TY  - JOUR
A1  - Lechleitner, Franziska A.
A1  - Breitenbach, Sebastian Franz Martin
A1  - Cheng, Hai
A1  - Plessen, Birgit
A1  - Rehfeld, Kira
A1  - Goswami, Bedartha
A1  - Marwan, Norbert
A1  - Eroglu, Deniz
A1  - Adkins, Jess F.
A1  - Haug, Gerald
T1  - Climatic and in-cave influences on delta O-18 and delta C-13 in a stalagmite from northeastern India through the last deglaciation
JF  - Quaternary research : an interdisciplinary journal
N2  - Northeastern (NE) India experiences extraordinarily pronounced seasonal climate, governed by the Indian summer monsoon (ISM). The vulnerability of this region to floods and droughts calls for detailed and highly resolved paleoclimate reconstructions to assess the recurrence rate and driving factors of ISM changes. We use stable oxygen and carbon isotope ratios (delta O-18 and delta C-13) from stalagmite MAW-6 from Mawmluh Cave to infer climate and environmental conditions in NE India over the last deglaciation (16-6ka). We interpret stalagmite delta O-18 as reflecting ISM strength, whereas delta C-13 appears to be driven by local hydroclimate conditions. Pronounced shifts in ISM strength over the deglaciation are apparent from the delta O-18 record, similarly to other records from monsoonal Asia. The ISM is weaker during the late glacial (LG) period and the Younger Dryas, and stronger during the BOlling-Allerod and Holocene. Local conditions inferred from the delta C-13 record appear to have changed less substantially over time, possibly related to the masking effect of changing precipitation seasonality. Time series analysis of the delta O-18 record reveals more chaotic conditions during the late glacial and higher predictability during the Holocene, likely related to the strengthening of the seasonal recurrence of the ISM with the onset of the Holocene.
KW  - Indian Summer Monsoon
KW  - stalagmite
KW  - oxygen isotopes
KW  - carbon isotopes
KW  - deglaciation
Y1  - 2017
U6  - https://doi.org/10.1017/qua.2017.72
SN  - 0033-5894
SN  - 1096-0287
VL  - 88
SP  - 458
EP  - 471
PB  - Cambridge Univ. Press
CY  - New York
ER  - 
TY  - JOUR
A1  - Fohlmeister, Jens Bernd
A1  - Plessen, Birgit
A1  - Dudashvili, Alexey Sergeevich
A1  - Tjallingii, Rik
A1  - Wolff, Christian Michael
A1  - Gafurov, Abror
A1  - Cheng, Hai
T1  - Winter precipitation changes during the Medieval Climate Anomaly and the Little Ice Age in arid Central Asia
JF  - Quaternary science reviews : the international multidisciplinary research and review journal
N2  - The strength of the North Atlantic Oscillation (NAO) is considered to be the main driver of climate changes over the European and western Asian continents throughout the last millennium. For example, the predominantly warm Medieval Climate Anomaly (MCA) and the following cold period of the Little Ice Age (LIA) over Europe have been associated with long-lasting phases with a positive and negative NAO index. Its climatic imprint is especially pronounced in European winter seasons. However, little is known about the influence of NAO with respect to its eastern extent over the Eurasian continent. Here we present speleothem records (PC, 8180 and Sr/Ca) from the southern rim of Fergana Basin (Central Asia) revealing annually resolved past climate variations during the last millennium. The age control of the stalagmite relies on radiocarbon dating as large amounts of detrital material inhibit accurate 230Th dating. Present-day calcification of the stalagmite is most effective during spring when the cave atmosphere and elevated water supply by snow melting and high amount of spring precipitation provide optimal conditions. Seasonal precipitation variations cause changes of the stable isotope and Sr/ Ca compositions. The simultaneous changes in these geochemical proxies, however, give also evidence for fractionation processes in the cave. By disentangling both processes, we demonstrate that the amount of winter precipitation during the MCA was generally higher than during the LIA, which is in line with climatic changes linked to the NAO index but opposite to the higher mountain records of Central Asia. Several events of strongly reduced winter precipitation are observed during the LIA in Central Asia. These dry winter events can be related to phases of a strong negative NAO index and all results reveal that winter precipitation over the central Eurasian continent is tightly linked to atmospheric NAO modes by the westerly wind systems. (C) 2017 Elsevier Ltd. All rights reserved.
Y1  - 2017
U6  - https://doi.org/10.1016/j.quascirev.2017.10.026
SN  - 0277-3791
VL  - 178
SP  - 24
EP  - 36
PB  - Elsevier
CY  - Oxford
ER  -