The problem is knowing the tipping point or the point of diminishing returns. The Earth has never faced a challenge like we are experiencing today. This doesn't mean that the Earth hasn't faced its share of challenges: Snowball Earth, multiple extinctions etc. and each time it rebounded. Different than before. but recovered nonetheless.
The difference being humans weren't around in these prior incidences. In all previous situations "Nature" was able to correct itself and move forward in ways that conformed to natural laws and evolutionary principles. The Earth will no doubt eventually correct itself according to these same principles. The only question that remains is, "At what point do we reach the point of diminishing returns where the Earth is incapable of stopping the present climate change trend, forcing the Earth to move to unto its next iteration?"