Everything is a threat to life on earth, it all goes back to the theory of survival of the fittest. As changes happen different animals will die off, and some will survive. This is how the world creates the strongest animals. since we are such a huge species of animal, and we have become so strong, this means that we have been adapting to the changes on the Earth so far, very well. I think that as the Earth keeps changing, we will keep adapting.