Why do we think that climate sceptics are irrational? A major reason is that almost none of them have any genuine expertise in climate science (most have no scientific expertise at all), yet they’re confident that they know better than the scientists. Science is hard. Seeing patterns in noisy data requires statistical expertise, for instance. Climate data is very noisy: we shouldn’t rely on common sense to analyse it. We are instead forced to use the assessment of experts.

So we think that experts should have much greater standing on these questions than non-experts. And we think that a consensus of experts is particularly good evidence for a claim. Famously, there is a near consensus among (relevant) experts about climate. The exact numbers have altered from study to study, but there is a consensus on the consensus: about 97% of climate scientists agree that the world is warming and that our emissions are largely to blame.

In response, climate sceptics sometimes argue there is no consensus, citing, for instance, an infamous petition allegedly signed by thousands of scientists rejecting the claims of man-made global warming. Even if the signatories to the petition are all genuine, and all have credentials in science (both claims are hard to verify), few have expertise in climate science: so the petition is entirely consistent with the 97% consensus claim.

The other favourite response from sceptics is to claim that the consensus reflects not a disinterested search for truth, but the influence of money. Climate scientists dare not dissent, because if they do, they will not receive funding from the granting agencies.

There is certainly evidence that money can corrupt science. A recent paper documents a case of this occurring. In the 1960s, the sugar industry paid Harvard scientists to carry out a piece of research that reached a predetermined conclusion: that fat, and not sugar, was responsible for heart disease. The resulting “research”, a literature review that claimed that the studies suggesting sugar was responsible had methodological flaws, was published in the New England Journal of Medicine. At the time, the journal did not require authors to declare conflicts of interests, and they didn’t.

Of course, it is not news that industry attempts to influence scientific findings. The case of sugar versus fat is an interesting one, because the industry was so successful in establishing a consensus. That fat is the main cause of heart disease, not sugar, became accepted by medical scientists. Publishing review papers in high profile journals is a good way to sway debates and establish claims. Once the claim was established securely in the minds of scientists, those who challenged it were dismissed as cranks. Might something similar be occurring in the case of climate change?

Parallels and differences

There are important differences between the case of sugar and that of climate change. The most important is the source of the funds: the money came from industry, which had a vested interest in the findings, not from granting agencies (whose reviewers have, at most, a commitment to validating knowledge, not a financial interest in it). That is not to say that these commitments cannot bias reviewers: they surely can. But the effect is likely weaker.

While there is extensive evidence for all sorts of cognitive biases, we remain capable of recognising the stronger argument and rejecting the weaker. Our biases are decisive only when the evidence is relatively evenly balanced and even then, we usually come round with the passing of time. When someone cynically manipulates data, though, they can bring all their intelligence and skill to presenting their case. The biased salesperson is a threat to our capacity to make good choices, but we should beware the conman much more.

The other difference is that in the case of climate change, there are buckets of money available to those who want to put forward a contrarian position. Scientists want to do science; that’s why they apply to granting agencies to fund them. But if they want to make real money and don’t care about the science then they should look elsewhere.

In fact, there are good grounds for thinking that the sugar case and the climate change case are parallel, not because in both cases money distorts the science by establishing a narrative, but because in both industry money distorts what the public believe. In the first case, industry money helped produce the scientific consensus, which was then disseminated to the public; in the second, industry money largely leaves the science unaffected but distorts public perceptions via other channels.

This is not to deny that the existence of a scientific consensus mightn’t make it more difficult for dissent to be heard. Scientists are human beings, and they are influenced by the need for respect from peers and their own biases. All scientific claims need to be subjected to searching scrutiny to avoid complacency. With regard to climate change, though, the scrutiny from dissenters has been constant and ongoing, and the science has emerged strengthened.

In conjunction with Oxford University’s Practical Ethics blog