FAROUK EL-BAZ AWARD FOR DESERT RESEARCH: MODERN PROCESSES AND LATE QUATERNARY CLIMATIC CHANGES IN THE DESERTS OF NORTHERN CHINA

Irrespective of the classification standard of climate applied, the Chinese landmass is characterized by extensive arid and semi-arid areas at present time, and the deserts in northern China account for the largest portion of drylands in the middle latitudes. Compared with many other desert regions of the world, studies carried out within the deserts in China are still very limited and much of their environmental history is inferred from sedimentary sequences located outside. In this paper we would like to begin by introducing our recent studies on the modern hydrological processes in the Badain Jaran Desert in the western Inner Mongolia. The annual amount of evaporation in this desert was reported to be from 2600 mm to ~4000 mm in earlier publications. Applying a modified Penman equation commonly used for the lakes of drylands by hydrologists, we re-estimated the monthly evaporation rate in the desert on the basis of climate records in this region from the last 40 years. It came out that the mean annual evaporation should be ~1040 mm from lake surface and ~100 mm from the land surface in the southeastern part of this desert. Based on this new estimate, we would like then to argue that the Quaternary landscape changes in the deserts of China could be indicative of on-site and/or regional precipitation changes relating to the fluctuations of East Asian monsoon system and/or North Hemisphere westerlies. Different from the widely accepted idea of a continuous trend of aridification occurring in the Cenozoic in the interiors of Asia due to uplifting of the Tibetan Plateau, geomorphological and sedimentological evidence suggests that the climate has experienced distinct changes in the drylands of China in the Late Quaternary. Large areas in western China, presently hyper-arid, were wetlands or at least less arid between 40 and 30 ka. Some of the Chinese sand seas experienced wetter conditions even during the last glacial maximum. While high-resolution interpretations of Quaternary environments in deserts are still controversial, it was quite likely that it was also more humid in the deserts of western China during some periods of early to middle Holocene. The aridity in Asian interiors has been probably destroyed by repeated, short-term non-desert environments at least since Late Pleistocene.