"A Pail of Air" (Fritz Leiber) + "Out In The Country" (Three Dog Night)
There is a Fritz Leiber story entitled "A Pail of Air", a story that despite its hopeful ending always strikes me as spectacularly bleak. In it, Earth has been ripped out of the solar system by a wandering black hole, and story is set in the aftermath, where the average temperature of the Earth is the Universe's average temperature of 3K. The atmosphere of Earth has frozen out.
The story centers on one family scratching out a precarious existence in the face of global, complete, utter catastrophe by keeping a fire going. (As it turns out, the atmosphere freezes by gas, so the ground actually has highly refined sources of oxygen, nitrogen, carbon dioxide, etc. in it, so getting oxygen is as easy as going outside and scooping it up... if you can deal with the temperature of the gas, that is.) Two children in the story have been raised in this world.