scholarly journals Human Migration through Bottlenecks from Southeast Asia into East Asia during Last Glacial Maximum Revealed by Y Chromosomes

PLoS ONE ◽  
2011 ◽  
Vol 6 (8) ◽  
pp. e24282 ◽  
Author(s):  
Xiaoyun Cai ◽  
Zhendong Qin ◽  
Bo Wen ◽  
Shuhua Xu ◽  
Yi Wang ◽  
...  
Keyword(s):  
Southeast Asia ◽  
East Asia ◽  
Last Glacial Maximum ◽  
Glacial Maximum ◽  
Human Migration ◽  
Last Glacial ◽  
Y Chromosomes

scholarly journals Modeling Dust Direct Radiative Feedbacks in East Asia During the Last Glacial Maximum

Atmosphere ◽  
2019 ◽  
Vol 10 (3) ◽  
pp. 146 ◽  
Author(s):  
Xugeng Cheng ◽  
Xiaoning Xie ◽  
Zhengguo Shi ◽  
Xinzhou Li ◽  
Tianliang Zhao ◽  
...  
Keyword(s):  
East Asia ◽  
Last Glacial Maximum ◽  
Glacial Maximum ◽  
Sensible Heat ◽  
Dust Emissions ◽  
Last Glacial ◽  
Current Climate ◽  
Radiative Feedbacks ◽  
The Last Glacial Maximum ◽  
The Last Glacial

In this study, using the fourth version of the Community Atmosphere Model (CAM4) with a bulk aerosol model parameterization (BAM) for dust size distribution (CAM4-BAM), East Asian dust and its direct radiative feedbacks (DRF) during the Last Glacial Maximum are analyzed by intercomparing results between the experiments with (Active) and without (Passive) the DRF. This CAM4-BAM captures the expected characteristics that the dust aerosol optical depth and loading over East Asia during the Last Glacial Maximum (LGM) were significantly greater compared to the current climate. A comparative analysis of the Active and Passive experiments reveals that consideration of the dust–radiation interaction can significantly reduce dust emissions and then weaken the whole dust cycle, including loading, transport, and dry and wet depositions over East Asia. Further analysis of the dust–radiation feedback shows that the DRF decreases surface sensible heat, mainly owing to the negative surface forcing induced by dust with a value of −11.8 W m−2. The decreased surface sensible heat weakens the turbulent energy within the planetary boundary layer and the surface wind speed, and then reduces the regional dust emissions. This process creates a negative DRF–emission feedback loop to affect the dust cycle during the LGM. Further analysis reveals that the dust emissions in the LGM over East Asia were more reduced, with amounts of −77.2 Tg season−1 by the negative DRF–emission feedback, compared to the current climate with −6.8 Tg season−1. The two ratios of this reduction to their emissions are close to −10.7% for the LGM and −7.5% for the current climate.

scholarly journals A cosmogenic nuclide chronology of Cordilleran Ice Sheet configuration during the Last Glacial Maximum in the northern Alexander Archipelago, Alaska

2021 ◽  
Author(s):  
Caleb K. Walcott ◽  
Jason P. Briner ◽  
James F. Baichtal ◽  
Alia J. Lesnek ◽  
Joseph M. Licciardi
Keyword(s):  
Continental Shelf ◽  
Last Glacial Maximum ◽  
Ice Sheet ◽  
Glacial Refugia ◽  
Glacial Maximum ◽  
Human Migration ◽  
Last Glacial ◽  
The North ◽  
Cordilleran Ice Sheet ◽  
Alexander Archipelago

