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| Titel |
Temperature and precipitation reconstruction in correspondence to Dansgaard-Oeschger events and glacial terminations from Turkey |
| VerfasserIn |
Mona Stockhecke, Achim Bechtel, Francien Peterse, Marie-Eve Randlett, Carsten J. Schubert, Axel Timmermann |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250121715
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| Publikation (Nr.) |
 EGU/EGU2016-543.pdf |
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| Zusammenfassung |
| Lacustrine records from deep closed lakes, such as the 600,000 yr-old sedimentary
sequence from Lake Van (Turkey), can provide detailed insights into the mechanisms
of past environmental changes in the continental interior. The Lake Van record is
continues and has an excellent age control over the last 350 ka. Repetitive intervals of
annually-laminated sections are reflected in a sub-annual resolved color record. The
Lake Van color record documents lake-level rises for all Dansgaard-Oeschger (DO)
interstadials synchronous to the NGRIP δ18O record of Greenland ice reflecting
temperature increases. Comparison with model hindcasts from LOVECLIM experiments,
supports the notion that the lake-level increases during the warm interstadials is
caused by precipitation increases due to atmospheric changes as consequence of
AMOC increase during a paucity of ice-sheet calving events. Quaternary quantitative
temperature and precipitation changes in the Eastern Mediterranean are unknown over
the last 150 ka although it covers a critical time and area in human and mammal
evolution.
We quantified temperature and hydroclimate changes within a multi-proxy biomarker
study. Lipid biomarkers during several DO events from MIS 3 and over the last two
terminations were extracted at centennial resolution. Mean air temperatures (MAT) based on
down-core distributional changes in branched glycerol dialkyl glycerol tetraethers
(brGDGTs), indicate a 1.5-3˚ warming at stadial/interstadial transitions and 2-4˚ warming
for glacials/interglacial transitions. Simultaneous analysis of the leaf wax hydrogen isotopic
composition (δ2Hwax) result in a reconstruction of changes in the source water due to
variable precipitation/evaporation ratio. Isotopically 10 ‰ (20 ) lighter δD-values of
leaf-wax n-alkane C29 argue for a significantly increased humidity during the interstadials
(interglacials) compared to the stadials (glacials). Magnitudes of temperature and
precipitation changes at the DO-transitions and glacial terminations are also quantitatively in
line with temperature and precipitation anomalies over Turkey from LOVECLIM model
simulations. The abruptly changing water availability and highly variable climates are
alternative driving mechanism for megafaunal transition events to be considered next to the
effects of long-lasting glacial coldness or/and competitive factors (e.g. hunting pressure). |
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