From the top: In an article in GSA Today (Feb. 2009), newsletter of the Geological Society of America, 21 scientists discuss evidence for international formalization of the designation of the Anthropocene epoch, as the current interval of anthropogenic global environmental change; i.e., environmental change induced by human action which has global implications. The Anthropocene, they suggest, began around AD 1800, succeeding the Holocene. The scientists are formalizing the reality that we inhabit a human-controlled (or at least overwhelmingly human-impacted) world. The whole Planet has been humanized.
My point: Humans are changing the face of the Earth, its species, even its chemistry to the point that our actions are paramount.
To the bottom: Every day we make small decisions that impact the physical world, both local and global, usually without feeling we are interfering with "Nature." Humans are the controllers now. We decide. It's our Planet to alter in the ways we collectively decide.
It is all altered already. But, will we continue to alter the world in ways that ensure our survival? If not, then a possible remnant of humanity left over after the all-systems crash might label the next epoch the Necrocene: the Death Epoch.