIR pamphlet had a mean temperature of 14.3C compared to a 2000-2014 RAW average at those 34 stations of 14.6C sourced from BoM Climate Data Online

Nine ACORN stations in <1931 CSIR vs ACORN 1910-2014 and 2000-14

  • The nine Victoria ACORN stations in the <1931 CSIR pamphlet had a mean maximum of 20.5C compared to the 1910-2014 ACORN average at those stations of 20.0C and a 2000-14 ACORN average of 20.8C
  • The nine Victoria ACORN stations in the <1931 CSIR pamphlet had a mean minimum of 9.7C compared to the 1910-2014 ACORN average at those stations of 9.7C and a 2000-14 ACORN average of 10.3C
  • The nine Victoria ACORN stations in the <1931 CSIR pamphlet had a mean temperature of 15.1C compared to the 1910-2014 ACORN average at those stations of 14.9C and a 2000-14 ACORN average of 15.5C

Eight ACORN stations in <1931 CSIR vs ACORN 1910-31, 1910-2014 and 2000-14

  • The eight Victoria ACORN stations that opened before 1931 in the CSIR pamphlet had a mean maximum of 20.5C compared to the 1910-1931 ACORN average at those stations of 19.9C, the 1910-2014 ACORN average of 20.1C and the 2000-14 ACORN average of 20.9C
  • The eight Victoria ACORN stations that opened before 1931 in the CSIR pamphlet had a mean minimum of 9.9C compared to the 1910-1931 ACORN average at those stations of 9.7C, the 1910-2014 ACORN average of 10.0C and the 2000-14 ACORN average of 10.5C
  • The eight Victoria ACORN stations that opened before 1931 in the CSIR pamphlet had a mean temperature of 15.2C compared to the 1910-1931 ACORN average at those stations of 14.8C, the 1910-2014 ACORN average of 15.0C and the 2000-14 ACORN average of 15.7C

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Queensland

Nine stations in Year Book 1911-40 vs RAW average

  • The nine Queensland stations in the Year Book 1911-40 had a mean maximum of 28.2C compared to a long-term RAW average at those nine stations of 28.2C sourced from BoM Climate Data Online
  • The nine Queensland stations in the Year Book 1911-40 had a mean minimum of 16.7C compared to a long-term RAW average at those nine stations of 17.0C sourced from BoM Climate Data Online
  • The nine Queensland stations in the Year Book 1911-40 had a mean temperature of 22.5C compared to a long-term RAW average at those nine stations of 22.6C sourced from BoM Climate Data Online

Same nine stations in <1931 CSIR vs RAW average

  • The same nine Queensland stations in the <1931 CSIR pamphlet had a mean maximum of 28.1C compared to a long-term RAW average at those nine stations of 28.2C sourced from BoM Climate Data Online
  • The same nine Queensland stations in the <1931 CSIR pamphlet had a mean minimum of 16.5C compared to a long-term RAW average at those nine stations of 17.0C sourced from BoM Climate Data Online
  • The same nine Queensland stations in the <1931 CSIR pamphlet had a mean temperature of 22.3C compared to a long-term RAW average at those nine stations of 22.6C sourced from BoM Climate Data Online

54 stations in <1931 CSIR vs RAW average

  • The 54 Queensland stations in the <1931 CSIR pamphlet had a mean maximum of 28.8C compared to a long-term RAW average at those 54 stations of 29.0C sourced from BoM Climate Data Online
  • The 54 Queensland stations in the <1931 CSIR pamphlet had a mean minimum of 15.7C compared to a long-term RAW average at those 54 stations of 15.7C sourced from BoM Climate Data Online
  • The 54 Queensland stations in the <1931 CSIR pamphlet had a mean temperature of 22.3C compared to a long-term RAW average at those 54 stations of 22.3C sourced from BoM Climate Data Online

54 stations in <1931 CSIR vs 2000-2014 RAW average

  • The 54 Queensland stations in the <1931 CSIR pamphlet had a mean maximum of 28.8C compared to a 2000-2014 RAW average at those 54 stations of 29.3C sourced from BoM Climate Data Online
  • The 54 Queensland stations in the <1931 CSIR pamphlet had a mean minimum of 15.7C compared to a 2000-2014 RAW average at those 54 stations of 16.5C sourced from BoM Climate Data Online
  • The 54 Queensland stations in the <1931 CSIR pamphlet had a mean temperature of 22.3C compared to a 2000-2014 RAW average at those 54 stations of 22.9C sourced from BoM Climate Data Online

