A PREVIOUSLY UNRECOGNIZED LATE-GLACIAL COLD EVENT IN EASTERN NORTH-AMERICA

THE transition between the last glacial period and the present interglacial was marked by pronounced and abrupt changes in climate1,2, one of which, the Younger Dryas event, resulted in a return to almost full-glacial conditions. Here we present evidence for a short but intense cold period in eastern North America, pre-dating the Younger Dryas, revealed by analysing the organic, pollen and midge content of lake sediments at very high resolution. We name this event the Killarney Oscillation and it lasted from 11,160 to 10,910 radiocarbon years BP. Because this corresponds to the Gerzensee Oscillation in Switzerland and can be correlated with other short-term events reported from across the North Atlantic seaboard3-14, we conclude that a single event affected all of the North Atlantic region. This pre-Younger Dryas cold period is similar in nature and geographic extent to the major cooling of the Younger Dryas15, raising the possibility that these two events are causally related.