Lake Sediments as Continental δ18O Records from the Glacial/Post-Glacial Transition

As in polar ice, 18O variations of precipitation are recorded in carbonate sediments formed in lakes (lake marl). We have analyzed many late-glacial profiles from Europe, There are strong l8O variations which coincide with well-known pollen zone boundaries and which indicate that abrupt, drastic climatic changes occurred in the late glacial period. These events are a major warming around 13 ka BP (pollen zone boundary Oldest Dryas/Bölling) and a marked cold phase between about 10.8 and 10 ka BP (Younger Dryas). Comparison of the δ18O records of European lake sediments and of Greenland ice cores reveal a striking similarity which indicates that climatic changes in the late glacial and early postglacial were parallel in Greenland and in Europe. First results from North American lake-sediment profiles do not exhibit similar δ18O variations. This pattern of climatic changes was probably caused by retreating and readvancing polar water in the high-latitude North Atlantic Ocean, as discussed by Ruddiman and McIntyre (1981).