atmospheric science - Is the butterfly effect real?

Is the butterfly effect real? It is a well known statement that a butterfly can, by flapping her wings in a slightly different way, cause a hurricane somewhere else in the world that wouldn't occur if the butterfly dídn't move her wings in a slightly different way.

I can't imagine that this is true.

Answer

First the statement is a poetical way to express how in chaotic systems, small changes can trigger drastically different results. This statement does not attempt to relate butterfly movement to large scale weather changes.

I would say we have elements to say it is not, for example, waves are a chaotic behaviour of the sea surface, but we have never found tsunamis born out of this; you can always trace a tsunami back to certain earthquake or similar large scale event. You can think of a number of chaotic systems and we have not been able to link their behaviour with larger scales effects.

Finally, if small changes in systems could trigger large scale changes, our science would look very much like witchcraft, because we would have to admit that sudden large events can appear without apparent cause, at least until we found the small butterfly pattern causing them. But even tornados, which are hard to predict, are known to be preceded by large changes in atmosphere pressure and other large scales features.