And this harms the planet how? There are planets in our galaxy that have no life what so ever, and they are doing perfectly fine as planets. A planet is still a planet regardless if it holds life.
Events in the past have had much more serious impacts on the status of life on Earth than all of humanity's acts combined.
The meteor shower that brought about the Ice Age(a natural event, mind you) completely transformed the surface of the planet and exterminated the majority of its lifeforms.
Humans aren't very destructive compared to the other forces that exist. Its that we are conscious, that makes what we do so much more grave compared to everything else thats out there, apparently. At least to those who wish to portray humanity in such a dramatic light. We are so important to the nature of things that we control the power to bring about the very end of all thats around us. Its all masturbation of the human ego.
We are an ego-centric species and are bold enough to say that we are worse than the harshest forms of destructive inanimate events that occur merely by chance of physics and the right timing. When nothing we have done thus far in our existence as a species amounts to the acts of destruction that occur with planets, super novas, black holes, and all other forms of space matter interacting with each other simply based off of timing and cosmic chain reactions.
We are the largest threat to our own survival and that is the bottom line of the matter. That is basically as unique as we are compared to other species on this planet.