This piece was originally commissioned as a response to a piece from Maurice Newman, which can be found here.
What is the difference between a genuine scientific sceptic (aka an agnostic) and a science denier? It’s simple: sceptics consider the full body of evidence before making up their mind. Deniers already have their mind made up and reject any evidence that conflicts with their pre-conceived views.
It’s not that difficult identifying denialist behaviour. The tell-tale characteristic is denial of the full body of evidence.
For example, there is an overwhelmingly strong case that humans are causing global warming. Many lines of evidence, taken from direct, real-world measurements, all point to a single, consistent answer. The heat-trapping nature of greenhouse gases has been known since John Tyndall measured them in the laboratory in 1859. Tyndall predicted the distinct climate fingerprints you’d expect to see from greenhouse warming.
A century and a half later, these predictions have been confirmed by modern observations. Just as Tyndall anticipated, winters are warming faster than summers. Consistent with greenhouse warming, nights are warming faster than days.
A number of additional human fingerprints have been observed throughout our climate. More heat is being observed returning back to the Earth’s surface, at the exact wavelengths that greenhouse gases absorb energy. Another pattern of greenhouse warming is a cooling upper atmosphere while the lower atmosphere warms. This has also been observed.
And a smoking gun that emphatically points to human causation comes from satellites measuring less heat escaping to space at those same greenhouse wavelengths. The scientists publishing this research described this as "direct experimental evidence for a significant increase in the Earth's greenhouse effect".
Taken together, these fingerprints rule out other possible causes of global warming such as the sun, ocean cycles or Svensmark’s cosmic ray theory. In fact, in the last few decades of global warming, sun and climate have been moving in opposite directions. The same goes for cosmic rays. Solar activity, if anything, has recently had a slight cooling effect – in a small way, offsetting the warming effect of rising greenhouse gases.
The genuine scientific sceptic considers the full body of evidence. Deniers squeeze their eyes shut, stick their fingers in their ears and in that state, find no evidence for human-caused global warming. The same, tell-tale pattern of science denial is observed whenever the question of whether global warming is happening comes up. Climate deniers claim global warming stopped in 2000 (or 1998 or 2001 or even 1995 depending on the day of the week).
To make this claim requires turning a blind eye to the full body of evidence. When scientists add up all the heat accumulating in the oceans, warming the land and atmosphere and melting ice, they find that since 2000, our planet has been warming at a rate of four Hiroshima bombs worth of heat every second. The laws of physics still operate after 2000 and are, in fact, still in effect as we speak. The greenhouse effect continues to blaze away and the planet continues to build up heat.
While the surface temperature warming trend has flattened somewhat in recent years, this can only be understood in light of all the evidence. When considered in the context of the planet’s continued build-up in heat, it becomes clear that the slowdown in surface warming is due to the oceans absorbing more than the usual amount of heat.
Temporary drops in surface temperature have happened throughout the last few decades of global warming. As the planet has steadily built up heat, surface temperature jumps up and down from year to year as the ocean exchanges heat with the atmosphere.
How do deniers react to the planetary build up in heat? By denying the empirical evidence.
They reject any ocean measurements that show the planet is building up heat. They laser focus on the upper layers of the ocean while denying any measurements indicating heat build-up in the several kilometres of ocean below 700 metres.
The preponderance of evidence has resulted in a consensus among the scientific community. Several surveys of the scientific community have determined that around 97 per cent of climate scientists agree that humans are causing global warming.
I was recently involved in a group effort to analyse 21 years of published climate research, with our results published in the peer-reviewed journal Environmental Research Letters. We found that among the papers stating a position on human-caused global warming, over 97 per cent endorsed the consensus. We also asked the scientists who authored the papers to rate their own research – this independent method also found a 97 per cent consensus that humans are causing global warming.
Our analysis is the latest in a series of studies (e.g., here, here and here) indicating overwhelming scientific consensus on the basic fact that human activity is disrupting our climate. We found over 10,000 scientists from over 70 countries publishing peer-reviewed papers endorsing the consensus. These scientists come from a range of disciplines including climate science, biology, chemistry, geology, paleoclimate and glaciology.
The scientific consensus is built on a foundation of empirical evidence and manifests in a diverse community of scientists spanning a range of disciplines in countries all over the world.
How is it that people deny the many lines of evidence for human-caused global warming, turn a blind eye to the astounding build-up in heat and reject the scientific consensus? The various movements that deny a scientific consensus all have a number of characteristics in common. A common technique is cherry picking of the data, for which we’ve already seen several examples.
Another characteristic of all movements that reject a scientific consensus is the inevitable clinging to desperate conspiracy theories. For example, many deniers of the link between AIDS and HIV believe that AIDS was created by the US government.
The tobacco industry accused the scientific consensus linking smoking to cancer of being a “a vertically integrated, highly concentrated, oligopolistic cartel" which "manufactures alleged evidence, suggestive inferences linking smoking to various diseases, and publicity and dissemination and advertising of these so-called findings."
Most climate conspiracy theories derive from a batch of private emails stolen from the University of East Anglia in 2009. The conspiracy theories are generally constructed by taking quotes out of context to imply a nefarious plot by climate scientists to falsify data. However, since the theft of the emails, nine independent enquiries by government and university bodies in the UK and USA have scrutinised the emails. Every single investigation found no evidence of wrongdoing by climate scientists.
So what was found in these investigations? The US Environmental Protection Agency discovered “simply a candid discussion of scientists working through issues that arise in compiling and presenting large complex data sets.”
You would think nine independent investigations by a range of organisations across two countries would allay the concerns of conspiracy theorists. However, a key characteristic of conspiracy theorists is that any evidence against their conspiracy theory is regarded as further proof that the conspiracy exists. Consequently, each time a new investigation concluded that there was no climate conspiracy, climate deniers responded by broadening the conspiracy to include the investigators.
Climate ‘sceptics’ are anything but genuine sceptics. They deny the full body of evidence, they cherry pick the data and they indulge in vast, implausible conspiracy theories involving tens of thousands of scientists across a range of disciplines from countries all over the world. They believe a few out-of-context quotes from stolen emails can overturn the laws of physics and 150 years of scientific research.
Sadly, this behaviour shouldn’t surprise anyone. It is exactly the type of behaviour expected from any movement that denies a scientific consensus built on a preponderance of evidence.