Science fiction authors have dreams of the world's last days, and our distant descendants watching the sun flame out about four billion years from now. They're living in fantasy land. There's no way we're going to last even close to that long.
You see, the sun is getting hotter as it approaches flameout, and the earth is slowing down in its spin on its axis as tidal forces drag it down. As the earth's spin slows down, the cycle between day and night will become longer. A mere billion years from now the earth will stop spinning completely, and the light side will turn into smolding embers while the dark side will become a truly frozen wasteland. Long before that the day/night cycle will become so long that peak daytime temperature will surpass the boiling point of water, causing moisture to get into the upper atmosphere and get blown away by the solar wind, depleting the oceans while cooking all the water-based life forms during the day.
There is only one way to avoid this. We must force the earth's temperature down until the oceans freeze, thus stopping tidal forces and allowing the earth to continue with its current length of day/night cycle indefinitely and allowing us to live an extended, if slightly chilly, existence. Anyone opposed to this plan is engaged in strictly short term thinking.