abstract:Ecological collapse refers to a situation where an ecosystem suffers a drastic, possibly permanent, reduction in carrying capacity for all organisms, often resulting in mass extinction. Usually, an ecological collapse is precipitated by a disastrous event occurring on a short time scale.
To be sure you are marking a fundamental change in human society borders on the impossible--such events happen just a few times a century, and (barring things like ecologicalcollapse) rarely with anyone's ability to see at the time that anything has changed.