The Long-term Trend And Abrupt Changes Of Climate During The Last Millennium In Eastern China

Climate change during the last millennium is a key period to link geological record of million or thousand years to instrumental data. Reconstruction of climate change in this period provides a historical reference scenario to analyze current laws of climate change and simulate the future trend. It is of great significance to the understanding of current and future climate.In this paper, we took Chinese Eastern monsoon region as the study area and long-term trends and abrupt changes of the last millennium in climate change as the research object. Compared various climatic proxies and historical documents to reveal the main features of climate change in different regions of the monsoon, and explored the possible driving factors.The results show that:1) Climate change in the area of eastern China monsoon during the last millennium in general experienced warm-cold-warm three stages. Medieval Warm Period was not a continuous warm period. It had a cold period in the12th century in the middle. Little Ice Age was not a continuous cold period. It had a warm period in the14th century and18th century. It had a cold period in the17th century and19th century. The transition of the first warm period in Medieval Warm Period to the cold period in the12th century was abrupt change. The transition of the warm period in the14th century to the first cold period in Little Ice Age was abrupt change.2) The configuration of temperature and humidity changes in eastern monsoon region during the last millennium was warm and dry-cold and wet-warm and wet. Northern Most Region was warm and wet-cold and dry-warm and wet. North China area was warm and dry-cold and wet-cold and dry-cold and wet-warm and dry. The middle and lower reaches of Yangtze River was warm and dry-cold and wet-cold and dry-cold and wet-warm and wet. Southern China area was warm and dry-cold and wet-cold and dry-cold and wet-cold and dry-cold and wet-warm and wet.3) We got two main spatial distribution types of the average annual temperature in the eastern monsoon region since1951. Typel:it was warm (cold) in the whole region. Type2:it was warm (cold) in the south and cold (warm) in the north. We got three main spatial distribution types of the summer precipitation,too. Typel:there was flood (drought) in the whole region. Type2:there was flood (drought) in the south and north and drought (flood) in the central part. Type3:there was flood (drought) in the south and drought (flood) in the north. The third time coefficients were detected sharp changes occurs in the early1970s. It changed from "Southern drought and Northern flood" to the opposite. In recent years, the precipitation characteristics of it had been weakened, and had the trend to re-convert to "Southern drought and Northern flood".4) The main driving force of climatic change especially the temperature change was solar and volcanic activity. Changes in precipitation in the Yangtze River and southern China had consistency, may be controlled by the double impact of North Atlantic sea surface temperature and the Indian Ocean-the western Pacific sea surface temperature. The precipitation in North China area was also associated with the North Atlantic sea surface temperature. The strength of the East Asian monsoon and the South China Sea monsoon were major factors in the second spatial distribution type of summer precipitation in eastern monsoon region.