The edge of extinction is not just a metaphor; system collapse is not a thriller. Ask any refugee of any species
Plays at the ignorance of people. Its been that our society tends to take things lightly if not entertaining or dramatized. It's not a metaphor and it's not a thriller really points to the tiredness of the author to people who don't realize that this is bigger and more than entertainment. Continuously stating that it not only afffects humans but "critters" too.