Although it is very difficult to define morality, I don't think it makes it any less significant. It is clearly very useful, and makes most people happy. I think morality has something to do with responsibility to a collective, arising from the realization that the individual is interdependent with its surroundings, and therefore the interactions involve compromise to ensure the survival of both individual and surroundings, without which neither will survive - although the argument that our environment doesn't need us to survive XD is fine and dandy as it is.
I think morality can dig real deep into our psychology and culture, and we can learn from the introspection of our own morality about how we feel about relationships, responsibility and commitments. We can tap into concepts like courtesy, respect, and honour to describe our emotional motivations for protecting the environment. And while satisfying your personal needs of courtesy, respect, and honour sounds pretty selfish - it's not as bad as it sounds Just as long as it goes both ways instead of in one direction. And I think that is also the liberal viewpoint of the world - one that we can all relate to, living in liberal democracies.
So. Protecting the environment can have a moral basis stemming from the recognition that humanity is interdependent with it, and the relationship is two way for both - i mean humanity - to survive. Everything else is a detail. Whether or not polar bears are worth saving depends on a good study of ecology - they really might not be worth saving, but it's important to find out whether or not they are first. And because these ideas of environmental protection resonate within our societies, there is no reason not to.