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| Titel |
Abrupt drying events in the Caribbean related to large Laurentide meltwater pulses during the glacial-to-Holocene transition |
| VerfasserIn |
Rolf Vieten, Sophie Warken, Amos Winter, Denis Scholz, David Black, Davide Zanchettin, Thomas E. Miller |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250138438
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| Publikation (Nr.) |
 EGU/EGU2017-1450.pdf |
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| Zusammenfassung |
| At the end of the last deglaciation North Atlantic meltwater pulses from the retreating
Laurentide ice sheet triggered a chain of oceanic and atmospheric responses including
temporary slow-down of the thermohaline circulation and hemispheric-scale alterations of the
atmospheric circulation. The 8.2 ka event (occurring about 8.2 ka BP) is the most pronounced
meltwater pulse during the Holocene and serves as an analogue to understand how North
Atlantic fresh water influxes can affect the ocean-atmosphere coupled system on a basin,
hemispheric or global scale. This event left strong regional climate imprints, such as abrupt
cooling reconstructed over the North Atlantic and Europe lasting 100 to 150 years
and drying in the northern hemispheric tropics. However, there is a lack of high
resolution proxies to learn about the event’s temporal structure especially in the
tropics.
We present geochemical evidence from a stalagmite indicating sudden climate
fluctuations towards drier conditions in the northeastern Caribbean possibly related to rapid
cooling in the high northern latitudes and a southward shift of the Inter-Tropical Convergence
Zone (ITCZ). Stalagmite PR-PA-1 was collected in Palco cave, Puerto Rico, and it is a
remarkable record of the 8.2 ka event because 15 MC-ICPMS 230Th/U-dates produce a
precise chronology of its Holocene period growing solely between 9.0 ka BP to 7.5 ka BP.
Based on 240 trace element and stable isotope ratio measurement we reconstructed
hydrological changes with sub-decadal resolution. Our proxy data show large and rapid
climate variations before 8.0 ka. Pronounced peaks in the Mg/Ca and δ13C records indicate
three major events of abrupt drying. These fluctuations towards drier conditions took place in
less than 10 years and the climate remained drier than the natural range for 10 to 20 years,
before it returned to pre-fluctuation conditions again. Our observations confirm
previous studies suggesting that repeated meltwater pulses affected the thermohaline
circulation leading to the temporal and spatial extension of the 8.2 ka event. Moreover,
based on our results we hypothesize that three large meltwater pulses decreased the
thermohaline circulation, cooled the North Atlantic region and pushed the region of ITCZ
influence further southward leading to decreased rainfall in the northeastern Caribbean. |
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