Lots of people believe the world is going to end, and lots of that can be blamed on good fiction. A good story can instill fear in an entire population. Once upon a time, back when the TV didn't exist, a nationwide panic was created over a radio program. The public literally believed that Earth had been invaded by an alien population. That is good writing. The end of the world can make for a great topic -- just ask the Mayans. We're still talking about them 2,000 years later. A good story is pretty powerful stuff.
The End of the World as They Know It
Writing about a catastrophic, world-ending event can be a heady experience. You can make it thrilling, you can make it sad, you can make it frightening and horrifying. That's the power of the pen: you can do anything you want. But some writers take even that a little too far. Because you can't just end a world out of nowhere. You've got to lead up to it, a little.
Before you can end your fictional world with some sort of catastrophic event, you have to make me care. You can't just end an entire world without making it an emotional experience. Should I be glad this world is ending? Maybe it's a horrible place filled with villains. Should I be sad? Was there a hero or heroine I just can't help but love, someone who must now die along with all the rest? Should I be frightened and horrified? Maybe your world ends in a way that could make my world end, and maybe that scares me. Let me get to know the world before it ends, and meet some of the people who live on it. Otherwise, I'm going to be yawning over your descriptive passages and rolling my eyes as lifeless body after lifeless body is consumed by lava (or whatever).
To make the end of the world matter, you've got to add the human connection. And put some structures or natural wonders on the world while you're at it. I'm going to feel the loss of a beautiful world more keenly than an ugly one.
And when you finally end the world, or write about your catastrophic event, do it spectacularly. Describe the screams, the smells, the pure horror of the event. After all, the end of the world isn't something that happens every day.