Many years ago I read this short story:

(Most of) humanity lives in tanks/machines that feed them. They have a rich social life. They hardly remember/realise this is not the 'real' life.
The main character (living in a tank) experiences strange failures and disturbances. Slowly he realises that something in the 'real world' is causing trouble. In the end he opens up his tank and climbs out.(that is amazing; because he hardly has any muscles left).
It appears that a group of humans (that are not living in the tanks) are opening the tanks to 'free' the people inside. This is because a new Ice Age has arrived and glaciers threaten the caves the tanks are in.
However: the main character has lived way too long in the tanks and is physically too weak to be rescued. The main character crawls to the opening of the cave and finally sees the real world again: a dark night with stars and glaciers approaching.
There he (peacefully) dies.

Any idea of the title and/or wiriter? I read it in Dutch; and I am not sure if I choose the right words to describe the plot...