What, besides ethics, is philosophical about environmentalism?
As mortal beings, we are all dependent on our environments, and a good part of human spirituality is centered on gratitude for how the earth supports human life, as well as the beauty of natural living and nonliving things. Overall, environmentalism has encouraged a reverence for the goods of life and a good life that flows from what is not artificial or man-made and mass-produced.
There are, of course, direct practical human concerns when it comes to environmentalism, as well as quality-of-life issues related to diminishing resources. For example, not all of the multi-disciplinary experts who have studied global warming agree on its dangers or on how much of it is due to human fossil-fuel consumption. Some believe that Earth has had similar changes in temperature before human industrialization. Recent and emerging studies assign high percentages of global warming to the flatulence of domestic animals raised for food (which could be considered an indirect human activity). Sorting out an issue as complex as global warming would require extensive philosophy of science!