The world? Our planet will continue to orbit the sun until it goes supernova in a few billion years, so we won't worry about that. Our encrustation on the planet's surface, however, is a different matter. Impacts from asteroids could end us in a trice, we could pollute ourselves out of existence, then there is always full scale nuclear war if you want something to keep you awake at night. Could any of these things happen tomorrow, possibly. Will worrying about it today help, definitely not. Our best bet is to try and make our little corner of the world a better place-at least leave it better off than we found it.