3. The Conceptual Model and Indicators of the Impacts of Historical Climate Changes in China

China is a country that has great potential for the research of impacts of past climate change. To study the process and mechanism of the impacts of historical climate change on social economy in China, a concept model and methodologies for reconstructing social-economic sequences were developed. The historical climate change impacts in China could be attributed as a food security issue. Using the concepts of food security, resilience, vulnerability and adaptation, a food security based concept model was designed to illustrate the impact-response processes of historical climate transmitted in the subsystems of production, economy, population and society. A gradation methodology on the base of semantic differential was developed for converting the historical literal records about social and economic descriptions to graded sequences. The methods of gradation and frequency could be used to reconstruct the historical social-economic sequences with the same time resolution, duration, and continuity as the climate sequences to represent the subsystems of agricultural production, population, economy, society in the history of China.