Climate at Cairns

Dr. Bill Johnston

Dr. Bill Johnston ‘s scientific interests include agronomy, soil science, hydrology and climatology. With colleagues, he undertook daily weather observations from 1971 to 1979.

Abstract

Main points

  • Like many historical datasets, conditions affecting temperature measured at the Cairns post office are largely unknown. Site changes in 1900 and 1924 occurred in parallel with observations and an objective statistical method and post hoc attribution of changepoints as detailed previously for Gladstone Radar is preferable to relying on incomplete and possibly misleading metadata.
  • Metadata incorrectly specifies the location of the original aerodrome site near the 1939 Aeradio office and ignored the move to the mounded-site near the centre of the airport in 1966 and also that the site moved in September 1983 out of the way of a new taxiway. During construction when neither site was operational, aerial photographs show a fourth site was established near the location of the current automatic weather station. Data from that site either in-filled the record or were used to adjust for the 1983 move. A highly significant step-change in 1986 plausibly marked when in-filling or adjustments ceased.
  • Rainfall reduced Tmax 0.033oC/100 mm and together with site changes accounted for 53.7% of Tmax variation. Step-changes at the post office in 1900, 1924 and 1929 and at the airport in 1986 caused 1.01oC of warming in the data and there is no residual trend or change attributable to the climate.

Background

Cairns is located in northern Queensland and is the main tourist-hub for visitors to Port Douglas, the wet-tropics hinterland and the northern Great Barrier Reef (GBR). It is often in the news that survival of the GBR is threatened by climate change warming and following a coordinated ‘save the reef’ campaign in April 2018 the Great Barrier Reef Foundation was gifted almost $0.5b by then Prime Minister Malcolm Turnbull. While WWF and related entities including AYCC, GetUp! and the Climate Council continuously bang the same drum, the question remains: to what extent is the climate of the GBR changing or warming?

The best way to find out is to grab some data, undertake research and find out what is going-on.

Merged in October 1942, one hundred and twenty years of post office and airport data showed no evidence that the climate at Cairns has changed or warmed. No marked increases have occurred in the frequency of maximum temperature extremes and nothing suggests temperature is likely to increase markedly in the future.

Being a whole-of-government enterprise, climate change and warming has been created by Bureau of Meteorology scientists who ignored site changes that happened and adjusted for some that didn’t to cause warming in homogenised data that doesn’t exist. ACORN-SAT metadata claimed the only move at the airport was in December 1992 when the “site moved 1.5 km northwest (to the other side of the runway)”; which isn’t true. Picked-up by the ABC, The Conversation, Guardian, the former Fairfax press; numerous web-sites and professors dependent on funding from the Australian Research Council; it has all rested on an extremely dubious, and superficial, level of statistical analysis. It must surely be deeply concerning to any competent statistical analyst that the Bureau of Meteorology BOM) has only the most rudimentary knowledge of site changes at Cairns – site changes that have created significant step changes in the data. Exhaustive research into historical Public Works records reveals significant site changes affecting the temperature record at Cairns.

It is of concern that so much money has fallen out of the sky to address a problem that cannot be confirmed by a rigorous analysis of the data.         

Click here to download the full paper including photographs and tables of data used.

[1] Dr. Bill Johnston’s scientific interests include agronomy, soil science, hydrology and climatology. With colleagues, he undertook daily weather observations between 1971 and 1979.

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