In the novel, humans all lived underground and were decanted - not born, were undersized, short-lived, emotionally-empty, and prone to suicide and freak-outs. Above ground there were mechanized factory farms of mono-cultures with no native life remaining; a single robotic whale swam the oceans. In the denouement, a number of long voyage space ships returned to reseed the planet with a genetic library sent from far in the past.
I read it in the mid-1980s on the the heels of reading "Ecotopia" which seems to have eclipsed any memory of the title for this book. Any ideas?