You've been warned.

I'd like to thank our university, not only for preparing us for any contingency - such as a return to the 1950s and a need for air raid sirens... but also for rolling it into one easy to handle concept: disaster. 

Now I know that if I hear those sirens again, while the nature of the disaster may be varied and veiled, the basic facts are clear: disaster is upon us, please keep calm.