Climate Change Scientists, Critical Thinkers?

It seems logical to me and probably most people that scientists are going to be some of the most critical thinkers. And this is also their claim, but I am a little confused when it comes to discussions about climate change why so much critical thinking *seems* to be missing. I’ll explain what I mean.

I first have to admit that my knowledge of the science behind climate change is limited. I’m no expert. There are some interesting climate related things happening in the world so I can go along with the idea that maybe something is up, however, when it comes to proving that the changes are *all* due to the affect humans have on the planet, I become a big skeptic. I’m just not much into believing every alarmist and his impassioned story just because it plays to fears of global devastation (who doesn’t love a good Armageddon story).

Ok, so here’s what I mean when I say that the critical thinking seems to be missing. I’ve read parts of the IPCC Fourth Assessment Report on Climate Change. What is so striking to me is what terminology is used to express the certainty from this group that climate change is caused by humans (anthropogenic). Here’s what the report says in the footnote on page 4 of the Working Group Summary for Policy Makers (PDF), just so we’re clear on terminology:

In this Summary for Policymakers, the following terms have been used to indicate the assessed likelihood, using expert judgement, of an outcome or a result: Virtually certain > 99% probability of occurrence, Extremely likely > 95%, Very likely > 90%, Likely > 66%, More likely than not > 50%, Unlikely < 33%, Very unlikely < 10%, Extremely unlikely < 5%. (See Box TS.1.1 for more details).

Now maybe I’m just the dummy here and everybody else gets it, but I don’t understand how one can have such a high level of certainty when their assessment is based simply on using expert judgment.

In a court case someone who has knowledge in a particular field will be called an “expert witness” and their testimony will often be accepted as fact because of their knowledge and experience in that field. Ok, so I suppose we should apply the same thing here. We should simply accept that the people who have decided these things are experts and their judgment should be considered fact. There’s only one problem with that. The field we’re talking about is so new and unknown we would be foolish not to question the validity of anyone’s *expert* testimony on either side of the debate.

For those of you who are upset at this point because you feel I just don’t get it, please enlighten me. I don’t want a pointless debate. I want to learn and understand. On what basis do we blindly accept the testimony of these experts? Not only that, how is it that they can simply arrive at such a specific percentage of certainty? From what I’m told there are computer models out there that can demonstrate this certainty, but if that is true, then why don’t we see statements in the report that say “90% certainty based upon computer modeling and calculations”. Why do we just get, in essence, “90% certainty based upon some smart dude’s expert judgment”?

Does that sound like critical thinking to anyone? If you tell me to just blindly accept what these people say as truth, I’m going to have a hard time considering your position valid. It sounds like blind faith to me and as everyone knows, scientists cannot accept blind faith. They need critical evidence. Don’t they? Otherwise, isn’t this just a religious debate? If I said to an atheist, “I’m 90% sure that God exists because I’ve known him all my life”, he wouldn’t accept my testimony even though I’ve *demonstrated* that I’m an expert on God (e.g. I’ve known him all my life).

And while we’re talking about evidence, can someone explain to me how computer models are able to determine which molecules or particles in the atmosphere come from fossil fuels and which ones come from natural sources created by the earth itself? I understand that trends since 1750 suggest that it’s warmer now than it was then, but we don’t have much in the way of climate data prior to that date. Isn’t it possible that warming occurred at another time earlier in the earth’s history that was clearly not due to the industrial revolution?

Wouldn’t a stronger case be made if we could go up into the atmosphere and take measurements and be able to conclusively say “well, these particles over here are from Acme Manufacturing while these were caused by those gases coming from that volcano over there and there’s clearly more coming from Acme”? Do we have this kind of technology? If we do, then great. Let’s see the data from those tests.

Call me crazy, but I think the jury is still out on the actual certainty of whether climate change is anthropogenic. If you show me some evidence to the contrary aside from, “the expert is pretty sure–90% sure even”, then I’ll be glad to hear it. Meanwhile, lets stop with the fear mongering over something for which nobody seems to have absolute unquestionable evidence. Shouldn’t we require at least a scientifically *provable* (as opposed to arguable) level of certainty before we go requiring countries to reduce emissions to some arbitrary standard that may or may not make a difference even if the problem is caused by us?