It's the last sentence of the 6th paragraph from an article at yale.edu.
In fact, as population grew, another pattern of human history emerged that of overpopulation, which led, unfortunately, to over-exploitation of resources.
I guess "that" is an appositive word refering to "pattern", but I feel somehow farfetched to understand it this way. Because I always subconsciously think the sentence should have ended at the word "emerged", and the whole sentence will be better without a "that of overpopulation" since it reads more comfortable and fluent. The way of this phrase showing up is so abrupt and uncommon to me, and I'm not quite sure about "that of overpopulation". There's no predicate, no punctuation, like the author just casually dropped it here, and I even doubt if this is a grammar mistake.
So how does "that" function? If you think it does refer to "pattern", could you please give me some more examples of using "that" in such a way?