Rewriting Australia’s Temperature History

This post provides a link to download as a PDF, Chapter 16 of Climate Change The Facts 2020, “Rewriting Australia’s Temperature History”, by Jennifer Marohasy.

The Bureau of Meteorology is one of Australia’s most important national public institutions; so much depends on our knowledge of past climate and our ability to predict future trends and events. The Bureau’s recordings of maximum and minimum temperatures across Australia provide information that is important to our understanding of such trends and patterns in a changing climate. The Bureau does not, however, simply report this information. Rather, complex remodelling is undertaken in the development and compilation of the official climate change statistics. In this chapter, I consider the results of the Bureau’s ‘homogenisations’ of historic temperature measurements through two case studies: Darwin and Rutherglen.

The Bureau undertook some remodelling in 2018 that increased the overall rate of warming by 23% between Versions 1 and 2 of the Australian Climate Observations Reference Network − Surface Air Temperature (ACORN-SAT) database (Trewin 2018). The Bureau claims that this remodelling of temperatures is justified for two reasons: because of changes to the equipment used to record temperatures; and because of the relocation of the weather stations. However, there have been no changes to equipment and no relocations since the release of ACORN-SAT Version 1 for either Darwin or Rutherglen.