Sometime in the past, I wondered here if environmental books couldn't work with environmental settings instead of environmental themes. I'm not certain what environmental themes are. "We must save the planet?" "Humanity is destroying the Earth?" "We must save the planet from us?" If so, they are themes that are often used in cliched and very preachy ways.
Books with environmental settings or, maybe, situations, can have nonenvironmental themes, giving a book more complexity and getting away from heavy-handed lessons and warnings. A good example of this is Kissing Frogs by Alisha Seviny, which is a romance set on a trip to work with endangered frogs. The theme here could be described as the rogue outsider finding love with an opposite, which does not have anything to do with the environment. The setting--the work with the endangered frogs--provides the environmental aspect to the story.
Another example is Blight by Alexandra Duncan, a traditional dystopian, post-apocalyptic story set within a world in which only a few types of food plants are viable, because of a...you guessed it...blight. Agribusiness is the bad guy here, as business often is the bad guy in post-apocalyptic worlds. There's not a lot of dwelling on what happened, what brought humanity to this state, though. AgriStar is the bad guy not because it caused the blight (Though it may have. I'm embarrassed to say I don't remember.), but because of what it's done since the blight.
We've got a plot driven adventure here, including a journey story. We've got rebels. We've got evil junkers, a group of seriously bad guys who also appear in The Girl With All the Powers and The Boy on the Bridge. There are junker-like characters in the Rot & Ruin books. They may be a staple of post-apocalyptic stories.
My point is, this is the kind of narrative that could exist in many post-apocalyptic settings...a zombie apocalypse, an alien apocalypse...or in a religious dystopia. Blight is set in an environmental situation, but because it's more interested in its plot-driven adventure, it's far less environmentally cliched and heavy-handed than many books that might be described as environmental.