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| Titel |
High-resolution leaf wax carbon and hydrogen isotopic record of the late Holocene paleoclimate in arid Central Asia |
| VerfasserIn |
B. Aichner, S. J. Feakins, J. E. Lee, U. Herzschuh, X. Liu |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1814-9324
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| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 11, no. 4 ; Nr. 11, no. 4 (2015-04-01), S.619-633 |
| Datensatznummer |
250117255
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| Publikation (Nr.) |
 copernicus.org/cp-11-619-2015.pdf |
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| Zusammenfassung |
| Central Asia is located at the confluence of large-scale atmospheric
circulation systems. It is thus likely to be highly susceptible to changes
in the dynamics of those systems; however, little is still known about the
regional paleoclimate history. Here we present carbon and hydrogen isotopic
compositions of n-alkanoic acids from a late Holocene sediment core from Lake
Karakuli (eastern Pamir, Xinjiang Province, China). Instrumental evidence
and isotope-enabled climate model experiments with the Laboratoire de
Météorologie Dynamique Zoom model version 4 (LMDZ4) demonstrate that
δ D values of precipitation in the region are influenced by both
temperature and precipitation amount. We find that these parameters are
inversely correlated on an annual scale, i.e., the climate has varied between relatively
cool and wet and more warm and dry over the last 50 years. Since the isotopic signals of
these changes are in the same direction and therefore additive, isotopes in
precipitation are sensitive recorders of climatic changes in the region.
Additionally, we infer that plants use year-round precipitation
(including snowmelt), and thus leaf wax δ D values must also respond to shifts in
the proportion of moisture derived from westerly storms during late
winter and early spring. Downcore results give evidence for a gradual shift to
cooler and wetter climates between 3.5 and 2.5 cal kyr BP, interrupted by a
warm and dry episode between 3.0 and 2.7 kyr BP. Further cool and wet episodes
occur between 1.9 and 1.5 and between 0.6 and 0.1 kyr BP, the latter coeval
with the Little Ice Age. Warm and dry episodes from 2.5 to 1.9 and
1.5 to 0.6 kyr BP coincide with the Roman Warm Period and Medieval Climate
Anomaly, respectively. Finally, we find a drying tend in recent decades.
Regional comparisons lead us to infer that the strength and position of the
westerlies, and wider northern hemispheric climate dynamics, control climatic
shifts in arid Central Asia, leading to complex local responses. Our new
archive from Lake Karakuli provides a detailed record of the local
signatures of these climate transitions in the eastern Pamir. |
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