Why should I, as a Catholic, look after God’s creations?
Catholic Ethical Principle
Reverence for creation
“Ethical Principles” – Good moral teachings. i.e. what we should do.
How should we treat the environment?
We fulfil God’s commission with regard to creation when we care for the earth, with its biological laws, its variety of species, its natural beauty, and its dwindling resources, as a living space and preserve it, so that future generations also can live well on earth. 
In the book of GENESIS, God says, “Be fruitful and multiply, and fill the earth and subdue it; and have dominion over the fish of the sea and over the birds of the air and over every living thing that moves upon the earth” (Gen 1:28). Having “dominion over the earth” does not mean having an absolute right to dispose arbitrarily of animate and inanimate nature, animals and plants. Because man is created in God’s image, he should care for God’s creation as a shepherd and steward. For the first book of the Bible also says, “The Lord God took the man and put him in the garden of Eden to till it and keep it” (Gen 2:15).