They've named the ages of the Holocene after critical climatic events 4.2k, 8.3k, and 11.7k years ago. In other words 4.2k, 4.1k and 3.4k years apart. Looking at that series it's easy to wonder if we're overdue for another one.
I suppose it still counts if it's self inflicted.
Yeah, from what I can tell from chatter online, the anthropocene has been reported on and is assumed to be true, but has not been given an official designation yet.