23 ACORN stations in <1931 CSIR vs ACORN 1910-2014 and 2000-14

  • The 23 Queensland ACORN stations in the <1931 CSIR pamphlet had a mean maximum of 29.3C compared to the 1910-2014 ACORN average at those stations of 29.3C and a 2000-14 ACORN average of 29.7C
  • The 23 Queensland ACORN stations in the <1931 CSIR pamphlet had a mean minimum of 16.5C compared to the 1910-2014 ACORN average at those stations of 16.6C and a 2000-14 ACORN average of 17.2C
  • The 23 Queensland ACORN stations in the <1931 CSIR pamphlet had a mean temperature of 22.9C compared to the 1910-2014 ACORN average at those stations of 23.0C and a 2000-14 ACORN average of 23.5C

16 ACORN stations in <1931 CSIR vs ACORN 1910-31, 1910-2014 and 2000-14

  • The 16 Queensland ACORN stations that opened before 1931 in the CSIR pamphlet had a mean maximum of 29.6C compared to the 1910-1931 ACORN average at those stations of 29.3C, the 1910-2014 ACORN average of 29.5C and the 2000-14 ACORN average of 30.0C
  • The 16 Queensland ACORN stations that opened before 1931 in the CSIR pamphlet had a mean minimum of 16.6C compared to the 1910-1931 ACORN average at those stations of 16.4C, the 1910-2014 ACORN average of 16.9C and the 2000-14 ACORN average of 17.5C
  • The 16 Queensland ACORN stations that opened before 1931 in the CSIR pamphlet had a mean temperature of 23.1C compared to the 1910-1931 ACORN average at those stations of 22.9C, the 1910-2014 ACORN average of 23.2C and the 2000-14 ACORN average of 23.7C

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South Australia

Five stations in Year Book 1911-40 vs RAW average

  • The five South Australia stations in the Year Book 1911-40 had a mean maximum of 22.2C compared to a long-term RAW average at those five stations of 22.2C sourced from BoM Climate Data Online
  • The five South Australia stations in the Year Book 1911-40 had a mean minimum of 10.6C compared to a long-term RAW average at those five stations of 10.3C sourced from BoM Climate Data Online
  • The five South Australia stations in the Year Book 1911-40 had a mean temperature of 16.4C compared to a long-term RAW average at those five stations of 16.3C sourced from BoM Climate Data Online

Same five stations in <1931 CSIR vs RAW average

  • The same five South Australia stations in the <1931 CSIR pamphlet had a mean maximum of 22.2C compared to a long-term RAW average at those five stations of 22.2C sourced from BoM Climate Data Online
  • The same five South Australia stations in the <1931 CSIR pamphlet had a mean minimum of 10.5C compared to a long-term RAW average at those five stations of 10.3C sourced from BoM Climate Data Online
  • The same five South Australia stations in the <1931 CSIR pamphlet had a mean temperature of 16.3C compared to a long-term RAW average at those five stations of 16.3C sourced from BoM Climate Data Online

18 stations in <1931 CSIR vs 2000-2014 RAW average

  • The 18 South Australia stations in the <1931 CSIR pamphlet had a mean maximum of 21.8C compared to a 2000-2014 RAW average at those 18 stations of 22.7C sourced from BoM Climate Data Online
  • The 18 South Australia stations in the <1931 CSIR pamphlet had a mean minimum of 10.4C compared to a 2000-2014 RAW average at those 18 stations of 10.6C sourced from BoM Climate Data Online
  • The 18 South Australia stations in the <1931 CSIR pamphlet had a mean temperature of 16.1C compared to a 2000-2014 RAW average at those 18 stations of 16.6C sourced from BoM Climate Data Online

18 stations in <1931 CSIR vs RAW average

  • The 18 South Australia stations in the <1931 CSIR pamphlet had a mean maximum of 21.8C compared to a long-term RAW average at those 18 stations of 22.3C sourced from BoM Climate Data Online
  • The 18 South Australia stations in the <1931 CSIR pamphlet had a mean minimum of 10.4C compared to a long-term RAW average at those 18 stations of 10.3C sourced from BoM Climate Data Online
  • The 18 South Australia stations in the <1931 CSIR pamphlet had a mean temperature of 16.1C compared to a long-term RAW average at those 18 stations of 16.3C sourced from BoM Climate Data Online

