CLIMATIC IMPLICATIONS OF AN 8000-YEAR HYDROGEN ISOTOPE TIME-SERIES FROM BRISTLECONE-PINE TREES

Tree rings from three dendrochronologically dated bristlecone pines we re analyzed for stable hydrogen isotopic composition. These trees give a continuous time series from 8000 years ago to the present that indi cates the presence of a postglacial climate optimum 6800 years ago and a continuous cooling since then. The qualitative agreement between th is record and records from other sources, such as ice cores, pollen, a nd treeline fluctuations, indicates that these climate changes were gl obal. This record can serve as a reference for other climate indicator s throughout the past 8000 years.