Scientists Take Australian Bureau of Meteorology to Court Over Reliability of Temperature Records

By Nina Nguyen
Nina Nguyen
Nina Nguyen
Nina Nguyen is a reporter based in Sydney. She covers Australian news with a focus on social, cultural, and identity issues. She is fluent in Vietnamese. Contact her at
February 7, 2023Updated: February 16, 2023

For years, Australian biologist Jennifer Marohasy has questioned the reliability of the Bureau of Meteorology’s (BoM) new methods of reporting historical weather records, which have shown a rising in temperatures over the past few decades. She wants the BoM to make public its sets of raw data from both mercury thermometer readings as well as electronic readings from updated automatic weather stations.

The BoM has attributed the increasing temperatures to manmade global warming, but Marohasy is sceptical, saying the recent warming trend could be attributed to changes in how temperatures are now recorded and the data standardised, as well as natural causes.

In response, her husband, environmental researcher John Abbott, took the matter to the Administrative Appeals Tribunal in Brisbane with Marohasy appearing as an expert witness. They called for the BoM to make raw temperature data public, something the weather bureau has refused previously.

A public hearing was held on Feb. 3, but the case was taken back to mediation before Marohasy presented her evidence. Further, the public was asked to leave. The case resumed on Feb. 7.

Raw Temperature Data Crucial to Understanding Climate Change

According to Marohasy, a major reason why Australia’s temperature data may have underlying issues leading to different interpretations is because of the changes in equipment used, resulting in the need for homogenisation to standardise the data between the measurement methods.

Previously, the BoM used mercury thermometers, which have a slow response to change. These have since been replaced with electronic sensors, which are more sensitive.

“The change from a mercury thermometer to a probe makes a material difference to the reliability of the historical temperature data,” Marohasy wrote in a blog post on Feb. 4.

“This matters for understanding climate variability and change—the trend.”

The concern was echoed by Queensland geophysicist and former professor at James Cook University Peter Ridd. Ridd said in a Facebook post on Feb. 2 that while mercury thermometers often missed short-term high temperatures, electronic probes “often pick up the short-term high temperature ‘spikes’ and thus register a higher maximum temperature on that day than the mercury thermometers.”

“So, has the bureau accounted for this in their long-term records?” he asked, “It could well mean that they are reporting temperatures higher than they should.”

In 2018, Marohasy shared a table comparing raw temperature readings and the two “homogenised” ACORN-SAT datasets, explaining that the data corrections have resulted in a “rewriting” of the temperature records of 112 weather stations dating back to 1910.

ACORN-SAT stands for the Australian Climate Observations Reference Network—Surface Air Temperatures.

“Temperatures are changed through a process known as homogenisation, and then changed again, sometimes by as much as 6.4 degrees Celsius (11.5 F) for the one day,” Marohasy wrote in 2019.

According to Marohasy, 44.8 degrees Celsius (112.6 F) was the maximum temperature measured at Albany, Western Australia, on Feb. 8, 1933. In the year 2012, BoM homogenised the maximum temperature to 51.2 degrees Celsius (124 F), before it was recently revised to 49.5 degrees Celsius (121.1 F).

Epoch Times Photo
Scientists John Abbot (L) and Jennifer Marohasy (R) outside the Administrative Appeal Tribunal in Brisbane on Feb. 3, 2022. (Jennifer Marohasy/ Facebook)

She noted that the release of the parallel data attained from mercury and electronic thermometers is important so that readings from the new equipment can be compared with readings from the old equipment, “including to check they are comparable—that there are no discontinuities.”

“It is reasonable to assume this data would be public, but it is guarded by the Bureau and kept secret. The Bureau also claim it is undigitized and only potentially available as hard copies of A8Forms and that the Bureau lacks the available resources for scanning to provide this on request,” she wrote on Feb. 4.

“Work that I have undertaken with John Abbot shows that even without the industrial revolution, there would have been a temperature increase of about 1 C (1.8 F) through the 20th Century.

The biologist further noted that release of the data “is in the public interest—given far-reaching public policy decisions are being made on the basis of a 1.5 C tipping point.”

Additionally, on Jan. 28, Marohasy argued that “claims that we are facing a climate catastrophe because temperatures will soon be exceeding 1.5 C is driving the closure of coal mines, caps on the price of gas, and a mental health epidemic amongst children who increasingly fear global warming.”

‘No Significant Difference’ Shown: BoM

In a statement to The Epoch Times, the BoM said, “there is no significant difference in the diurnal temperature range measured using mercury thermometers compared with platinum resistance probes.”

As to what the major factors contributing to the rise in Australian temperatures are, the BoM pointed to the State of the Climate Report 2022, recently released by the Bureau of Meteorology and the Commonwealth Scientific and Industrial Research Organisation (CSIRO).

In a Facebook post on Jan. 31, Marohasy said that despite the importance of the temperature data, there is a lack of media attention on the issue.

“It is of real concern to me that so many faux scientists, both sceptics and alarmists, are uninterested in the evidence, specifically the parallel data,” she said.

“They are uninterested because this evidence does not accord with the narratives that have developed on both sides. And they are not curious.”

“They don’t understand the evidence I present. And I suspect they are too busy to make the time to get across the evidence.”

“The established narratives do not generally include incompetence; rather, they focus on malfeasance.”

The Epoch Times has reached out to Marohasy but didn’t receive a response in time for publication.

Richard Szabo contributed to this report.

CORRECTION: A previous version of this article inaccurately described parallel data. The Epoch Times regrets the error.