How long will life continue to exist on earth?

The earth has roughly 5 billion years left before the farthest limit of its life as a planet as far as we can project currently; that is roughly the time that the sun will expand into a red giant [it is not massive enough to become a supernova] and either totally destroy the earth physically, or at least render a hopelessly barren and burned out cinder. Well before that time, probably within the next one billion years, the slowly increasing temperature of the sun will cause the earth to grow hotter and hotter, and the earth will lose all of its water. If we have not managed to figure out a way to survive post-earth by then, it will be the complete end of earth-based human life.