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This paper documents a 7800-year proxy record from the Shenjiadian peatland on the Sanjiang Plain in Northeast China. High-resolution plant macrofossil and colorimetric humification methods were used to reconstruct the vegetation and hydrologic history from a 193 cm-long sedimentary profile. Detrended correspondence analysis (DCA) was applied to transform the raw plant macrofossil data into latent indices of peatland water level. The vegetation community transited from an Equisetum fluviatile community to a Carex lasiocarpa community at approximately 3800 cal yr BP and was followed by a Carex-shrub community at approximately 480 cal yr BP. Based on the plant macrofossil DCA axis 1 scores and humification values, we distinguished four hydrologic periods: a wet period from 7800 cal yr BP to 4500 cal yr BP, dry periods up to 1600 cal yr BP, drier periods until 300 cal yr BP, and the driest period from 300 cal yr BP until the present. Through a comparison with other climate records, we suggest that the East Asian summer monsoon (EAM) was the main driving force for vegetation and water level changes to the Shenjiadian peatland through its impacts on precipitation. [ABSTRACT FROM AUTHOR]

This paper is a review of studies of abrupt climate changes (ACCs) during the Holocene published during the past ten years. North Atlantic cold events are indicators of ACCs. As indicated by North Atlantic ice-rafted debris (IRD), there were nine confirmed cold events during the Holocene, occurring at 11.1 kyr, 10.3 kyr, 9.4 kyr, 8.1 kyr, 5.9 kyr, 4.2 kyr, 2.8 kyr, 1.4 kyr, and 0.4 kyr respectively according to most representative results from Bond et al. (1997). However, the identification of chronology has been made with some uncertainties. Considerable climatic proxy data have shown that, during the cold events, substantial climate abnormalities have occurred widely across the globe, particularly in the areas surrounding the North Atlantic. These abnormalities were in the form of high-latitude cold in the both hemispheres, expansion of the Westerlies to low latitudes, drought in the monsoon regions, recession of summer monsoons, and intensification of the winter monsoons. Studies have indicated that the four ACCs occurring in the early Holocene may be related to freshwater pulses from ice melting in the northern part of the North Atlantic, and the other five ACCs that occurred during the middle and late Holocene may be related to the decreased solar activity. [ABSTRACT FROM AUTHOR]