This should be obvious. There is some good news in that the human population is plateauing, and is projected to gradually decline, as a result of urbanization, educated women, mass entertainment, secularism, and other influences.

If we want a natural world around us, we have to leave a lot of it natural. Sometimes it reminds us that's not really an option, but a requirement for survival. One thing we will learn from space colonies is that humans cannot thrive in a monoculture surrounded by sterility.