Abstract: Climate of a long-term history can provide valuable insights into the envelope of climate variability on time scales of significance to society today.Based on some palaeoclimatic records such as ice-cores,pollens,lake sediments,stalagmites and Chinese historical documentary records,the climate change around 2 kaBP is synthesized and its possible effects are also explored.
The results show an obvious climate change both in temperature and precipitation.The main conclusions are as follows:
(1) Around 2 kaBP in the Xinjiang Region,there is a temperature change from cold to warm,while in the other regions of China,there is a change from warm to cold.
(2) There is a discrepancy in the change in precipitation compared with the change in temperature.It shows a pervasive decrease in precipitation in most parts of northern China,while in southern China there was not an obvious change at the same time.It still tended to be wet there.
(3)This climate change contributed greatly to the instability of the West Han Dynasty,and coincided with many social events as well as an increase in several kinds of natural calamities,such as floods,droughts,grasshopper disaster,the shrinking of suitable cultivatable land and an obvious decrease of the population.
(4)This climate change around 2 kaBP may be driven by solar activity,atmospheric circulation and volcanic activities.During this period,the solar activity was relatively weak.Also in this period there were several volcanic eruptions both in China and foreign countries.Both of these factors may have led the climate to be cold and dry in most parts of China.
(5)This climate change proves that even in a warm period an abrupt climate change may take place just as in the cold periods.And it also provides evidence that the climate change in China is in phase with some other regions in the world.This knowledge can help us to take adaptive measures for future global change.