DECADAL CIMATIC VARIATIONS INDICATED BY DULAN TREE-RING AND COMPARISON WITH OTHER PROXY DATA IN CHINA OF THE LAST 2000 YEARS

摘要

Based on high-resolution tree-ring data from Dulan area of Qinghai Province, five spells have been divided: the warm period before 230's, i.e. "Medieval Warm Period", the cold period including the "Little Ice Age" 1420' between 810's A.D. and 1070's, i.e. "Medieval Warm Period", the cold period including the "Little Ice Age" 1420' s -1870' s and the warming period since 1880's. All the eleven coldest or warmest decades and several great abrupt changes took place before the Middle Ages, indicating that climatic system operated in great instability during the period 150's -1100's A.D..