Seven ACORN stations in <1931 CSIR vs ACORN 1910-31, 1910-2014 and 2000-14

  • The seven South Australia ACORN stations that opened before 1931 in the CSIR pamphlet had a mean maximum of 21.9C compared to the 1910-1931 ACORN average at those stations of 22.0C, the 1910-2014 ACORN average of 21.9C and the 2000-14 ACORN average of 22.6C
  • The seven South Australia ACORN stations that opened before 1931 in the CSIR pamphlet had a mean minimum of 10.6C compared to the 1910-1931 ACORN average at those stations of 10.4C, the 1910-2014 ACORN average of 10.6C and the 2000-14 ACORN average of 11.1C
  • The seven South Australia ACORN stations that opened before 1931 in the CSIR pamphlet had a mean temperature of 16.3C compared to the 1910-1931 ACORN average at those stations of 16.2C, the 1910-2014 ACORN average of 16.2C and the 2000-14 ACORN average of 16.9C

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Tasmania

Three stations in Year Book 1911-40 vs RAW average

  • The three Tasmania stations in the Year Book 1911-40 had a mean maximum of 16.8C compared to a long-term RAW average at those three stations of 17.3C sourced from BoM Climate Data Online
  • The three Tasmania stations in the Year Book 1911-40 had a mean minimum of 7.7C compared to a long-term RAW average at those three stations of 8.0C sourced from BoM Climate Data Online
  • The three Tasmania stations in the Year Book 1911-40 had a mean temperature of 12.3C compared to a long-term RAW average at those three stations of 12.7C sourced from BoM Climate Data Online

Same three stations in <1931 CSIR vs RAW average

  • The same three Tasmania stations in the <1931 CSIR pamphlet had a mean maximum of 16.9C compared to a long-term RAW average at those three stations of 17.3C sourced from BoM Climate Data Online
  • The same three Tasmania stations in the <1931 CSIR pamphlet had a mean minimum of 8.1C compared to a long-term RAW average at those three stations of 8.0C sourced from BoM Climate Data Online
  • The same three Tasmania stations in the <1931 CSIR pamphlet had a mean temperature of 12.5C compared to a long-term RAW average at those three stations of 12.7C sourced from BoM Climate Data Online

Eight stations in <1931 CSIR vs 2000-2014 RAW average

  • The eight Tasmania stations in the <1931 CSIR pamphlet had a mean maximum of 16.7C compared to a 2000-2014 RAW average at those eight stations of 17.5C sourced from BoM Climate Data Online
  • The eight Tasmania stations in the <1931 CSIR pamphlet had a mean minimum of 8.4C compared to a 2000-2014 RAW average at those eight stations of 9.2C sourced from BoM Climate Data Online
  • The eight Tasmania stations in the <1931 CSIR pamphlet had a mean temperature of 12.5C compared to a 2000-2014 RAW average at those eight stations of 13.3C sourced from BoM Climate Data Online

Eight stations in <1931 CSIR vs RAW average

  • The eight Tasmania stations in the <1931 CSIR pamphlet had a mean maximum of 16.7C compared to a long-term RAW average at those eight stations of 17.1C sourced from BoM Climate Data Online
  • The eight Tasmania stations in the <1931 CSIR pamphlet had a mean minimum of 8.4C compared to a long-term RAW average at those eight stations of 8.9C sourced from BoM Climate Data Online
  • The eight Tasmania stations in the <1931 CSIR pamphlet had a mean temperature of 12.5C compared to a long-term RAW average at those eight stations of 13.0C sourced from BoM Climate Data Online

Five ACORN stations in <1931 CSIR vs ACORN 1910-31, 1910-2014 and 2000-14

  • The five Tasmania ACORN stations that opened before 1931 in the CSIR pamphlet had a mean maximum of 16.4C compared to the 1910-1931 ACORN average at those stations of 16.5C, the 1910-2014 ACORN average of 16.7C and the 2000-14 ACORN average of 17.3C
  • The five Tasmania ACORN stations that opened before 1931 in the CSIR pamphlet had a mean minimum of 8.5C compared to the 1910-1931 ACORN average at those stations of 8.4C, the 1910-2014 ACORN average of 8.6C and the 2000-14 ACORN average of 9.2C
  • The five Tasmania ACORN stations that opened before 1931 in the CSIR pamphlet had a mean temperature of 12.5C compared to the 1910-1931 ACORN average at those stations of 12.4C, the 1910-2014 ACORN average of 12.7C and the 2000-14 ACORN average of 13.2C

