How long do you think our planet will tolerate our carelessness until it kills off all the humans?

I mean, there are oil spills, and earthquakes and volcanoe eruptions and wars and drought and famine... Do you really think that life as we know it will last another 50 or 100 years? I am not sure if Life remains to be somewhat stable in another 30 or 40 years I will be suprised. What do you think??