If you want ecology apocalypse, check out John Brunner's _The Sheep Look Up_ (written in the early 70s). No other book I've read scared me as much as that one. I think what did it was the utter normalcy with which everything was just accepted as is.
It's a great book, unfortunately few of its environmental predictions are very valid today. Brunner missed the greenhouse gas problem and focused on things like air quality, garbage, sonic booms (!), poisoned drinking water and overpopulation. One thing he does get right is the need to develop new agricultural tech -- a core subplot is about a company that uses a new hydroponics system to grow cassava at a large scale, for distribution to impoverished third-world countries.
The real impact, for me, was twofold: First, the idea that someone could develop a simulation of modern society to the point where it could make a recommendation about how to make a course correction (which turns out to provide the books its deliciously tragicomic ending), and second, the idea that society's collapse will prevent a technological solution to envionmental disaster. The latter is implied rather than spelled out.