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Western Australia

Six stations in Year Book 1911-40 vs RAW average

  • The six WA stations in the Year Book 1911-40 had a mean maximum of 25.0C compared to a long-term RAW average at those six stations of 25.8C sourced from BoM Climate Data Online
  • The six WA stations in the Year Book 1911-40 had a mean minimum of 14.0C compared to a long-term RAW average at those six stations of 13.4C sourced from BoM Climate Data Online
  • The six WA stations in the Year Book 1911-40 had a mean temperature of 19.5C compared to a long-term RAW average at those six stations of 19.6C sourced from BoM Climate Data Online

Same six stations in <1931 CSIR vs RAW average

  • The same six WA stations in the <1931 CSIR pamphlet had a mean maximum of 24.9C compared to a long-term RAW average at those six stations of 25.8C sourced from BoM Climate Data Online
  • The same six WA stations in the <1931 CSIR pamphlet had a mean minimum of 13.9C compared to a long-term RAW average at those six stations of 13.4C sourced from BoM Climate Data Online
  • The same six WA stations in the <1931 CSIR pamphlet had a mean temperature of 19.4C compared to a long-term RAW average at those six stations of 19.6C sourced from BoM Climate Data Online

36 stations in <1931 CSIR vs 2000-2014 RAW average

  • The 36 Western Australia stations in the <1931 CSIR pamphlet had a mean maximum of 25.5C compared to a 2000-2014 RAW average at those 36 stations of 26.4C sourced from BoM Climate Data Online
  • The 36 Western Australia stations in the <1931 CSIR pamphlet had a mean minimum of 13.2C compared to a 2000-2014 RAW average at those 36 stations of 13.6C sourced from BoM Climate Data Online
  • The 36 Western Australia stations in the <1931 CSIR pamphlet had a mean temperature of 19.3C compared to a 2000-2014 RAW average at those 36 stations of 20.0C sourced from BoM Climate Data Online

36 stations in <1931 CSIR vs RAW average

  • The 36 WA stations in the <1931 CSIR pamphlet had a mean maximum of 25.5C compared to a long-term RAW average at those 36 stations of 26.1C sourced from BoM Climate Data Online
  • The 36 WA stations in the <1931 CSIR pamphlet had a mean minimum of 13.2C compared to a long-term RAW average at those 36 stations of 13.5C sourced from BoM Climate Data Online
  • The 36 WA stations in the <1931 CSIR pamphlet had a mean temperature of 19.3C compared to a long-term RAW average at those 36 stations of 19.8C sourced from BoM Climate Data Online

15 ACORN stations in <1931 CSIR vs ACORN 1910-31, 1910-2014 and 2000-14

  • The 15 WA ACORN stations that opened before 1931 in the CSIR pamphlet had a mean maximum of 25.6C compared to the 1910-1931 ACORN average at those stations of 25.7C, the 1910-2014 ACORN average of 26.0C and the 2000-14 ACORN average of 26.5C
  • The 15 WA ACORN stations that opened before 1931 in the CSIR pamphlet had a mean minimum of 13.8C compared to the 1910-1931 ACORN average at those stations of 13.4C, the 1910-2014 ACORN average of 13.7C and the 2000-14 ACORN average of 14.2C
  • The 15 WA ACORN stations that opened before 1931 in the CSIR pamphlet had a mean temperature of 19.7C compared to the 1910-1931 ACORN average at those stations of 19.5C, the 1910-2014 ACORN average of 19.9C and the 2000-14 ACORN average of 20.3C

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Northern Territory

Three stations in Year Book 1911-40 vs RAW average

  • The three Northern Territory stations in the Year Book 1911-40 had a mean maximum of 31.7C compared to a long-term RAW average at those three stations of 31.5C sourced from BoM Climate Data Online
  • The three Northern Territory stations in the Year Book 1911-40 had a mean minimum of 18.6C compared to a long-term RAW average at those three stations of 18.5C sourced from BoM Climate Data Online
  • The three Northern Territory stations in the Year Book 1911-40 had a mean temperature of 25.1C compared to a long-term RAW average at those three stations of 25.0C sourced from BoM Climate Data Online

