To assess the environmental changes caused by global warming in the 21st century and their impact on rice-producing societies in Monsoon Asia, previous research and recent international and Japanese activities are reviewed and the problems to be studied are summarized.
Since the 1920s, many studies have been conducted on regional geography in Monsoon Asia, mainly by European and American geographers, demographers, agricultural economists, and sociologists. They concluded that only rice-producing societies can sustain high-density populations in Monsoon Asia. In other words, high population density is a result of rice cultivation. Is this conclusion still valid in the 21st century?
Since World War II, synthetic studies on special topics by scientists from many fields have been carried out. Examples include rice-cultivating societies in Thailand, agricultural cultivation forms in Monsoon Asia, etc. From the 1970s, international meetings have been convened on the topic of rice and climate, and from the 1980s on the relation of rice cultivation with global change. In the 1990s, global and national food security problems have become a main topic. It is believed that these problems should be discussed from the viewpoint of relatively homogeneous regions with similar cultures, history, and recent experience in industrialization/urbanization, as in the regional scale of Monsoon Asia. International programs like the International Geosphere-Biosphere Programme (IGBP) and Human Dimension Programme (HDP), and the international organizations such as SCOPE, OECD, FAQ, and WMO have studied topics related to rice cultivation and the influence of global change, but the human dimensions were not the main focus in those studies.
After discussing the range and definition of Monsoon Asia, further issues to be studied are summarized. They include: 1) consumption, self-sufficiency, and demand for rice; 2) rice production and El Nino; 3) the rice cropping calendar; and 4) the historical development of paddy cultivation. In conclusion, the following three topics are the most urgent subjects: 1) urbanization/indus-trialization and rice-producing societies in Monsoon Asia; 2) assessment of the impact of climatic fluctuations/changes on paddy production potential; and 3) influence of and or humid climate tendencies on regional/cultural development.

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This paper consideres changes in grain crop production in China during 1949-1996, with particular emphasis on the reform period, i.e., 1978-1996, from the aspects of grain output, sown area, and yield. Data on cultivated land area from the Semi-detailed Land Use Survey and the Detailed Land Use Survey, which have good credibility in China, are used to correct the sown area and yield given in statistical yearbooks. Based on the above data, the authors considered the relationship between the production of different crop varieties and the reasons for their cultivation in different periods and regions. In addition to population growth, natural hazards and technological improvements, the following reasons have been found important for grain production:
1) The main reason for the shift from low-yield crops to high-yield crops varies by period. Before the reform, it was mainly caused by the great pressure of food demand induced by rapid population increase. After 1978, the main reason was the change in dietary structure.
2) Rapid urbanization since the 1980s has been a serious challenge to grain production in China.
The amount of cultivated land has decreased because of urban sprawl. The opportunity cost of grain production has risen swiftly because of the rapid development of nonagricultural sectors, which deprives the agricultural sector of resources, such as investment and labor.

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The lower Yangtze River Basin is one of the most developed regions in China. Its land use shows interesting patterns from the sustainable development point-of-view. Applying a two-way layout statistical model, this paper examines the temporal and spatial changes in land use in the region.
The major findings are as follows:
(1) Temporal changes in land use can be grouped into three distinctive periods: 1986 to 1989; 1990 to 1991; and 1993 to 1994. These changes are mainly influenced by the dynamics of the domestic political economy (e. g., governmental policies, capital investment, etc.) and the environment of the international political economy.
(2) The region can be divided into six zones in terms of spatial changes in land use: 1) Shanghai; 2) the triple cities of Wuxi/Suzhou/Changzhou and the south of the Yangtze River; 3) Nanjing; 4) Nantong, Yangzhou and Zhenjiang along the Yangtze River; 5) Yancheng and Huaiyin; and 6) Xuzhou and Lianyungang in the north of the Yangtze River Basin. The spatial patterns of land use are affected by changes in the built-up and agricultural areas, rather than by changes in forestry areas.
(3) The major determinants of land use change in the lower Yangtze River Basin are population, economic growth, urbanization, infrastructure construction and capital investment.

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