A man walks with an umbrella during hot weather
Bureau of Meteorology data shows Australia's climate has warmed by an average of 1.47C since 1910. Image by Kelly Barnes/AAP IMAGES

Climate claim BOMs in attempt to rewrite temperature history

Meghan Williams February 16, 2023
WHAT WAS CLAIMED

Temperatures in Australia have cooled over the last 100 years.

OUR VERDICT

False. Australia has been warming since national temperature records began in 1910.

A Facebook user has questioned the validity of climate science, claiming temperatures in Australia have been cooling over the past century.

However, the claim is false, and the opposite is true. Since reliable temperature recording began in 1910, Australia’s climate has warmed by an average of 1.47 degrees Celsius, give or take 0.24C.

The Facebook post (screenshot here) includes an image of an Australian map labelled “Some of the highest recorded daily maximum temperatures in Australia”.

Several temperatures, each with their apparent year of occurrence, have been plotted around the map, with some reaching as high as 53C in 1845.

A screenshot of the Facebook post.
 The Facebook post claims past high temperatures prove the climate in Australia is now cooler. 

The Australian-based user states: “So, to be honest, your so-called CLIMATE CHANGE in Australia started well over 100 years ago, if not further back and has actually cooled down a bit since then. BTW these are factual records from the Bureau of Meteorology”.

But a climate expert and Bureau of Meteorology (BOM) data confirm the opposite is true.

Joelle Gergis, a climate scientist at the Australian National University, ridiculed the post’s assertion.

“The claim that Australian temperature is cooling is absolute nonsense,” Dr Gergis told AAP FactCheck in an email, pointing to the BOM’s 2022 State of the Climate report.

The report states Australia’s climate has warmed by an average of 1.47C, give or take 0.24C, since 1910, with most of the warming occurring since 1950.

People in the water at Milk Beach in Sydney
 National temperatures have been increasing since reliable records began more than a century ago. 

The report says Australian national temperature records began in 1910. Prior to that year there was no national network of temperature observations and standardisation of instruments used to measure temperature had not been introduced.

Those factors mean it is difficult to construct a national average temperature – the method used to show climate trends for the country – in a way that is consistent with post-1910 techniques.

A BOM representative explained to AAP FactCheck that “working with early data is challenging, due to unstandardised instrumentation and observing practices before 1910 along with the relative sparseness of temperature records across the country”.

The BOM carried out research with national and state archives and “a range of pre-Federation observatories and historical societies” to digitise and extend “some of south-eastern Australia’s key meteorological records”.

“This work has shown that temperatures in the southeast between 1860 and 1910 were similar to those experienced during the first half of the 20th century,” the representative said via email, highlighting long-term temperature data. “This confirms that the warming trend observed in the Australian region since the mid-20th century has been historically significant.”

In sites where pre-1910 temperature records have longer histories and better data, such as in south-eastern Australia, experts have been able to reconstruct temperature trends.

The BOM’s annual climate statement 2022 reported that the national mean temperature was 0.50C warmer than the 1961-1990 average, “making 2022 the equal-22nd-warmest year since reliable national records began, in 1910”.

Cattle try to seek relief from the sun and heat.
 Cattle seeking relief from the sun during heatwave conditions. 

Dr Gergis also pointed to the Sixth Assessment Report, from the Intergovernmental Panel on Climate Change (IPCC), which evaluated Australian temperatures.

The report stated “there is very high confidence that the climate of Australia warmed by around 1.4┬░C and New Zealand by around 1.1┬░C since reliable records began in 1910 and 1909 respectively, with human influence an important driver” (page 1990).

The map of Australia included in the post appears to be from a blog by climate sceptic Jo Nova, who plotted the map with temperature readings reported in historical newspaper archives.

The BOM added that social media posts “rarely provide methodologies and data descriptions such as those required for scientific publication” making it difficult “to evaluate stated conclusions, or even what climate records have been used”.

AAP FactCheck has previously debunked multiple climate cooling claims – see here here, here and here.

The Verdict

The claim that Australian temperatures have been cooling over the last century is false. Data from the Bureau of Meteorology and the Intergovernmental Panel on Climate Change show that national average surface temperatures in Australia have been increasing since reliable records began in 1910.

False – The claim is inaccurate.

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