What nature says is something that encompasses all matter of life and matter rather than life that is naturally present on earth. In the purest sense, nature is an environment without human activity in the sense that there is no human intervention in forming it.
Nevertheless there is a really deep worry about climate change caused by anthropogenic releases of greenhouse gases, especially carbon dioxide, and their interactions with human and natural guidance. Therefore, although the natural occurrence without human intervention but human beings can damage this natural ecosystem. For that matter keep nature as much as we can.