Maverick Philosopher doesn't celebrate anything as politically correct as Earth Day. Maverick Philosopher celebrates critical thinking. So I refer you to William Cronon's The Trouble with Wilderness; or, Getting Back to the Wrong Nature. A rich and subtle essay. Excerpt:
Many environmentalists who reject traditional notions of the Godhead and who regard themselves as agnostics or even atheists nonetheless express feelings tantamount to religious awe when in the presence of wilderness—a fact that testifies to the success of the romantic project. Those who have no difficulty seeing God as the expression of our human dreams and desires nonetheless have trouble recognizing that in a secular age Nature can offer precisely the same sort of mirror.
To put (roughly the same) point with Maverickian aphoristic pithiness: Nature for the idolaters of the earth is just as much an unconscious anthropomorphic projection as the God of the Feuerbachians.
Thus it is that wilderness serves as the unexamined foundation on which so many of the quasi-religious values of modern environmentalism rest. The critique of modernity that is one of environmentalism’s most important contributions to the moral and political discourse of our time more often than not appeals, explicitly or implicitly, to wilderness as the standard against which to measure the failings of our human world. Wilderness is the natural, unfallen antithesis of an unnatural civilization that has lost its soul. It is a place of freedom in which we can recover the true selves we have lost to the corrupting influences of our artificial lives. Most of all, it is the ultimate landscape of authenticity. Combining the sacred grandeur of the sublime with the primitive simplicity of the frontier, it is the place where we can see the world as it really is, and so know ourselves as we really are—or ought to be.
Related: Timothy Treadwell and Nature Idolatry. (Treadwell was the romantic fool who camped without protection among grizzlies in Alaska, thought it acceptable to end up bear scat, and did, along with his girl friend.)