There are many ways the world can end:

1. Solar Flare

2. Major Eartquake

3. World Wide Tsunami / Flooding

4. Nuclear War or Nuclear Meltdown

5. Huge Terrorist Attack

6. Major Marshal Law

7. Rapid increase of Prices / Economic Calapse

8. Global Pandemic (Spread of Unknown Disease with unknown cure)

9. Oil Crisis

10. Shutdown of Power Grid

If there are other possible ways (logical ones) in how the world could end, commit & tell now.