[Red Badger]

The enviros I know are stupefied when I say, “In the end, our Sun will become a Red Giant and everything on this planet will be burned to nothing. Plants, animals, humans, oceans, moon, everything will be gone. So no matter what you do, eventually it will all be gone in an instant”...........

[RightWhale]

Long before that the oceans will boil off. Possibly the planet itself will be vaporized. Global Flash Vaporization.

[Calvin Locke]

One scientist proposed removing mass from our star to make it last longer.

But then there's the cycle of mass extinction every 65M years, so any thing beyond the concept may be moot.

And there's always the possibility of a Shoemaker-Levy 9, or an Apophis ruining some people's day.

I suppose we, er, the Earth can be swallowed by a black hole, or not survive a galactic collision.

And let's not forget a massive GRB from a "close" supernova...