The notion that climate science denial is no longer a part of Australian politics was swept away yesterday by One Nation Senator-Elect Malcolm Roberts.

In his inaugural press conference, Roberts claimed that “[t]here’s not one piece of empirical evidence anywhere, anywhere, showing that humans cause, through CO₂ production, climate change”.

He also promoted conspiracy theories that the CSIRO and Bureau of Meteorology are corrupt accomplices in climate conspiracy driven by the United Nations.

His claims conflict with many independent lines of evidence for human-caused global warming. Coincidentally, the University of Queensland is releasing a free online course this month examining the psychology and techniques of climate science denial. The very first video lecture addresses Roberts’ central claim, summarising the empirical evidence that humans are causing climate change.

Scientists have observed various human fingerprints in recent climate change, documented in many peer-reviewed scientific papers.

Satellites measure less heat escaping to space at the exact wavelengths at which CO₂ absorbs energy. The upper atmosphere is cooling at the same time that the lower atmosphere is warming – a distinct pattern unique to greenhouse warming. Human activity is also changing the very structure of the atmosphere.

Skeptical Science

Not only do these unique fingerprints confirm humanity’s role in recent climate change, they also rule out other potential natural contributors. If the Sun caused global warming, we would expect to see days warming faster than nights, and summers warming faster than winters.

Instead we observe the opposite: nights are warming faster than days, and winters are warming faster than summers, which is a greenhouse pattern predicted by John Tyndall as long ago as 1859.

Similarly, if global warming were caused by internal variability, we would expect to see heat shuffling around the climate system with no net build-up. Instead, scientists observe our climate system accumulating heat at a rate of more than four atomic bombs per second.

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Our scientific understanding grows stronger when many independent lines of evidence all point to a single, consistent conclusion. In the case of climate change, the “consensus of evidence” has led 97% of climate scientists to agree that humans are causing global warming.

The scientific consensus on climate change has also been endorsed by many scientific organisations all over the world, including the national science academies of 80 countries.

Skeptical Science

Is it a conspiracy?

How does one dismiss a global scientific consensus built on a robust body of empirical evidence?

There are five characteristics of science denial. These common traits are seen when people reject climate science, the benefits of vaccination, or the research linking smoking to cancer.

The techniques of denial are: fake experts; logical fallacies; impossible expectations; cherrypicking; and conspiracy theories. This is summarised in the acronym FLICC.

Climate science denial and conspiratorial thinking are often found together. A well-known example is that of Donald Trump, who has dismissed climate change by blaming it on a Chinese conspiracy.

@realDonaldTrump

Several studies have linked climate science denial and conspiratorial thinking. If a person disagrees with a global scientific consensus, they’ll typically believe that the scientists are all engaging in a conspiracy to deceive them.

Malcolm Roberts’ conspiracy theories have been well documented and were once again on offer in yesterday’s speech. He espouses a conspiracy that encompasses the CSIRO, Bureau of Meteorology, international banking families, the United Nations and Al Gore.

Unfortunately, I am not optimistic that the evidence for human-caused global warming will persuade Malcolm Roberts. The scientific evidence from psychology tells us that scientific evidence is largely ineffective on those who dismiss climate science with conspiracy theories.

My own research found that communicating the science of climate change to those who exhibit conspiratorial thinking can even be counterproductive, activating their distrust of scientists and strengthening their denial of the evidence.

Furthermore, conspiratorial thinking is self-sealing. When conspiracy theorists are presented evidence that there is no conspiracy, they often respond by broadening the conspiracy to include that evidence. In other words, they interpret evidence against a conspiracy as evidence for the conspiracy.

Our course on climate science denial will be much more useful to those who are open to scientific evidence and curious about the research into the causes and impacts of climate change and the psychology of climate science denial.