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| Titel |
Investigating the impact of Lake Agassiz drainage routes on the 8.2 ka cold event with a climate model |
| VerfasserIn |
Y.-X. Li, H. Renssen, A. P. Wiersma, T. E. Törnqvist |
| 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 ; 5, no. 3 ; Nr. 5, no. 3 (2009-08-28), S.471-480 |
| Datensatznummer |
250002546
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| Publikation (Nr.) |
 copernicus.org/cp-5-471-2009.pdf |
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| Zusammenfassung |
| The 8.2 ka event is the most prominent abrupt climate change in the Holocene
and is often believed to result from catastrophic drainage of proglacial
lakes Agassiz and Ojibway (LAO) that routed through the Hudson Bay and the
Labrador Sea into the North Atlantic Ocean, and perturbed Atlantic
meridional overturning circulation (MOC). One key assumption of this
triggering mechanism is that the LAO freshwater drainage was dispersed over
the Labrador Sea. Recent data, however, show no evidence of lowered
δ18O values, indicative of low salinity, from the open Labrador Sea
around 8.2 ka. Instead, negative δ18O anomalies are found close
to the east coast of North America, extending as far south as Cape Hatteras,
North Carolina, suggesting that the freshwater drainage may have been
confined to a long stretch of continental shelf before fully mixing with
North Atlantic Ocean water. Here we conduct a sensitivity study that
examines the effects of a southerly drainage route on the 8.2 ka event with
the ECBilt-CLIO-VECODE model. Hosing experiments of four routing scenarios,
where freshwater was introduced to the Labrador Sea in the northerly route
and to three different locations along the southerly route, were performed
to investigate the routing effects on model responses. The modeling results
show that a southerly drainage route is possible but generally yields
reduced climatic consequences in comparison to those of a northerly route.
This finding implies that more freshwater would be required for a southerly
route than for a northerly route to produce the same climate anomaly. The
implicated large amount of LAO drainage for a southerly routing scenario is
in line with a recent geophysical modelling study of gravitational effects
on sea-level change associated with the 8.2 ka event, which suggests that
the volume of drainage might be larger than previously estimated. |
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