A Facebook user claims there has been no increase in Australia’s average temperature over the past 10 years, attempting to downplay carbon dioxide’s contribution to global warming.
However, this is not true. Australia has warmed slightly over the past decade and experts say a longer time period is required to identify temperature trends, which clearly show a rise.
The post was shared to a climate change denial Facebook group on August 16.
“No net warming in Australia for the past 10 years. And the Great Barrier Reef has more coral cover this year than ever recorded. The case for CO2 being the control knob of global temperature gets weaker every day. (Moore),” the post states.
The post quotes Patrick Moore, who made the claim on Twitter and other social media platforms. Mr Moore is a director of the CO2 Coalition, a nonprofit organisation that aims to educate policymakers and the public about the “important contribution made by carbon dioxide to our lives and the economy”.
He describes himself as a co-founder of Greenpeace but the environmental group refutes this claim. In 2010, it issued a statement saying: “Although Mr Moore played a significant role in Greenpeace Canada for several years, he did not found Greenpeace”.
Mr Moore’s social media posts include a graph from a Quadrant article on August 14 depicting University of Alabama in Huntsville (UAH) satellite data for Australian temperature in the lower troposphere (TLT), with the heading: “No linear warming trend for 10 years”.
Mark Howden, a professor at the Australian National University’s Institute for Climate, Energy and Disaster Solutions, says this is incorrect.
“Looking at the raw data, 2012 was 22.04C and 2021 was 22.36C. So even doing a … year vs year comparison, there has been an increase in temperature,” he told AAP FactCheck via email, referencing Bureau of Meteorology (BOM) figures.
“It is important to note that both 2012 and 2021 were La Niña years – which are normally significantly cooler in Australia because of the increased cloud cover and possibility of increased rainfall (which both cool down the land surface).
“So they show substantial deviations from the average temperature.”
Andrew King, a climate scientist at the University of Melbourne's School of Geography, Earth and Atmospheric Sciences, also confirmed Australia warmed in the past 10 years.
"But because we have high year-to-year variability in temperatures we look at longer periods to identify trends," Dr King told AAP FactCheck in an email.
"The warming trend in Australia becomes more apparent looking back further."
Prof Howden agreed.
"When we do that the increasing temperature trends become even stronger. In the case of the 30-year linear regression, the temperature has gone up almost 0.9C," he said.
"In climatological terms, this is a large increase."
Australia's BOM uses annual air temperature anomaly data to illustrate Australian climate variability (chart below).
Temperature anomalies are a positive or negative deviation from a long-term average and are typically used over raw data because they are representative of a much larger region and factors such as station location or elevation have less of an impact.
Professor David Karoly, an expert on climate variability also from the University of Melbourne's School of Geography, Earth and Atmospheric Sciences, said the UAH TLT data only supported the claim because the dates were cherry-picked.
However, Prof Karoly said the UAH dataset showed a clear warming trend when plotted over a longer period.
"The UAH TLT v6.0 (2022) dataset is available since 1979 and shows an average warming trend for Australia of 0.18C per decade over the period from 1979 to July 2022," he told AAP FactCheck in an email.
Prof Karoly says BOM data shows "a clear warming trend of about 0.8C across Australia from 1979 to 2022, also consistent with but slightly larger than from the UAH TLT data".
He also noted independent surface temperature data from Berkeley Earth showed a warming trend of about 0.7C across Australia for the same period, consistent with the weather bureau and UAH TLT data.
Prof Howden said ultimately any analysis would provide the same results, "that Australia is warming and the overwhelming evidence is that this warming is due to human emissions of greenhouse gases and other perturbations to our atmosphere".
AAP FactCheck has previously debunked other claims about temperature trends here and here.
The Verdict
The claim Australia has not experienced any net warming over the past 10 years is false. Comparing 2012 to 2021, temperatures rose from an average of 22.04C to 22.36C. Experts told AAP FactCheck that temperature trends need to be measured over a longer period and long-term data sets show a significant warming trend across Australia.
False - The claim is inaccurate.
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