Trends and features of clintatic changes in the past 5000 years recorded by the Dunde ice core

A 81BO record from Dunde Ice Cap, located in the Qjlian mountains on the northeastern margin of the Tibetan Plateau, has been analyzed and interpreted. With an ice temperature of 7.3°C at a depth of 10 m and -4.7°C at the bottom of the ice cap, and an accumulation rate of400mma· l , the Dunde core has provided interesting results. The upper part of this core, core D-I, can be easily dated by a combination of 8IBO, microparticle concentration and conductivity. It can also be dated as far back as 4550 BP by counting dust layers in ice. Based on the time scale established by the above methods and on the 8lB Otemperature relation, the OIBO fluctuations in the upper 120 m of the core can be interpreted as mainly due to climatic changes during the past ~ 5000 years. The warmest periods in the past ~ 5000 years in the core were found to be cen tered on the presen t, 3000, and 4100 BP, and the cold er periods center around 500, 1200,4000, and 4500 BP. It is clear from the ice-core record that the Little Ice Age was only one of many cold periods in the past, although it was the cold est period in the past 500 years.