A very nice science book, though a little old by now, is The World Without Us by Alan Weisman. It is a complete thought experiment with no bearing on any real situation saving perhaps The Second Coming If You Wanna Believe That (I don't), asking what would happen to the rest of the planet if human beings just dissapeared? Not massively died, leaving our bodies to contribute carbon and nitrogen, not blew each other up, leaving nuclear fallout or just blasted landscapes...just went away. Poof. Of course that's not going to happen (see my above note about second coming), the book is interesting to me anyway becasue of its rich reseach into ecology and evolutionary biology. It does a nice little story about how we got here and to be the way we are, and how our effects have changed things, thus how things might go on changing based on what we know if we weren't here to contribute to it.
There is an important environmental message in this book, which, thankfully, is not "oh humans are so terrible look at how we've destroyed the planet wouldn't it be better off if we just left/went back to our primitive non-technological ways."
The book reminds us that we are nature, we are a species that evolved, lived, and adapted to the predators and prey who existed with us, that developed a successful set of traits for overcoming the evolutionary checks put on us by our predators and our prey, spread out of the land of our birth, and adapted ourselves to occupy pretty much the entire world. In short, a species doing what species do. We possess a damn successful set of traits allowing us to vary our diet and our tolerance of climate to encompass pretty much the whole planet--and the forces of evolution shaped us into what we are just as much as it shaped all the other species that exist with us right now. And all the environmental destruction, all of the simple change we have caused from plastic pellets in the ocean and mass extinction of other mega-fauna to our cities and towns and agricultural systems, are a product of our nature, and we are a product of nature in it's larger form. If it hadn't been us that had outsmarted the predatory checks and perfected our ability to prey on animals and learned how to manipulate the life cycle of plants to our will--maybe it would have been a different species, using whatever adaptations it had to succeed in spite of competition, and succeed on whatever terms those adaptations let it succeed. Humans are NOT the only species who, when unchecked, create environmental destruction. Since nature is very much full of inter-species competition, what we have done is not evil and callous and just as on so terrible violation of the natural world. It's not against nature at all!
In fact, what we have done has allowed us to occupy a unique position on this planet: able to recognize and contemplate our effects on other species. Recognize that we both compete directly with other species for space and right to live, but also depend on what other species to do make our lives have quality. With our needs met (this is arguable when considering all 9 billion of us), we can contemplate the needs of others, and how those needs correspond with our own, and even, sometimes, how they don't but that us living still affects them. We can make the choice to preserve endangered species that benefit us, or, more powerfully, to preserve the ones that don't really do a damn thing for us but we still have this idea that it is the right thing to do. Ideas about right and wrong come from our history as a social species, but that doesn't mean that the meaning of right and wrong do not exist just because they are of our own construction. We are in a way overcoming our nature, transcending it, to extend compassion for the sake of it to places where nature did not expressly place it to begin with. We had to follow nature to get here. But now that we are here, we have the ability to do something about it.
To me, that's environmentalism. First, protecting the things that protect you, like air, waterways, and topsoil, like species that are useful because of biological adaptations that we don't have but benefit from: latex trees, rumen stomachs, working forests that take dirt out of air and water through natural filtration and protect against soil erosion besides. But also, philosophically, because we have transformed our world to suit our needs and so now have the ability to afford to be ethical: because we recognize that our actions have consequences for others, others being not necessarily members of the human species. Caring enough to maybe try to redefine needs as wants, and try to do a little less harm. We are damn special because we can care about harm, because the nature of surviving usually doesn't allow it.
And that's bleeding-heart liberalism if anything ever was.