There have been 5 mass extinctions in the history of the earth. The most famous is the one that wiped out the dinosaurs, but that was not the worst of them. I have been trying to look up the exact figure on how much of life was left after the worst of them--my memory says 10% but my internet is hating me right now.

My point is that life has taken heavy blows in the past--we all know about the abrupt end to the dinosaurs (not just them but plant and sea life died as well). While one change can harm an individual ecosystem very much, given time, life will most certainly find a new niche and flourish. It is terrible to hear about one species or another being lost forever because of humanity's stupidity. But it is very comforting to me to know that life does have a very long, battlescared history. I doubt we could change that even by nuking the entire planet. Life is a tenacious, beautiful thing.