Ubiq: you are right about breathing being part of a cycle, yet water usage is part of a cycle as well, which still doesn�t prevent these wise environmentalists from warning us not to consume too much water even in places with ample water supply.
And you�d be hard pressed to find an environmentalist that doesn�t believe exponential population growth is a problem, because no matter how much some may try to reduce emissions humans definetely add to the �carbon footprint� in the course of even modest living. We cook, travel, heat our homes, build these homes – in addition to producing all necessary items as well as comforts we desire. And this is all part of our task of living in and enjoying Hashem�s world.