I think you missed my point (see my other reply). Our impact has had a geological impact on the world going back thousands of years. We've had a very high profile role in the environment of the world. But a lot of the evidence of that role has not been extremely obvious (we don't have an uninhabited control planet to compare with so we have to make guesses, many of which have been wrong), and only recently have we come to figure out how massive the impact of humans on the environment has been for a very long time.

Looking back at, say, the bronze age, it takes a lot of research to figure out the extent of that impact. Looking at today it's blindingly obvious. But that doesn't mean that our impact has been extensive only recently, it only means that it's become blindingly obvious recently.