Changing summer monsoon and environment in tropical Asia

本次热带亚洲夏季风与环境长期变化研究项目是应国际科学理事会国际地球物理物理联合会的IGBP计划，旨在阐明全球尺度环境变化与人类活动的关系。该项目的第一个目标是恢复亚洲热带地区在最后一次间冰期后的环境变化，时间尺度为数千年。为了实现这一目标，我们对印度、泰国和印度尼西亚西南部自上一次间冰期以来容易受到印度洋西南季风影响的微地貌、土壤和植被进行了实地研究。因此，我们制作了各地区晚第四纪以来环境变化的天气年表。为了进一步重建陆地古环境，需要发展一些方法学/技术，如古医学、地貌学和孢粉学。第二个目标是区分自然环境变化和人为影响。我们还收集了相关机构发布的考古报告和历史记录中的数据，以澄清自然环境与人类影响之间的关系。印度、印度尼西亚、泰国和中国利用地貌和孢粉记录进行的研究也表明了人类对陆地环境的影响，特别是砍伐森林和农业的影响。为了进一步研究西南季风的变化，有必要将实地调查获得的陆地数据与印度洋深海钻探和喜马拉雅冰川波动的岩心样品分析数据进行比较，以阐明西南季风在大范围内的变化。从气候学的角度出发，研究高纬大气环流与低纬大气环流的相互关系对于理解全球环境变化的机制是必要的。

This research project on long-term change in summer monsoon and environment of tropical Asia was planned in response to IGBP of ICSU to clarify the relationships between global-scale environmental change and mankind activities.The first objective of this project is to restore the environmental change of tropical Asia after last interglacial with time scale of several thousand years. In order to achieve the objective, we conducted field research for microrelief, soils and vegetation in southwestern part of India, Thailand and Indonesia where have been apt to be influenced by southwestern monsoon from the Indian Ocean since last interglacial. As a result, we made synoptic chronological tables on environmental change after the late Quaternary in each region. For further reconstruction of terrestrial paleoenvironments, it is required to develop some methodology / techniques, for example, paleopedology, geomorphology and palynology.The second objective is to distinguish natural environmental change from artificial effects. We also collected data from archeological reports and historical records published by concerned institutes to clarify the relation between natural environment and human influence. Human impact on terrestrial environment, particularly that of deforestation and agriculture, was also indicated by the studies in India, Indonesia, Thailand and China, using geomorphological and palynological records.For the further study, it is necessary to elucidate the change in southwestern monsoon over wide area by comparing the data on land which we got from the field survey with the data from the analysis for core samples of deep sea drilling in the Indian Ocean and glacial fluctuation in Himalaya. From the view point of climatology, the studies of mutual relationship between high-latitude and low-latitude atmospheric circulation are necessary to understand global mechanism of environmental change.