Description: Based on the study of 10 sediment cores and 40 core-top samples from the South China Sea (SCS) we obtained proxy records of past changes in East Asian monsoon climate on millennial to bidecadal time scales over the last 220,000 years. Climate proxies such as global sea level, estimates of paleotemperature, salinity, and nutrients in surface water, ventilation of deep water, paleowind strength, freshwater lids, fluvial and/or eolian sediment supply, and sediment winnowing on the sea floor were derived from planktonic and benthic stable-isotope records, the distribution of siliciclastic grain sizes, planktonic foraminifera species, and the UK37 biomarker index. Four cores were AMS-14C-dated. Two different regimes of monsoon circulation dominated the SCS over the last two glacial cycles, being linked to the minima and maxima of Northern Hemisphere solar insolation. (1) Glacial stages led to a stable estuarine circulation and a strong O2-minimum layer via a closure of the Borneo sea strait. Strong northeast monsoon and cool surface water occurred during winter, in part fed by an inflow from the north tip of Luzon. In contrast, summer temperatures were as high as during interglacials, hence the seasonality was strong. Low wetness in subtropical South China was opposed to large river input from the emerged Sunda shelf, serving as glacial refuge for tropical forest. (2) Interglacials were marked by a strong inflow of warm water via the Borneo sea strait, intense upwelling southeast of Vietnam and continental wetness in China during summer, weaker northeast monsoon and high sea-surface temperatures during winter, i.e. low seasonality. On top of the long-term variations we found millennial- to centennial-scale cold and dry, warm and humid spells during the Holocene, glacial Terminations I and II, and Stage 3. The spells were coeval with published variations in the Indian monsoon and probably, with the cold Heinrich and warm Dansgaard-Oeschger events recorded in Greenland ice cores, thus suggesting global climatic teleconnections. Holocene oscillations in the runoff from South China centered around periodicities of 775 years, ascribed to subharmonics of the 1500-year cycle in oceanic thermohaline circulation. 102/84-year cycles are tentatively assigned to the Gleissberg period of solar activity. Phase relationships among various monsoon proxies near the onset of Termination IA suggest that summer-monsoon rains and fluvial runoff from South China had already intensified right after the last glacial maximum (LGM) insolation minimum, coeval with the start of Antarctic ice melt, prior to the d18O signals of global sea-level rise. Vice versa, the strength of winter-monsoon winds decreased in short centennial steps only 3000-4000 years later, along with the melt of glacial ice sheets in the Northern Hemisphere.

Description: Past sea surface temperatures (SST) in the northern and southern areas of the South China Sea have been reconstructed for the past 220 kyr using the UK37 alkenone index. The SST profiles follow the glacial/interglacial pattern exhibiting differences between Last Glacial Maximum and Holocene that are 1°-3°C larger than those observed at the same latitudes in the Atlantic and Pacific Oceans. In Termination I both planktonic foraminiferal d18O and SST exhibit well-defined Bølling-Allerød and Younger Dryas events with temperature differences between both periods of 0.8° and 0.4°C in north and south, respectively. SSTs record a constant north-south difference of 1°C in the interglacials and nearly 2.5°C in the glacial stages. These differences define two distinct climatic and water circulation patterns that correspond with glacial/interglacial sea level oscillations which opened and closed water exchange with the tropical Indo-Pacific Ocean through the present Sunda Shelf

Description: Over the last deglaciation there were two transient intervals of pronounced atmospheric CO2 rise; Heinrich Stadial 1 (17.5-15 kyr) and the Younger Dryas (12.9-11.5 kyr). Leading hypotheses accounting for the increased accumulation of CO2 in the atmosphere at these times invoke deep ocean carbon being released from the Southern Ocean and an associated decline in the global efficiency of the biological carbon pump. From core TAN1106-28 we present new G. bulloidies boron isotope and Mg/Ca derived sea surface pH and pCO2 concentrations. Trace element analysis was performed on a ThermoScientific Element 2 ICP-MS at the University of Southampton using the method described by Henehan et al. (2015). Isotopic analysis was performed on a ThermoScientific Neptune MC-ICPMS at the University of Southampton following the methods of Foster (2008) and Foster et al. (2013).

Description: Over the last deglaciation there were two transient intervals of pronounced atmospheric CO2 rise; Heinrich Stadial 1 (17.5-15 kyr) and the Younger Dryas (12.9-11.5 kyr). Leading hypotheses accounting for the increased accumulation of CO2 in the atmosphere at these times invoke deep ocean carbon being released from the Southern Ocean and an associated decline in the global efficiency of the biological carbon pump. From core ODP1090 we present new G. bulloidies boron isotope and Mg/Ca derived sea surface pH and pCO2 concentrations. Trace element analysis was performed on a ThermoScientific Element 2 ICP-MS at the University of Southampton using the method described by Henehan et al. (2015). Isotopic analysis was performed on a ThermoScientific Neptune MC-ICPMS at the University of Southampton following the methods of Foster (2008; doi:10.1016/j.epsl.2008.04.015) and Foster et al. (2013; doi:10.1016/j.chemgeo.2013.08.027).