Genesis 1: 26, 28 Then God said, "Let us make man in our image, in our likeness, and let them rule over the fish of the sea and the birds of the air, over the livestock, over all the earth, and over all the creatures that move along the ground." . . . God blessed them, and God said to them, "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."
God gave human beings the rule or dominion over the rest of His creation. This means we are stewards of His creation. This does not mean we can use and abuse the creation as we wish. We humans have ruined the good and beautiful creation that God has made and have failed to be good stewards. Christians often long too much for heaven and hence are indifferent toward what happens to the creation. But God has given us the responsibility of taking care of HIS creation. Therefore, we Christians should be the more serious environmentalists and conservationists. We may not go about carrying placards and protesting but we should at the least do what we can in our own little ways to help protect the beautiful creation that God has given under our care; for example, avoiding the use of polythene bags as much as possible even though the government might not have banned their use, being frugal with the use of water, not littering everywhere, not disposing our waste in the river, etc. You can think of other ways—big or small—in which you can help preserve the beautiful creation God has given us and hence become as good a steward as possible.
May God help us to be good stewards and caretakers to preserve the beautiful creation with which He has blessed us!