A spectacular 10‰ drop in the 18O16O ratio (δ) in precipitation indicative of rapid cooling occurred at Camp Century, Greenland, 89,500 y.a. The timing is based upon an assumption of δ periodicity being constant in time. Onset of the Wisconsin pleniglacial is reflected by 6‰ δ drop at 73,000 BP. Similar event might have occurred 109,000 y.a., but the core at corresponding depth is missing. Could it also happen today?