Same three stations in <1931 CSIR vs RAW average

  • The same three Northern Territory stations in the <1931 CSIR pamphlet had a mean maximum of 32.0C compared to a long-term RAW average at those three stations of 31.5C sourced from BoM Climate Data Online
  • The same three Northern Territory stations in the <1931 CSIR pamphlet had a mean minimum of 18.6C compared to a long-term RAW average at those three stations of 18.5C sourced from BoM Climate Data Online
  • The same three Northern Territory stations in the <1931 CSIR pamphlet had a mean temperature of 25.3C compared to a long-term RAW average at those three stations of 25.0C sourced from BoM Climate Data Online

Four stations in <1931 CSIR vs 2000-2014 RAW average

  • The four Northern Territory stations in the <1931 CSIR pamphlet had a mean maximum of 31.9C compared to a 2000-2014 RAW average at those four stations of 32.0C sourced from BoM Climate Data Online
  • The four Northern Territory stations in the <1931 CSIR pamphlet had a mean minimum of 18.6C compared to a 2000-2014 RAW average at those four stations of 18.7C sourced from BoM Climate Data Online
  • The four Northern Territory stations in the <1931 CSIR pamphlet had a mean temperature of 25.3C compared to a 2000-2014 RAW average at those four stations of 25.3C sourced from BoM Climate Data Online

Four stations in <1931 CSIR vs RAW average

  • The four Northern Territory stations in the <1931 CSIR pamphlet had a mean maximum of 31.9C compared to a long-term RAW average at those four stations of 31.6C sourced from BoM Climate Data Online
  • The four Northern Territory stations in the <1931 CSIR pamphlet had a mean minimum of 18.6C compared to a long-term RAW average at those four stations of 18.9C sourced from BoM Climate Data Online
  • The four Northern Territory stations in the <1931 CSIR pamphlet had a mean temperature of 25.3C compared to a long-term RAW average at those four stations of 25.3C sourced from BoM Climate Data Online

Three ACORN stations in <1931 CSIR vs ACORN 1910-31, 1910-2014 and 2000-14

  • The three Northern Territory ACORN stations that opened before 1931 in the CSIR pamphlet had a mean maximum of 31.1C compared to the 1910-1931 ACORN average at those stations of 30.2C, the 1910-2014 ACORN average of 30.7C and the 2000-14 ACORN average of 31.2C
  • The three Northern Territory ACORN stations that opened before 1931 in the CSIR pamphlet had a mean minimum of 18.3C compared to the 1910-1931 ACORN average at those stations of 18.0C, the 1910-2014 ACORN average of 18.4C and the 2000-14 ACORN average of 18.8C
  • The three Northern Territory ACORN stations that opened before 1931 in the CSIR pamphlet had a mean temperature of 24.7C compared to the 1910-1931 ACORN average at those stations of 24.1C, the 1910-2014 ACORN average of 24.5C and the 2000-14 ACORN average of 25.0C

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All data Excel spreadsheets download (2.3mb)

Extreme temperatures

  • Comparing extreme temperatures at the 44 locations in the Year Book 1911-40 with daily extremes listed July 2014 in BoM Climate Data Online at those same locations, the average hottest-ever daily temperatures have collectively been 35.8C in the Year Book 1911-40 compared to 36.1C in CDO RAW, and the coldest daily temperatures have collectively averaged 3.1C in the Year Book 1911-40 compared to 2.4C in CDO RAW.


Temperature accuracy

All temperatures in the Year Book 1911-40, RAW and ACORN datasets were recorded in Stevenson screens.

The average start year for the 226 CSIR locations was 1901 and approximately two thirds of recordings to 1931 were from thermometers in Stevenson screens. Click here for pop-up CSIR weather station start years.

The approximate third of recordings from Greenwich/Glaisher screens or open shade thermometers tended to record warmer maxima and cooler minima in different seasons.

Adelaide's West Terrace weather station used a combination of Greenwich/Glaisher and Stevenson screens from 1887. Nichols et al in Historical Thermometer Exposures in Australia summarised the Adelaide experiment results:

"The minima measured in the two exposures are similar throughout the year, with Stevenson screen minima being about 0.2C warmer. The maxima measured in the Stevenson screen are cooler than those in the Glaisher stand and the difference varies seasonally. The difference is only about 0.2C in winter, but reaches nearly 1C in summer."

