There's quite a difference between an unmonitored event and shooting oneself in the foot. We're a technologically capable, conscious, foreseeing species; things having happened back when we were not are not an excuse to behave today as mere beholders, or worse, as levers of the system instability.
A little knowledge can be a dangerous thing. We have some technology, we have some understanding of how our biosphere works and we have some ability to effect change in our environment. The earth is a big, complicated machine- are you confident that we can predict the long term outcome of our actions when we try to "fix" things?
