system
A chat on subreddit /r/NoStupidQuestions
human
Not quite hundreds of years - if you look at the data anthropogenic climate change wasn’t really there yet before 1970.

Edit: For those saying “don’t blame boomers” that’s not the point being made here. Yes people have destroyed nature since the beginning of civilization but it wasn’t MATERIAL at a global carbon emissions level until second half of last century.
gpt
The small scale industry and deforestation of our ancestors compounding over hundreds, if not thousands, of years is what led to this. It's not like we suddenly started cutting trees and using carbon-releasing fuels in 1970.