Last Chance to See (1990) Douglas Adams and zoologist Mark Carwardine traveled the world visiting endangered species - kakapo in New Zealand, mountain gorillas in Zaire, Yangtze river dolphin in China, Komodo dragons, aye-ayes in Madagascar, northern white rhinos.
This is Douglas's humor applied to real extinction. The absurdity is still there - incompetent bureaucrats, human ridiculousness, travel disasters - but the stakes are actual animals disappearing, not fictional planets. You're laughing at the journey while facing genuine loss.
Douglas loved this book and often said it was the book of which he was most proud. He got to combine his comedic voice with something that mattered deeply to him. The species are going extinct mostly through bureaucratic indifference and habitat destruction - Vogons building bypasses, essentially. But these animals can't be rebooted. Once the baiji is gone, it's gone. No Magrathea for river dolphins.
As always with Douglas the tone is tot preachy or despairing. It is observational, funny, genuinely moved by what he is witnessing. He shows you the weirdness and wonder of these creatures - the kakapo that tries to mate with Mark Carwardine's head - while making clear we're losing something irreplaceable.
I also think that his description of how Rhinos experience their world , their umwelt in a smell scape which shapes their experience of time and what to pay attention to is a brilliant example of his genius for engaging with perspective.
For your students: It's humorous eschatology applied to the real world. Same toolkit - absurdity, companionship, clear-sightedness - but now the apocalypse is actually happening, one species at a time. And you can't rebuild them.