Despite the Bible's affirmations of the goodness and renewal of God's creation, Christians get a bit ambivalent about Earth Day. We want to give thanks and we want to live up to our responsibility for tending what God has given, but get close to Earth Day and pretty soon you're hearing stuff about "Gaia" and nature romanticism and all kinds of over the top stuff that is weird and, frankly, "religious" in the least appealing sense.
But I'm happy to say that one of my parishioners has co-authored Narnia and the Fields of Arbol, The Environmental Vision of C.S. Lewis. It is an interesting exploration of Lewis' well known Christian works, along with personal letters and other material that show his immersion in the natural world and some common themes with environmentally concerned writers of the same period.
David O'Hara is a Professor of Greek and Philosophy at Augustana College here in Sioux Falls, and badly damaged because I often grab him instead of a reference book when I have a question about New Testament Greek. So have a heart. Check out the book.
UPDATE: see the comments below and also thanks to Karen Boyle for these good links.