I very much recommend William Ophuls, Ecology and the Politics of Scarcity (1977) and Plato's Revenge (2004). He delivers the essential message of Limits to Growth in a chapter (TL;DR: there are limits to growth, get used to it), and explores the rather more interesting elements of the political dynamics of this.
Yes, life on earth has existed. Actually, for closer to 4 billion years. For the first 3.5 billion of those, there was little more complex than a single-celled organism, and those managed to just about destory the place (Great Oxygenation Event, Snowball Earth). The cycle's been repeated a few times since.
Humans are accelerating that process greatly this go-round.
http://www.worldcat.org/title/ecology-and-the-politics-of-sc...
http://www.worldcat.org/title/platos-revenge-politics-in-the...
Biological life existed for 5 orders of magnitude longer than civilization without the sort of devastating consequence civilization has wrought.
The cut off is civilization suggesting that it is no more disruptive than biological life to the long term sustainability of itself, but that is just obviously not looking like the case right now. Exponential population growth in a resource-constrained system will hit a limit and the result will not be pretty.
That is far from scientifically certain. Out of the extremely numerous extinction events in Earth's history, 5 of them have been extremely major, and we are probably going through the 6th right now. Probably. It's still too early to make statements about this. Will the geological record of the age of humans be more pronounced than the other events? Probably, but we can't claim that wearing a scientist hat. It's even more dubious to claim that this 6th event will have a more strongly negative effect on biodiversity. Things are happening so fast, and once all is said and done, humans may ultimately increase the diversity of Earth-derived life, because we have the ability to recombine existing species and even bring back functional extinct ones. It all depends on how we manage from here on out.
First, define "devastating consequence" in clear terms. Then, and only then, go search the web for "oxygen catastrophe".
Does this answer your question? https://ecology2011tamara2011sp.files.wordpress.com/2011/05/...
I have to ask, what do you mean by sustainability here? Biological life has existed on earth for about 2 billion years, the human race for a million years and civilization for thousands of years. So in what sense is life on earth not sustainable, and what would have to change for you to consider it sustainable?
In the ultimate long run life anywhere isn't sustainable; the sun will eventually die and then the universe itself will experience heat death. So what's your cut off?