In my eyes there are only a few ways Life as we know it could end. Global war(or nuclear war), Significant Super volcano eruption, Global disease
outbreak, an ice age(brought on by nuclear war, supervolcano, or meteorite) lastly large meteorite... I don't think any of these are predictable with
in a year of their occurance really. As far as anyone in the past predicting said events, I really doubt it. We can make educated guesses, but they
aren't likely to accurately predict our demise. Most meteors that come close to the earth are discovered with in a few years of their approach, at
which point the really close calls aren't reported until after they pass. There are just so many of them, and in the darkness of space, they are
extremely hard to spot and predict.
There are too many links for Asteroids, but you can research it yourself. JPL does an alright job with providing Near miss, and potential impact
risks. They number in the many, and JPL admits many of them catch them by surprise.
NEO JPL
Global disease could happen anytime. Will we predict the end, I doubt it. Every now and then there is a scare with a potentially damning contagion but
it hasn't played out yet, and I really doubt we will predict exactly when it will happen. Likely while it's happening ha ha.
super volcano
Caldera
Super volcano eruption, well... It's hard to say we try to predict when these eruptions will take place but volcanoes do pretty much whatever they
want, when they want. We can sometimes catch seismic hints just before it happens, but it's not always as easy as some people think, and it doesn't
give us a whole hell of a lot of time to do anything. I mean considering most super volcanoes are right smack in the middle of societies they are
pretty much screwed for lack of a better word, and many of which are so large the eruption will have global consequences. Again, good luck predicting
a date. It could happen today, and what would we do?
Nuclear arsenal
As far as nuclear war, what with some 19,000 reported warheads worldwide it could happen any day. All it would take was one to really kick it off with
all the tension, grudges and fear we all hold so dear in our hearts. Seriously, make an accurate prediction for any of these and I will pay you all
the worlds gold. Keep in mind it will be useless given the world will end. So good luck, god speed, live your life to the fullest, any of these events
could happen with very little or no notice what so ever.