I have written before about the problem of what can and cannot be known about climate change, given that we only have one planet to experiment on, and our simulations will never be accurate beyond question. Here is another expression of the same basic idea. I am trying to figure out the most effective way to convey this information to people who don’t think we should be taking aggressive action on climate change.
This chart shows four possible situations that humanity could find itself in, 100 years or so from now. Either climate change has been disastrous or it has not been, and we either took strong action to deal with it or we did not:
As you can see, there is only one situation in which we can be absolutely sure we made the right choice. Even that is a bit ambiguous, though. Imagine the decision isn’t about climate change but about Russian Roulette. If we are alive after the game, but we did choose to play, can we really be said to have behaved prudently? The sheer fact that the chamber didn’t turn out to be loaded doesn’t mean that we were intelligent to run the risk, back when we didn’t know that for sure.
Imagine two snakes, both of which look very similar. One is deadly venemous, and the other is benign. If the best information we have at hand suggests that there is a good chance we are dealing with the venemous one (say, because we are in the region where it usually lives), the prudent thing is certainly to behave as though the snake may be venemous. Even if you learn later that it was not, nobody will think you were a fool for acting that way. The climate science we have now is providing good reasons to think that we are dealing with a deadly snake of a problem.
In short, the science will never be settled in the sense that it will tell us exactly what to do. All it can do is become clear enough to make the prudent choice obvious to most people.