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| Titel |
The effect of sudden ice sheet melt on ocean circulation and surface climate
14-16 ka |
| VerfasserIn |
Ruza Ivanovic, Lauren Gregoire, Andrew Wickert, Paul Valdes |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250122963
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| Publikation (Nr.) |
 EGU/EGU2016-2118.pdf |
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| Zusammenfassung |
| Collapse of ice sheets can cause significant sea-level rise and widespread climate change.
Around 14.6 thousand years ago, global sea level rose by ∼15 m in less than 350 years[1]
during an event known as Meltwater Pulse 1a. Modelling work[2,3] has suggested that
approximately half of this ∼50 mm yr−1 sea level rise came from a North American ice
Saddle Collapse that drained into the Arctic and Atlantic Oceans. However, dating
uncertainties make it difficult to determine the sequence of events and their drivers, leaving
many fundamental questions. For example, did the abrupt ice melting and subsequent ocean
freshening have any detectable climatic impact? Was melting from the Northern
American ice sheets responsible for the Older-Dryas[4] or other cooling events?
And how were all these signals linked to changes in Atlantic Ocean overturning
circulation[e.g.5]?
To address these questions, we examined the effect of the North American ice Saddle
Collapse using a newly developed high resolution network drainage model coupled to an
atmosphere-ocean-vegetation General Circulation Model. Here, we present the first
quantitative routing estimates of the consequent meltwater discharge and its impact on
climate.
The results show that approximately 50% of the Saddle Collapse meltwater pulse was
routed down the Mackenzie River into the Arctic Ocean, and around half was discharged
directly into the Atlantic via the St. Lawrence River. This meltwater flux, equivalent to a total
of 7 m of sea-level rise, caused a strong weakening of Atlantic Meridional Overturning
Circulation (AMOC) and widespread Northern Hemisphere cooling. The greatest cooling is
in the Arctic, but there is also significant warming over North America. We find
that AMOC (and climate) is most sensitive to meltwater discharged to the Arctic
Ocean.
[1] Deschamps et al. (2012) Nature 483, 559–564. [2] Gregoire et al. (2012) Nature 487,
219–222. [3] Gomez et al. (2015) GRL 42(10), 3954-3962. [4] Menviel et al. (2010) QSR 30,
9-10. [5] Roberts et al. (2010) Science 327, 75–78. |
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