In Exposure, instrumentation, and observing practice effects on land temperature measurements, ACORN architect Blair Trewin from the BoM states:

"In particular, a number of studies found that the Glaisher stand, in widespread use in English speaking countries prior to Stevenson screen introduction, had a warm bias in maximum temperatures, ranging from 0.2C to 0.6C in annual means and reaching up to 1.0C in mean summer maximum temperatures and 2–3C on some individual hot days. Minimum temperatures tended to have a cool bias of 0.2–0.3C all year. These results were based on, among others, a 60-year set of parallel observations at Adelaide, Australia. A warm bias in maximum temperatures, particularly on sunny days and/or in summer, was also common to numerous other pre-Stevenson exposures."

In Effects of Changing Exposure of Thermometers at Land Stations, D.E Parker from the Hadley Centre Meteorological Office in the UK states:

"The average difference for the four investigations quoted here was, however, only 0.01C, with the Glaisher value colder. The indications are thus for an insignificant annual mean difference between the exposures, but for a significant raising of daytime and summer-mean temperatures, and a significant lowering of night-time and possibly winter-mean temperatures, in the Glaisher stand relative to the Stevenson screen."

Comparisons show the monthly Glaisher screen influences on Stevenson maximum recordings in Adelaide were:

Dec -1.1C, Jan -1.0C, Feb -1.0C
Mar -0.9C, Apr -0.5C, May -0.1C
Jun 0C, Jul 0C, Aug -0.2C
Sep -0.5C, Oct -0.8C, Nov -0.9C

Trewin reported that the Glaisher upward maxima bias averaged 0.4C and downward minima bias averaged -0.25C over a year, resulting in an average upward mean temperature bias of 0.075C which if applied to approximately one third of all temperatures in the CSIR dataset has no influence on total averages to 1931. This is supported by the Parker finding of a 0.01C difference between the Glaisher and Stevenson screens, with Glaisher cooler.

In Manual of Meteorology published in 1932, a comparison is made of Stevenson and Glaisher screens at Kew University from 1881 to 1915, with the Stevenson mean temperature recording an average 0.2C warmer:


glaisher and stevenson comparison

In the <1931 CSIR dataset comparisons above, the average start years and number of stations open before or since the year 1900 should be considered when estimating any likely Glaisher or other screen influence:

Australia - 1901 (69 open before 1900, 157 since)
NSW - 1901 (21 open before 1900, 51 since)
Victoria - 1896 (12 open before 1900, 22 since)
Tasmania - 1902 (3 open before 1900, 5 since)
Northern Territory - 1889 (3 open before 1900, 1 since)
Queensland - 1908 (2 open before 1900, 52 since)
South Australia - 1892 (12 open before 1900, 6 since)
WA - 1902 (16 open before 1900, 20 since)



Urban Heat Island

Urban development replaces natural surfaces and vegetation with heat-absorbing materials such as roads, footpaths, roofs and buildings, resulting in what is known as an Urban Heat Island influence on natural temperatures.

UHI is likely to have influenced some Australian temperature recording locations before 1940, particularly in cities and large regional towns, but the sparsity of motorised transport, asphalt and concrete construction during this era suggests the influence would be minor compared to modern urban environments.

It is possible that the UHI influence on temperatures was already fully developed at various but not all locations by the first year of recordings in the CSIR, Year Book, RAW and ACORN datasets.

In 2012 and 2013 it was anticipated that UHI warming in south-eastern Australia will continue to intensify by approximately 1C per decade over and above that caused by global warming (Voogt 2002), with tests in 1992 showing a UHI influence up to 7.2C between the Melbourne CBD and rural areas (source).

Smaller but significant UHI influences were found in regional towns, with a 1994 test observing a UHI intensity up to 5.4C between the centre of a Victorian town and its rural outskirts (source).

The proportion of ACORN locations in built-up environments fell from 67% in 1930 to 38% in 1970 and 20% in 2010. The shift away from urban centres accounts for some of the systematic differences between the ACORN dataset and analyses derived from raw data (source).



Discussion

Comparison of 44 Australian stations in the Year Book 1911-40 with long-term BoM RAW mean temperature averages to 2014 at those same locations shows no change, and no change in averages at the same locations selected from the <1931 CSIR dataset.

