Don't we still have burning coal mines underground? Won't the earth collapse into any dead space that occurs? We just don't always know when or what will happen or whether it will harm something or not. It's only in this way that we learn to predict the consequences of any future actions. Of course any such future consequences end up in that day's political arena. We're already finding out some of the negative effects of our "clean energy" efforts as we move that to above ground resources that consume a lot of space.