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China is the country with the most population in the world, and its climate is extremely diverse due to tremendous differences in latitude, longitude, and altitude, ranging from tropical in the far south to subarctic in the far north and alpine in the higher elevations of the Qinghai-Tibetan Plateau. Accurate assessment of its modern climate change is conductive to addressing global warming threat. Along with the development of Past Global Changes (PAGES) research, the focus has changed from paleo-climate reconstructions to using paleo-data for assessing the present and predicting the future. Previous studies have been devoted to climate change assessment using modern climate observations and simulations. This paper presents a new assessment approach based on the mid-Holocene, which provides a naturally oriented warming that can be compared to modern human-made global warming. A variety of climatic data, including modern observations, paleo-climate records, CMIP5 (Coupled Model Intercomparison Project Phase 5) and PMIP3 (Paleoclimate Modelling Intercomparison Project 3) simulations, as well as lake level models, were applied in this synthesis. Numerical climate classification was introduced to evaluate climate change impacts to Chinese climate zones on various time scales. The results show that winter and summer seasons have different response to the naturally oriented mid-Holocene warming but human-made global warming makes the warming trend appear in all seasons. Temperate and continental dry winter climates expand dramatically during the mid-Holocene warm period; however, the future global warming could have few impacts to Chinese climate zones. Furthermore, the East Asian summer monsoon was strengthened obviously by the mid-Holocene warm climate and strong low-latitude insolation. There is no consistent trend both for the winter and summer monsoon on the background of human-made global warming. In this study, a new benchmark was established based on paleo-climate to evaluate the impacts of human-made global warming. [ABSTRACT FROM AUTHOR]

Climate warming and subsequent climate extremes have a wide impact on ecosystems and economic society. Scientifically quantitative assessment on climate change risks is an urgent issue attracted the attention of academics and decision-makers. In this paper, the theory of climate change risks was sorted out based on the three component elements of hazard, vulnerability, and exposure. Moreover, the idiomatic assessment methods and their applicability were systematically summarized. Comprehensive analysis found that the impacts of climate change generally showed a negative trend that was more harm than benefit, and further warming would aggravate the risk over China which was manifested to be more prominent in some sensitive sectors and key regions to climate change. Accessible management of the climate change risk should be engaged in effectively improving the methods of comprehensive identification, strengthening the mechanism and quantitative assessment, recognizing the temporal and spatial variation of components related to climate change risk, and reducing the uncertainty of climate change projection. • Theoretical framework of climate change risk was formed based on hazard, vulnerability, and exposure. • Assessment methods of climate change risk and their applicability were systematically summarized. • Climate change risk levels were analyzed in sensitive sectors and key regions over China. • In China, impacts of climate change were more harm than benefit while more warming was very likely to aggravate the risk. [ABSTRACT FROM AUTHOR]