The mean temperature in the new millenium of 2000-2014 was 0.4C warmer at the 44 locations from the 1800s to 1931, and from 1911 to 1940.

Compared to 226 stations in the CSIR dataset, the average long-term RAW mean temperature at the corresponding locations from opening to 2014 was 0.2C warmer, and the period 2000-2014 was 0.5C warmer rounded or 0.4586C warmer exactly.

There are 19 corresponding stations in the Year Book and ACORN datasets during 1911-40 and their ACORN mean temperature during that climate period cool the original temperature by 0.6C.

There are 79 stations corresponding in the <1931 CSIR and ACORN datasets which indicate 0.5C mean temperature warming from the 1800s-1931 to 2000-14, which is approximately half the rate estimated by ACORN.

Based on known years of installation, about two thirds of temperatures in the CSIR dataset were recorded in Stevenson screens. Published estimates of Glaisher/Greenwich/open shade temperature influence suggest an insignificant bias below 0.1C on the overall averages, so the original records do not need adjusting.

Apart from thermometer screen shelters, another common artificial element likely to influence temperatures over time is UHI from urban development. This is more likely to influence recent rather than historic temperatures and published tests from the early 1990s show an upward bias of several degrees between some central and outer city or town locations.

The proportion of ACORN stations in urban rather than rural locations, mostly airports, fell from 67% in 1930 to 20% in 2010. This may have lessened the influence of UHI, dependent upon saturation levels at the original urban sites and acknowledged UHI that also occurs in airport environments where many of the thermometer stands were relocated.

Comparison of 66 stations that recorded from the 1800s to 1931 in the CSIR dataset suggests ACORN cooled original temperatures by 0.3-0.4C during 1910-1931.

This may be due to warmer temperatures before 1910 or a downward adjustment of station temperatures before 1931 in ACORN to compensate for non-Stevenson screens and other artificial factors that might otherwise inflate early records.

A 0.3-0.4C cooling is not warranted by screen shelter influence and is a significant reduction if the cause is UHI compensation for station relocations to non-urban areas.



Conclusion

Downward ACORN adjustment of historic temperature records from weather stations before 1940 adds 0.3C or 0.4C to Australia's rate of climate warming since 1910 but the reason for the downward adjustments is unclear.

Various timescale and station comparisons show insignificant changes or warming up to 0.5C from <1931 to 2000-14. These temperatures from 1855 to 1940 are compared to what the BoM describes as the hottest decade ever recorded in Australia (2014 claimed as the third hottest).

Other historic documents add weight to the evidence that pre-1910 temperatures were not significantly cooler than current readings.

For example, On the Climate of the Yass-Canberra District published in 1910 by Commonwealth Meteorologist Henry Hunt shows temperatures at 10 locations were on average 0.1C warmer in all years before 1909 than in 2004-2013. Hunt also presents <1909 summer and winter mean temperatures at six northern Australia locations which average 0.2C warmer than those locations in 2004-2013 (download PDF).

Henry Hunt et al also published The Climate and Weather of Australia in 1913 showing temperatures recorded at various Australian capital city and regional locations prior to 1912. These suggest mean temperatures increased 0.50C from <1912 to 2000-2015 at 20 regional locations. See data.

The CSIR and Year Book temperature datasets are unadjusted records compiled by Australia's leading scientists and weather experts in the mid 20th century and are accurate but differ from BoM records that are adjusted in both RAW and ACORN.

Their dataset timescales include the first 85 years of temperature recording at most weather stations across Australia in a network more than twice as large as ACORN, and their averages are a legitimate historic record indicating climate warming has been significantly less than calculated with adjusted data since 1910.



Average monthly mean minima and maxima can be chart-viewed for a comparison of CSIR, Year Book and BoM CDO temperatures at the 44 Year Book locations. There are 21 ACORN stations in the 1953 Year Book that also have CSIR and CDO raw datasets, also allowing a chart comparison of average monthly minima and maxima.

Also see a comparison of rural stations in Year Book 1911-40 compared to RAW and ACORN recordings from 2000 to 2011.

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All data Excel spreadsheets download (2.3mb)

Thanks to Bill Johnston for aquiring Meteorological Data for Certain Australian Localities published by the CSIR and to Geoff Sherrington for conversion of Fahrenheit to Celsius


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