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The catastrophic demise of the Aral Sea in the late twentieth century has stimulated significant international efforts to understand the geological, hydrological, and climatological controls on lake level at timescales ranging from years to millennia. Here we extend this time range to the Late Pleistocene with sedimentological, chronological and paleontological results from a core that dates from ca. 17.6 kyr cal BP. To our knowledge, this Aral Sea core (B-05-2009) is the oldest directly-dated sediment record with multiple late Pleistocene 14C dates currently available from the region. The core shows that the modern Aral Sea formed at least as early as the end of the Last Glacial Maximum. The main source of water was most likely glacial meltwater from the Tian Shan, Pamir, and other distant mountain systems in the modern day Aral Sea watershed, carried by the Syr Darya and Amu Darya rivers. The Late Pleistocene section of the core contains ostracods and foraminifera throughout, providing evidence that the lake supported life since its inception. Our chronology suggests a relatively high average sedimentation rate at the onset of lake development, and a significant sedimentation hiatus around the time of the Pleistocene/Holocene boundary.

We report here on a previously unpublished sediment core from Qinghai Lake, China, that preserves a continuous record of sedimentation for the past 40 ka. A striking feature of the record is a set of distinct meltwater events recorded at 35, 19 and 14 ka respectively. These events are manifest as distinct pulses of relatively old organic radiocarbon in the sediments. We interpret these as a signal of glacial melting in the Qinghai Lake watershed. The meltwater signals are closely correlated to temperature and precipitation records associated with deglaciation. The events at 19 ka and 14 ka correspond to well-established high latitude Melt Water Pulse (MWP) events during Marine Isotope Stage (MIS) 2, and the 35 ka event corresponds to a period of pervasive high lake levels in western China during late MIS 3. We interpret these anomalous dates as the result of relatively old carbon that was destabilized by the glaciers, and released into the lake as the glaciers melted. The data indicate that this process takes thousands of years. We expect that the approach employed here to identify these events is generally applicable to any lake system with a significant glacial meltwater component.

Paleoclimate change research routinely takes advantage of a variety of climate proxies. Each proxy responds to climate in its own way and a combination of proxies offers the best means of understanding past climate at a given site. Here we present iodine variation patterns in one classical loess-paleosol sequence in the Chinese Loess Plateau to develop a new proxy that responds to climate-induced changes in the source availability, transport dynamics and depositional environment of iodine. Our iodine variation provides a continuous record for the past ∼260 kyr, and is highly correlated with traditional climate proxies, including magnetic susceptibility, mean grain size and organic matter content. We attributed the variations of the iodine record to past climate changes particularly in aspects of coupled air-sea circulation, transport dynamics, and depositional retention on the Chinese Loess Plateau. We propose that geochemistry of iodine variation provides a new tool for assessing paleoclimate changes in aspects of large-scale air-sea circulation mechanism, global iodine transport dynamics, and depositional environment as particular enrichment factors in the Chinese Loess Plateau.

The Tianchi Volcano, located on the border between China and North Korea, produced a massive Plinian eruption of Volcanic Explosivity Index (VEI) 7 around 1000 AD, which is referred to as “the Millennium eruption of Tianchi Volcano”. Until now, this volcanic eruption has not been well dated. In this paper, we report a series of new calibrated dates using wiggle-match dating from carbonized logs collected from fallout deposits on the southern and northern flanks of the Tianchi crater. Fifty AMS 14 C ages of tree rings from two logs were obtained for the Hengshan site, south of the Tianchi crater ( Fig. 1 ). These yielded a high-precision wiggle-match date of 921–941 cal AD (95.4%) for the Millennium eruption. Thirty-two AMS 14 C ages of tree rings of other two logs from the Dongfanghong site, north of Tianchi crater ( Fig. 1 ), produced an age range for the volcanic eruption from 921 to 942 cal AD (95.4%). A combined date for the four carbonized logs produced an age of 923–939 cal AD (95.4%) for the Millennium eruption. Moreover, an exact date of late autumn, 938 AD or early spring, 939 AD is suggested based on the impact of the Tianchi Volcano on global climate, especially East Asian climate, and the complete outermost rings of these four trees killed in the eruption.

East Asian monsoon (EAM) evolution during the last deglaciation has been shown repeatedly to be aligned with paleoclimatic changes in the North Atlantic, based on climate reconstructions comparing Asian speleothem records with Greenland ice cores. In contrast to this finding, paleoclimatic reconstructions based on Lake Suigetsu sediment cores suggest that past EAM variability in Japan was not always coherent with climatic variability recorded in Greenland ice cores. We resolve this discrepancy using an absolute-dated stalagmite δ 18 O record that covers the period between 15.5 and 10.7 thousand years before present (ka, before AD 1950). This stalagmite record is from nearby Maboroshi cave, Japan, and shows climate changes that are synchronous with those of Chinese caves and Greenland ice cores. Our results support an effective teleconnection between low- and high-latitudinal climate systems during the transitions into the Bolling–Allerod (BA) warming at 14.6 ka and the Younger Dryas cooling at 12.8 ka in the North Atlantic. However, our results also indicate monsoonal intensification during the BA, coincident with decreasing temperatures in Greenland from 14.6 to 12.8 ka. We explain this decoupling as a result of the interhemispheric bipolar seesaw climate system. Discrepancies between Lake Suigetsu radiocarbon age data sets and other radiocarbon calibration archives can also be removed when our Maboroshi record is used to adjust the Lake Suigetsu age model, as well as resolving temporal ambiguities in the Lake Suigetsu paleoclimate record.

At Urelapa island, Vanuatu, sea-level rise and a tectonic uplift of ∼3 mm yr −1 have controlled water depth and the colonization and reef development on a substrate from 23 until 6 cal kyr BP. Analysis of coralgal assemblages offers insights on the mode of reef growth and on water depth over the reef for the studied period. Those assemblages, precisely dated by the 230 Th/ 234 U method, give valuable information on the rate and timing of sea-level rise since the Last Glacial Maximum. The Urelapa reef sequences are characterized by upwards replacement of reef frameworks which indicates changes in wave energy through time. The sudden acceleration of sea-level rise associated with meltwater pulse-1B at around 11.3 cal kyr BP is marked by a change in reef growth strategy, from a keep-up mode to a catch-up mode. We examine the delay in timing of the occurrence of suitable substrates, the role of paleoceanographic factors and the influence of possible jumps in sea level.