Monthly Archives: January 2020

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.

Gladstone – Case study

Dr Bill Johnston [1]

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

  • The weather station at Gladstone Radar marks the approximate southern extremity of the Great Barrier Reef.
  • Temperature and rainfall data are used to case study an objective method of analysing trend and changes in temperature data.
  • The 3-stage approach combines covariance and step-change analysis to resolve site change and covariable effects simultaneously and is widely applicable across Australia’s climate-monitoring network.
  • Accounting for site and instrument changes leaves no residual trend or change in Gladstone’s climate.

Background

In Part 1 of this series, temperature and rainfall data for Gladstone Radar (Bureau of Meteorology (BoM) site 39326) are used to case-study a covariate approach to analysing temperature data that does not rely on comparisons with neighbouring sites whose data may be faulty.

Advantages of the method are:

  • The approach is based on physical principles and is transparent, objective and reproducible across sites.
  • Temperature data are not analysed as time-series in the first instance, which side steps the problem of confounding between serial site changes and the signal of interest.
  • Changes in data that are unrelated to the causal covariate are identified statistically and cross-referenced where possible to independent sources such as aerial photographs and archived plans and documents. Thus the process can’t be manipulated to achieve per-determined trends.
  • The effect of site-changes and other inhomogeneties are verified statistically in the covariate domain. Thus the approach is objective and reproducible.
  • Covariate-adjusted data are tested for trend and other systematic signals in the time-domain.

Further, statistical parameters such as significance of the overall fit (Preg), variation explained R2adj and significances of coefficients provide an independent overview of data quality.

Click here to download the full case study 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 from 1971 to 1979.