What is the most harmful thing you could personally do to the Earth and/or human society?

Everyone talks about how they want to make the Earth a better place, but what would you do if you wanted to make life on Earth worse in the future (for humans and/or animals)? I am talking about you personally, so don't give an answer like "spread a bioweapon" or "detonate a nuke" unless you personally have the knowledge to do such a thing. Someone might say sell everything they own and burn the resulting pile of money, but this would actually result in zero effect because the remaining currency still in circulation would just become more valuable. Likewise, killing others simply alleviates the overpopulation problem or has negligible long-term societal impact (unless you know how to fly a plane). The most destructive thing that came to my mind is to burn my own house down (which is legal, although I'm not necessarily looking for legal answers). What about you? I am betting that the large majority of people are pretty impotent in accomplishing real good or real harm, unless they happen to be a special forces commando or President or something. Do you have any real power that could impact the globe, or are you just a pawn?