Somebody named Ronald Bailey (he isn’t anybody I know) at the inaptly named Reason asked the good question which heads this post.
Second thought: the question is awful. No scientist I know disputes “Man-Made Climate Change Is Real”. None. What scientists like myself do dispute is that man-caused changes to climate are well understood and predictable. And I have proof.
But the idea behind Reason’s query is still good, even if Bailey himself doesn’t understand much about his subject.
Everybody out of love with any scientific theory should be prepared to say what it would take for amour to flourish. Just as everybody infatuated with a hypothesis should be able to state what would dim their ardor.
This does not only go for skeptics of global-warming-of-doom, but also for proponents. Tell us, if you dare, what would convince you that you’re wrong. I’m answering the question below, but I also insist you answer it, too. If your answer is of the form “Shut up”, “I don’t have to answer”, or “Your answer, Briggs, wasn’t to my liking, and here’s why”, as it is expected to be for many progressives, congratulations. You’re a True Believer. (Appell, I’ll even let you answer.)
I have already changed my mind about global warming. I was initially a believer that bad times were on their way. Why? Well, I was young, fresh to the field. I knew how smart my betters were; I knew how wonderfully complex their models could be; I saw the increasing success in weather forecasting and the improvements in short-term (out to a year or so) climate predictions.
The temperatures, back then, were on their way up, too, in accord with what some climatologists were predicting. I never made the mistake, like Bailey, to count the same piece of evidence more than once. Rising temperatures were consist with the theory that increasing CO2 caused increasing temperatures. But a melting glacier is a consequence of that heating, it is not additional proof of the theory. What an elementary mistake to think it was! Likewise, nothing that was a consequence of increased temperatures counts as additional evidence of why the increased happened.
That I saw people making these mistakes, in a big, enthusiastic way, was what started my path back to Truth. How many papers announced “This evil will befall us once the temperature increases past the point of no return”? Thousands; more; they continue in a steady stream. And all of them were taken as evidence that the CO2-theory was right.
That being impossible, and stupid, I began seriously looking into the problem.
That’s when I noticed climate model forecasts had no skill. Before, I merely took it for granted they had. The predictions models made were not as good as saying “next year will look like last year”, i.e. persistence. The models were poor globally, and even worse locally. The temperatures, for some two decades now, are not going in the direction the models promised.
This can only mean that the models were (are) broken. Why? Well, the theory which underlies them must be busted. Where? Who knows? It could be many things, or just one big thing. It’s not my job to find out, either. Though I and some pals of mine have some guesses.
Your car doesn’t start. You can then authoritatively state, “My car is busted.” It would be asinine and unscientific to say, “Even though my car doesn’t start, it really does work and really is taking me places.” Yet that is what supporters of the current models are saying. The models don’t work but proponents still claim they’re still taking us to the future. This is a form of politically correct lunacy.
But therein lies my answer to the question. I would change my mind and believe the models had a good, and not a dismal, handle on reality if they were to start making good predictions. About the future.
I had to add that, what seemed unnecessary, “About the future” because of the unfortunate habit of some modelers to claim their models make good “forecasts”—-of the past. Yes, they do this. It’s called “hindcasting” or “backcasting”. It’s a way of testing model fit with observed data. It can be useful to discover wild or egregious flaws in models, but no matter how well a model hindcasts, it’s no guarantee it will make good future-casts.
Future-casts, i.e. predictions, are the only test. There is none other. And models have so far failed that test.
But if they were to pass that test, and pass it consistently, then I’d have to believe the models were on to something, and that the theories which drive the models are likely true.