By Matt Owens September 30, 2013
Climate scientists keep getting asked, "is this or that weather event caused by climate change?" And the scientists seem to hem and haw - and sometimes, they turn to an analogy. But these analogies, and really, the question of causality, are both two sides of the wrong coin. The questions and the answers leave the public with the wrong perception, and I think we can improve this situation.
Here's one of the most popular analogies for climate change and causality: a baseball player starts taking steroids. And soon enough, he's hitting twice as many home runs as before. The player is like our climate, and the steroids are like global warming. And the chance of hitting a home run is like the chance of having a severe weather event. But it's hard according to this analogy to say any specific event is caused by global warming. It's just that the risk of these events is increasing.
This analogy is useful - but only in a very narrow range of situations. Why? Because an athlete on steroids is fundamentally a different player. And this actually is the situation with our climate too. So saying the risk of severe weather events is rising but it's hard to attribute any given event is a very technical answer that is of no practical use. And the consequences of climate change extend far beyond extreme weather, something this analogy does not address.
Let's jump into a world of hypothetical experiments, and make two nearly identical universes, one where the baseball player does take steroids and one where he does not. Let's say we can observe the two cases side by side playing in what starts as an identical game - they each get the same pitches while they're up to bat. And what we see is that the steroid-taking player swings at different types of pitches than the non-steroid one. In other words, they react differently to their environment and so they swing at different pitches. [There might even be some real research out there on this type of thing... anyone have a reference?] And what's more, because the pitcher is going to pick up on this, he'll start changing the way he throws to each player. This shows that the two paths diverge fairly quickly. It also shows by analogy that technically, it's possible that every single weather extreme would not have happened without global warming, but that instead there would have been different weather extremes at different times and places, and quite possibly fewer in number. But who cares about this statistical issue?
And causality is not even the real issue behind the question - it's not something most people really care about (except for a few with academic interests).