Abstract. The late-Pleistocene history of the coastal Cordilleran Ice Sheet (CIS) remains relatively unstudied compared to chronologies of the Laurentide Ice Sheet. Yet accurate reconstructions of CIS extent and timing of ice retreat along the Pacific Coast are essential for a variety of reasons including paleoclimate modeling, assessing meltwater contribution to the North Pacific, and determining the availability of ice-free land along the coastal CIS margin for human migration from Beringia into the Americas. To improve the chronology of CIS history in the Alexander Archipelago, Alaska, we applied 10Be and 36Cl dating to boulders and glacially sculpted bedrock outcrops in areas previously hypothesized to have remained ice-free throughout the local Last Glacial Maximum (lLGM; 20–17 ka). Results indicate that these sites, and more generally the coastal northern Alexander Archipelago, became ice-free by 15.1 ± 0.9 ka (n = 12 boulders; 1 SD). We also provide further age constraints on deglaciation along the southern Alexander Archipelago and combine our new ages with data from two previous studies. We determine that ice retreated from the outer coast of the southern Alexander Archipelago at 16.3 ± 0.8 ka (n = 14 boulders; 1 SD). These results collectively indicate that areas above modern sea level that were previously mapped as glacial refugia were covered by ice during the lLGM until between ~16.3 and 15.1 ka. As no evidence was found for ice-free land during the lLGM, our results suggest that previous ice-sheet reconstructions underestimate the regional maximum CIS extent, and that all ice likely terminated on the continental shelf. Future work should investigate whether presently submerged areas of the continental shelf were ice-free.

scholarly journals The LGM surface climate and atmospheric circulation over East Asia and the North Pacific in the PMIP2 coupled model simulations

2007 ◽  
Vol 3 (3) ◽  
pp. 439-451 ◽  
Author(s):  
W. Yanase ◽  
A. Abe-Ouchi
Keyword(s):  
East Asia ◽  
Last Glacial Maximum ◽  
North Pacific ◽  
General Circulation ◽  
Glacial Maximum ◽  
Last Glacial ◽  
The North ◽  
The Last Glacial Maximum ◽  
The North Pacific ◽  
The Last Glacial

Abstract. The surface conditions and atmospheric circulation over East Asia and the North Pacific during the last glacial maximum have been investigated using outputs from several coupled atmosphere-ocean general circulation model in the PMIP2 database. During the boreal summer, the weakening of the high pressure system over the North Pacific and less precipitation over East Asia are found in most models. The latter can be attributed to reduced moisture transport. During the boreal winter, an intensification of the Aleutian low and southward shift of the westerly jet stream in the upper troposphere are found in most models. Some of the results in the present study seem to be consistent with the paleoclimatic reconstructions in the previous studies: pollen and lake-status records suggest dry climate over East Asia during the last glacial maximum, and part of the dust record has a signal that the East Asian winter monsoon was more strong and the westerly jet stream in the upper troposphere was further south during the last glacial maximum than at the present day. This result confirms that a coupled atmosphere-ocean general circulation model is a promising tool to understand not only the global climate but also the regional climate in the past.

Reconstructions of the past distribution of Testudo graeca mitochondrial lineages in the Middle East and Transcaucasia support multiple refugia since the Last Glacial Maximum

2021 ◽  
pp. 10-17
Author(s):  
Oguz Turkozan
Keyword(s):  
Middle East ◽  
Last Glacial Maximum ◽  
Glacial Maximum ◽  
Testudo Graeca ◽  
Last Glacial ◽  
The Past ◽  
Precipitation Seasonality ◽  
Multiple Refugia ◽  
The Last Glacial Maximum ◽  
The Last Glacial

A cycle of glacial and interglacial periods in the Quaternary caused species’ ranges to expand and contract in response to climatic and environmental changes. During interglacial periods, many species expanded their distribution ranges from refugia into higher elevations and latitudes. In the present work, we projected the responses of the five lineages of Testudo graeca in the Middle East and Transcaucasia as the climate shifted from the Last Glacial Maximum (LGM, Mid – Holocene), to the present. Under the past LGM and Mid-Holocene bioclimatic conditions, models predicted relatively more suitable habitats for some of the lineages. The most significant bioclimatic variables in predicting the present and past potential distribution of clades are the precipitation of the warmest quarter for T. g. armeniaca (95.8 %), precipitation seasonality for T. g. buxtoni (85.0 %), minimum temperature of the coldest month for T. g. ibera (75.4 %), precipitation of the coldest quarter for T. g. terrestris (34.1 %), and the mean temperature of the driest quarter for T. g. zarudyni (88.8 %). Since the LGM, we hypothesise that the ranges of lineages have either expanded (T. g. ibera), contracted (T. g. zarudnyi) or remained stable (T. g. terrestris), and for other two taxa (T. g. armeniaca and T. g. buxtoni) the pattern remains unclear. Our analysis predicts multiple refugia for Testudo during the LGM and supports previous hypotheses about high lineage richness in Anatolia resulting from secondary contact.

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