Everyone takes pause at 40. It's the age you have to assess everything in your life. It's the fictitious marker that's always coming up when you're young. The world really does look at you to kind of have it together by 40, and be successful by 40. Whatever success means.
A signal is comprehended if it serves to make us notice the object or situation it bespeaks. A symbol is understood when we conceive the idea it presents.
And given that there's been probably a ten-fold amount of information about terrorism through the media than there has about climate change; I think that's quite an interesting statistic.