I was talking to someone recently who told me that scientists have postulated that humanity would have (in the long term) a tangible effect on the earth even if we went extinct today. Possibly starting around the time of the Agricultural Revolution. We killed off enough megafauna that we affected methane levels heavily, and apparently that and some other things would show up in a core sample now. Short conversation, didn't get details. Thought it was interesting though...
This was one of the sadder reads as of late. The monarch butterfly migratory path goes directly through my universities campus. It's one of my favorite days of the year when I wake up, go outside, and there's thousands of butterflies going around.
I wish I could say to that. From now on it does since that's clever. Also, I see you're from Upstate NY! Whereabouts, if I may ask? That's where I'm from too. They're plentiful in parts of Rochester.
Upstate represent! Edit: I see I didn't actually answer your question. I'm from Broadalbin, a small town of 5000 not very close to Rochester.
Yeah, also if humans disappeared right now, it would take hundreds (thousands?) of years for CO2 levels to stabilize to pre-industrial revolution levels. Sad to hear about the butterflies though, I've definitely noticed an absence of them in my area (upstate NY) in recent years.