A 13,000-YEAR CLIMATE RECORD FROM WESTERN TIBET

ALTHOUGH the Tibetan plateau is important in influencing the atmospheric circulation of the Northern Hemisphere 1-3, there are only a few continuous palaeoclimate records available, and these are limited to the plateau's northeastern margin 4-6. Here we present a 13,000-yr record from Sumxi Co (western Tibet), constructed from both lake-core and shoreline studies, which shows that conditions in the early-middle Holocene were warmer and wetter than at present. These results confirm model predictions of an intensified monsoon over the region at approximately 9,000 yr BP, owing to an orbitally induced increase in summer insolation 7,8. We also find evidence for warm, humid pulses at approximately 12,500 and approximately 10,000 yr BP, in phase with the steps of the last deglaciation, and for a. return to cold, dry conditions at approximately 11-10,000 yr BP, none of which can be explained by orbital variations. The existence of the cold episode confirms that the cooling associated with the Younger Dryas event occurred in continental China 6,9, and provides further evidence of the global nature of this event 10.