You're not wrong. I'm expecting a long slide. Future historians (if we make it through) will probably have a date they consider the tipping point, much the way we point at the assassination of Duke Ferdinand at the trigger for WWI.

And if we don't make it through, we'll know (right at the end there) that this is probably why we never found extraterrestrial radio signals - poisoning your own world has got to be one of the Great Filters. Cheery thought, right?