One that dates back to 1628 BC, 4700 BC, 7800 BC, 10900 BC (3100 y period)
Which are respectively 1) the exodus and sartonini eruption, 2) the black sea flood and a period of rapid cooling, 3) a period of volcanism and postulated impact, and 4) a confirmed impact that possibly triggered the young dryas cooling.
Following this, the next date would have been in 1500 or we assume the period is not exactly 3100 years but a little longer. Following backwards the former date was in 14000 BC (when a global extinction and climatic change began).
Or 1628 BC, 5400 BC and back to 9200 BC (3800 y period)
Respectively Sartonini, black sea flood and end of young dryas
Following this, the next date is due to around 2200! Following backwards the former date was in 13000 BC (when a global extinction and climatic change began).
If we assume the dates of 2200 BC, 6000 BC, 9800 BC and 13600 BC, the data seems more in concordance with the geological evidence. But that would once again would have given the next event at 1600 AC. If we assume 1800 BC, 5600 BC, 9400 BC and 13400 BC, then the next date would be at around 2000 AC, i.e. now! (3800 year period)
Or assuming a cycle of 3650 years, we may arrive at the final dates of 2012, 1638 BC, 5288 BC, 8938 BC and 12588 BC.
It is very likely that the climatic and geological disruptions that occurred between 1600 and 2200 BC may point to the same event. Since the dates of 5600 BC and 9400 BC point very accurately to the black sea deluge and end of young dryas climatic disruption. We should confortably assume an error in dating those years of about 100 years.
The other dates back to 536AC, 3123BC, 6400 BC and 9700 BC (3300 y period)
Which are respectively 1) a confirmed holecene impact, 2) a period of significan volcanism and postulated impacts, and 3) the end of the young dryas ice age period with abrupt rapid warming.
Following backwards the former date was 13000 BC. The next date is not until due 3500-3800.
One cycle of ~5125 years is found:
3123 BC, 8200 BC, 13330 BC (but apparently there is not so much evidence)
But looking at the 3800 year cycle and assuming some natural orbital variation, we observe that the neat worldwide disruption is set to occur between now and 2200.