Rather than blaming the individuals, you must blame the government. Among the adults in any particular country, you will find some people supporting the measures to save the planet, and some others who are opposing it. The government should properly educate the citizens, and then implement strong measures meant to preserve our planet for the future generations.
There are ways to reverse the flow of nature and that is to detonate all volcanoes in the world and the world will cool down within a day. When the gases from the volcano will spread all over the atmosphere the green gases will be gone and the earth can no longer trap the heat coming from the sun. When this happens the earth will cool down and we will face ice age once again.
Not everything depends on the person. There is also solar activity and activity of other planets. A man does a lot of harm to the earth, but killing all people does not make sense.
I just want to make this thing clear, earth damage, is a broad phrase, the planet is also damaged by natural phenomenon such as earthquakes, typhoons etc. not just us humans.
And haven't you had the thought that in 'Stone Age', all the things that surrounds us, we don't have even a spec of idea what are these? My point is if you are really pinpointing that the 'humans' are mainly the cause of destroying this planet, if the people back then are as smart as we are today, then we probably have prevented this to happen and eventually stick in the 'natural way of life'.
Yes we are destroying it, and for what? For the future, through science we have come to understand and realize the secrets of this planet though, there are still things we do not know. And by this, we have discovered various technologies and invent new creations. If we didn't do what we did, we probably wouldn't evolved and we probably wouldn't built civilizations.
This planet is not in the good shape anymore and at the moment we do not have the technology to help the earth.