Search

Land use and land cover change (LUCC) is not only a vital form of global change, but through biogeophysical and biogeochemical mechanisms, it also has a strong impact on the global and regional climate and environment change. The existing historical LUCC datasets still have many uncertainties that cause errors in climate and environment simulations. Reconstruction of historical LUCC on the regional scale is essential for improving the precision of global and national LUCC. In this study, we combined existing datasets with historical statistics and survey data to reconstruct cropland change in North China Plain Area over the past 300 years. Following systematic steps, a range of original methods from data sources and methods comparison, data re-calibration, time slices selection, data supplement, to cropland area fraction calculation were used. The cropland area at the county level was allocated into grid cells of 10 km × 10 km so as to achieve a high spatial resolution and precision. The results show that the cropland area change in North China Plain Area can be classified into two main stages: steady increase before 1954 and rapid decrease after 1954. The spatial distribution of cropland change over the past 300 years corresponded to the patterns of the total cropland change in North China Plain Area. From the late 17th century to the 1980s, the cropland area fraction in the plains increased and the cropland expanded to the hilly and coastal areas gradually. After that, the cropland area fraction in the plains decreased, especially in the southeastern of North China Plain Area. The total cropland area in North China Plain Area of our study is close to the results of most previous studies but the maps generated based on our dataset present local difference of cropland distribution more clearly than a recent important global dataset HYDE3.2. Our dataset of cropland area at 10 km × 10 km grid scale can also be used directly in climate and environment simulations to improve the data precision in North China Plain Area.

The present study aims to compare quantitatively the similarities and differences of transmission processes extending from climate change to grain harvests and economies (macro-economy and fiscal balance) between the Han (206 BC–AD 220) and Tang (AD 618–907) dynasties of China. It is found that both the Han and Tang periods displayed close positive correlations among temperature, grain harvest, macro-economy and fiscal balance and conveyed a positive feedback–oriented transmission pattern with the upgrade of climatic impact level from grain harvest to economic system. Compared with the Han period, the overall linkages among indicators weakened during the Tang period, particularly for the correlation between grain harvest and fiscal balance. The mean temperature during the Tang period was slightly higher but had greater multidecadal variability, coinciding with better performance (and less variations) of macro-economy and fiscal balance (particularly for cold units) and higher variations of grain harvest. It displayed relatively little difference for the main pathways that could be interpreted as climatic impacts during the warm units between the Han and Tang periods, and both approximately 33% of the decades for warm units (100%) ending with fiscal balance/surplus were more likely to be associated with the impacts of temperature change. The difference mainly lies in cold units in the links of ‘cold → poor harvest’ and ‘poor harvest → macro-economic depression’ through the pathway of ‘cold → poor harvest → macro-economic depression/normal economy → fiscal deficiency’. Overall, macro-economy and fiscal system of the Tang period displayed less sensitivity to temperature change and agriculture production in cold period. Those patterns might be related with the unique socio-economic situations such as agricultural fragmentation, southward shift of economic resource and tax system reform during the later Tang Dynasty.

The social impact of past climate change is one of the key areas of study relating to global climate change, particularly its ability to provide valuable lessons for dealing with ongoing challenges of global climate change. Drawing on the abundant historical literature, many recent studies have examined the social impacts of climate change in China during the past 2000 years. This paper reviews the main progress of these studies in three parts. First, a concept model based on the food security in relation to global climate change has been constructed, which can then be used to interpret impact-response processes of climate change in the history of China. Second, we derive a methodology for quantifying the impact of historical climate change, drawing on a series of 4 key social and economic sequences at a 10-year resolution. These have been reconstructed based on the semantic differential method over the past 2000 years in China. Third, using a variety of statistical analyses, we update the understanding of climate impacts throughout the history of China. The overall impacts of climate were negative in the cold periods and positive in the warm periods, at decadal to centennial scales during Chinese history. However, the impacts seemed a mixed blessing both in the cold or warm periods. The social-economic development and population growth in warm periods would intensify the natural resource shortage and disequilibria in the human-environment system, especially when encountering abrupt climate changes. Adaptation to adverse climate change could not only help people to avoid hardship whilst maximizing profits, but also expanded the capabilities for the continual development of Chinese civilization.

Investigations of the relationships between climate and human history often place more emphasis on the science of climate change than on understanding human socio-economic processes, and therefore suffer from superficial results and an unbalanced perspective. This is partly due to the lack of high-resolution data concerning long-term socio-economic processes. Here, we base our study of climate and society on a series of 2130-yr-long economic proxy data from China with decadal resolution. The economy was associated significantly with temperature and precipitation at the two predominant bands of 100 and 320 yr. The phase transition of economic states was influenced positively by long-term temperature change combined with triggering effects of short-term changes in precipitation. However, climatic impact on economy should not be recognized as simple causality but some driving-response relation coupled with meditation by human agency at multiple scales. A model of ‘adaptive cycles’ implies, in relative to the developing phases, climate–economy relationship during the declining phases was more easily moderated by slower processes like rigidity and faster processes like unrest. From a more-macro perspective, climatic driving for the macro-economic cycles was moderated by larger and slower processes like social memory, spatial shifting of key economic areas, and social–technical advance.