This article was reposted from Climasphere.org.
Last week, former Australian Prime Minister John Howard gave a speech on climate change for the Global Warming Policy Foundation, a conservative think-tank opposed to policies that mitigate climate change. Howard characterised scientists who accept the evidence that humans are disrupting climate as religious zealots. Consequently, he is not so convinced of the scientific evidence. On what does he base his views? Howard states that “…I instinctively feel that some of the claims are exaggerated.”
Howard is guided by gut feeling rather than empirical evidence and physics. At the same time, he accuses scientists, who arrived at their position through methodical consideration of the full body of evidence, of ideological bias. How does one make sense of this? An appropriate starting place is the scientific research into the biasing influence of ideology.
There are many factors that influence our climate change knowledge and attitudes, including education, scientific literacy and personal experience. Political ideology has a significant influence on climate change beliefs. A striking demonstration of the powerful effect of ideology is the finding that as education levels increased, Democrats became more concerned about climate change while Republicans became less concerned. Ideology rather than education is the hand at the wheel driving climate attitudes.
Does this mean ideological bias is symmetrical, with liberals exaggerating the effects of climate change while conservatives downplay climate impacts? Again, we can consult empirical research for the answer.
Scientific consensus is a good place to start. Over the years, a number of studies have found that among publishing climate scientists, 97% agree that humans are causing global warming. I was part of a team that performed the most comprehensive analysis of global warming research to date, examining 21 years worth of peer-reviewed papers studying climate change. We found that among papers stating a position on human-caused global warming, 97.1% endorsed the consensus on human-caused global warming.
Given the robust evidence for overwhelming scientific agreement, you might find public perception of consensus a little surprising. A 2012 Pew survey of Americans found that only 58% of Democrats believe scientists agree on global warming, while even fewer Republicans (30%) think there’s scientific agreement. Among Democrats, whom John Howard believes are biased towards climate alarmism, there’s a significant gap between public perception and the 97% consensus. However, the result that jumps out from this research is one simple fact. The more politically conservative a group is, the further its perception of consensus diverges from reality.
The human contribution to global warming is a key climate metric. The latest IPCC report estimated that of the 0.6°C of global warming since 1950, the best estimate for the human contribution is approximately 100%. If anything, it’s likely to be slightly over 100% with natural influences such as internal variability or the cooling sun offsetting some of our greenhouse warming.
What do the general public think on this key question? In a survey of representative Americans conducted earlier this year, I asked participants to estimate the human contribution to global warming. People on the left side of politics estimated the human contribution at 56% while those on the conservative right thought humans only contributed 32%. This further demonstrates that liberals are underestimating the human influence on global warming. Moreover, when it comes to climate science, conservative ideology is associated with greater departure from reality.
Australia’s current Prime Minister, Tony Abbott, continues to display the same evidence-free, gut-feeling bias against climate science as his predecessor. He dismisses the disruptive effects of carbon dioxide because it’s an invisible gas. The irony of this position is that carbon dioxide’s invisibility is a key feature of the greenhouse effect. He also dismisses the link between climate change and bushfires, arguing that bushfires have happened throughout Australia’s past. This logical fallacy is equivalent to arguing that smoking doesn’t cause cancer because people contracted cancer before cigarettes were invented.
When John Howard invokes his gut feeling against climate science, he reveals his own ideological bias. His accusation of liberal bias on the climate issue is an inversion of the true state of affairs. In the case of climate change, conservatism has an unreality bias.
UPDATE 14 Nov: Some comments were made about whether John Howard used the term "religious zealots" in his speech. His exact words were:
"I've deliberately chosen the title for the lecture One Religion is Enough to highlight my belief that part of the problem with this debate is that to some of the zealots in the debate, their cause has become a substitute religion."
Consequently, I've removed the quotations from around the term "religious zealot", which otherwise are a pretty fair characterisation of what Howard was seeking to communicate.
Posted by John Cook on Wednesday, 13 November, 2013
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