STABLE WATER ISOTOPE BEHAVIOR DURING THE LAST GLACIAL MAXIMUM - A GENERAL-CIRCULATION MODEL ANALYSIS

Global water isotope geochemistry during the last glacial maximum (LGM ) is simulated with an 8 degrees x 10 degrees atmospheric general circ ulation model (GCM). The simulation results suggest that the ''spatial '' delta(18)O/temperature relationships observed for the present-day a nd LGM climates are very similar. Furthermore, the temporal delta(18)O /temperature relationship is similar to the present-day spatial relati onship in regions for which the LGM/present-day temperature change is significant. This helps justify the standard practice of applying the latter to the interpretation of paleodata, despite the possible influe nce of other factors, such as changes in the evaporative sources of pr ecipitation or in the seasonality of precipitation. The model suggests , for example, that temperature shifts inferred from ice core data may differ from the true shifts by only about 30%.