GLACIAL-INTERGLACIAL CHANGES IN MOISTURE SOURCES FOR GREENLAND - INFLUENCES ON THE ICE CORE RECORD OF CLIMATE

Large, abrupt shifts in the O-18/O-16 ratio found in Greenland ice mus t reflect real features of the climate system variability. These isoto pic shifts can be viewed as a result of air temperature fluctuations, but determination of the cause of the changes-the most crucial issue f or future climate concerns-requires a detailed understanding of the co ntrols on isotopes in precipitation. Results from general circulation model experiments suggest that the sources of Greenland precipitation varied with different climate states, allowing dynamic atmospheric mec hanisms for influencing the ice core isotope shifts.