Scientists can carry out a broad range of geological, geochemical, and geophysical measurements that provide the basis for investigations of past climate change in North China, including geologic observations in the field and measurements by microscopy in the laboratory (An Zhisheng, Zhu Yizhi, and Zhou Jie, PIs), spore pollen analysis (Li Xiaoqiang, PI), radiocarbon dating (Zhou Weijian and Jiang Yu, PIs), stable isotope measurements (Liu Yu and Su Fuqin, PIs), thermo luminescence dating (Xie Jun, PI), magnetostratigraphy (Zheng Hongbo, PI), and chemical element analysis of present day dust aerosol (Zhang Xiaoye, PI).
Laboratory scientists have now established proxy sequences of paleoclimates and environments on time scales of 2.5 million years, 150,000 years, and 20,000 years B.P. for the Loess Plateau. Three of the major results are noteworthy:
A theory has been put forth that paleo-Asian monsoon is a controlling factor in environmental changes in central China, for example, that variation in monsoon circulation may have caused variation in temperature, moisture, soil conditions, and plant growth during the past 20,000 years.
A distributional model has been developed for paleoenvironments around 18,000 years before present and at the Holocene optimum 9,000 to 5,000 years before present.
An abrupt event about 10,000 to 11,000 years before present has been discovered when the summer monsoon weakened and the winter monsoon strengthened, corresponding to the Younger Dryas in the North Atlantic region.
Scientists have actively sought to establish collaboration with researchers at other institutions, including laboratories in the United Kingdom and the United States. An Zhisheng and Stephen Porter, University of Washington, are conducting a comparative study of the chronology and dynamics of Late Quaternary climate and environmental changes between central China and the northwestern United States. Based on research undertaken for the China and America Air-Sea Experiments (CHAASE), An Zhisheng, Zhang Xiaoye, and Richard Arimoto, University of Rhode Island, are conducting a comparative study of the atmospheric transport of soils by focusing on the interannual variability in the atmospheric dust concentrations and the meteorological conditions responsible for the concentration differences (Appendix C).
Results of the laboratory's research have been published in Chi-