Consensus is a loaded term in any conversation about climate change. On the one side, we hear claims that 97% of climate scientists believe the earth is warming, and we're the primary reason. On the other, a stubborn and determined band of skeptics loudly deny that this is the case.
First, let me state upfront what my position is. I believe climate change is real, it's mostly our fault, and the scientific evidence to support these claims is overwhelming.
But is the consensus really 97%?
Technically, no, but arguably, yes. As I'll show below, the number is still high enough that, in other scenarios, we wouldn't hesitate to take action.
Below is a chart listing some other studies that have looked at the level of consensus among different specialties within the earth sciences. This chart comes from a follow-up study published in 2016 by John Cook et al. that looked at the results from several studies addressing the climate change consensus issue. This study ranked the level of expertise in climate science on a scale from 1 (lowest) to 5 (highest).
They found a range determined mainly by the level of expertise of the group. Economic geologists and non-publishing climate scientists were the most skeptical, showing less than 50% support for the idea of anthropogenic climate change. However, as you increase the level of expertise and experience in the field, the consensus builds.
Take a look.
Based on this study of studies, I'm confident that at least 80% of the experts in climate science are on board with anthropogenic climate change.
"Ha!" You may say, "but it's not 97%!"
True enough, but answer me this.
What if your cardiologist told you that, based on the multiple tests she had conducted, you were on the road to an eventual heart attack. What would you say?
"Prove it!"
Fair enough.
So she tries. First, she says several lifestyle indicators put you at higher risk. You are thirty pounds overweight for your age and lead a sedentary lifestyle. Your diet is unhealthy, full of foods rich in saturated fat and cholesterol. Moreover, moving beyond these lifestyle indicators, she tells you the troubling results of some tests that confirm her suspicions. Your blood pressure is 160/100. Your LDL cholesterol is 190. The electrocardiogram and MRI tests showed some disturbing anomalies in your heart that warrant further testing. Your doctor says you are in danger, maybe not right now, but sometime in the coming years if you don't make some significant changes.
While this news makes you very uneasy, you decide to get a second opinion. You suspect that your doctor is just in it for the money. You feel fine, so why all the fuss? Sure, you get short of breath more and more these days and have some chest pains now and then, but those are just natural occurrences in any adult body.
Yet the next cardiologist pretty much tells you the same thing. You don't like that either. You muse that this doctor probably talked to the first one and is therefore in cahoots. This one is also probably just in it for the money. They all are! So you keep going to different cardiologists, ten all told, to get more opinions. In the end, 8 out of 10 say more or less the same thing that the first one did.
Of the two dissenters: one is an older, experienced cardiologist whose views on heart health are very controversial within the medical community. He tells you saturated fat and cholesterol are not bad for your heart but actually good. Also, exercise is totally overrated. He says all you need to do is engage in positive thinking through meditation and mindfulness. The body will then naturally heal itself over time. While his credentials are impressive, you are unsure what to think when you leave the consultation.
The other dissenter is a charming, retired cardiologist who supplements his income as a paid consultant to Frito Lay and KFC. He waves off the other eight cardiologists' concerns as excessive fear-mongering from a bunch of know-it-alls who don't know nearly as much as they think. He tells you that he has eaten fried chicken and potato chips his whole life with no health problems at all. Don't worry about it, he assures you. You only live once, so don't live in fear!
Still, you can't get around the fact that most of the doctors you see tell you that your lifestyle is putting you at risk. You need to change. While they cannot say how bad it will get, or even how soon, they know the risk factors are significant. Doing nothing will likely have catastrophic implications on your health in the future.
What do you do at this point?
I know what I'd do. I'd listen to the consensus. And unless you're an idiot, you would too.
My point here is that, in this case, an 80% consensus feels like a pretty solid majority to put trust in, especially if one's long-term well-being and health are at stake. Only an arrogant fool would pretend to know better.
Shouldn't the same go for climate change?
Let's say the climate change consensus is only 80%. I think the real number is somewhere in the 90s when you narrow it by expertise, but for the sake of argument, let's say it's "only" 80%. Is that still not high enough for you to support some significant political approach to addressing the issue? If the answer is no, I'd ask a couple of follow-up questions.
Then what level of consensus would it take to convince you, and from what sources?
Why not the climate researchers at NASA, NOAA, and the IPCC, since their expertise is second to none. And if not them, then who do we trust?
Ourselves?
No thanks.
One other thing: Don't confuse a lack of public consensus with a lack of scientific consensus. Be suspicious of your intuitions if they radically clash with the expert consensus. A good rule of thumb is to take seriously the possibility that maybe, just maybe, you're the one who is wrong. Perhaps there's something you're missing? After all, most of us defer to medical expertise when it comes to our health.
Why is this? Because everyone shares the same primal fear of death and urge for self-preservation, even when our habits undermine us. When our doctor tells us that we need to change or something terrible may happen, most of us listen. We then make prudent changes, knowing that we'll pay later if we don't do it now.
So it should be with our planet. We can treat it like garbage, as merely a means of giving us what we want when we want it, damn the consequences. Or, we can listen to the warnings of our own planet's cardiologists and then adjust before it's too late.
I'm only arguing that we should treat our planet - the body we all share - in the same way that our doctors recommend we treat ourselves: with profound respect and care.
And like our bodies, we're stuck with the one planet we have.
We should take care of it.
Or else.
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Garmisch, Germany
February 2020