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Title: Meltwater routing and the Younger Dryas

Abstract

The Younger Dryas -- the last major cold episode on Earth -- is generally considered to have been triggered by a meltwater flood into the North Atlantic. The prevailing hypothesis, proposed by Broecker et al. [1989 Nature 341:318–321] more than two decades ago, suggests that an abrupt rerouting of Lake Agassiz overflow through the Great Lakes and St. Lawrence Valley inhibited deep water formation in the subpolar North Atlantic and weakened the strength of the Atlantic Meridional Overturning Circulation (AMOC).More recently, Tarasov and Peltier [2005 Nature 435:662–665] showed that meltwater could have discharged into the Arctic Ocean via the Mackenzie Valley ~4,000 km northwest of the St. Lawrence outlet. Here we use a sophisticated, high-resolution, ocean sea-ice model to study the delivery of meltwater from the two drainage outlets to the deep water formation regions in the North Atlantic. Unlike the hypothesis of Broecker et al., freshwater from the St. Lawrence Valley advects into the subtropical gyre ~3,000 km south of the North Atlantic deep water formation regions and weakens the AMOC by <15%. In contrast, narrow coastal boundary currents efficiently deliver meltwater from the Mackenzie Valley to the deep water formation regions of the subpolar North Atlantic and weakenmore » the AMOC by >30%. We conclude that meltwater discharge from the Arctic, rather than the St. Lawrence Valley, was more likely to have triggered the Younger Dryas cooling.« less

Authors:
 [1];  [2]
  1. Univ. of Massachusetts, Amherst, MA (United States). Dept. of Geosciences, Climate System Research Center
  2. Univ. of Alaska, Fairbanks, AK (United States). Inst. of Marine Science, School of Fisheries and Ocean Sciences
Publication Date:
Research Org.:
Univ. of Alaska, Fairbanks, AK (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1105906
Grant/Contract Number:  
FG02-09ER64725
Resource Type:
Accepted Manuscript
Journal Name:
Proceedings of the National Academy of Sciences of the United States of America
Additional Journal Information:
Journal Volume: 109; Journal Issue: 49; Journal ID: ISSN 0027-8424
Publisher:
National Academy of Sciences, Washington, DC (United States)
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES

Citation Formats

Condron, Alan, and Winsor, Peter. Meltwater routing and the Younger Dryas. United States: N. p., 2012. Web. doi:10.1073/pnas.1207381109.
Condron, Alan, & Winsor, Peter. Meltwater routing and the Younger Dryas. United States. doi:10.1073/pnas.1207381109.
Condron, Alan, and Winsor, Peter. Tue . "Meltwater routing and the Younger Dryas". United States. doi:10.1073/pnas.1207381109. https://www.osti.gov/servlets/purl/1105906.
@article{osti_1105906,
title = {Meltwater routing and the Younger Dryas},
author = {Condron, Alan and Winsor, Peter},
abstractNote = {The Younger Dryas -- the last major cold episode on Earth -- is generally considered to have been triggered by a meltwater flood into the North Atlantic. The prevailing hypothesis, proposed by Broecker et al. [1989 Nature 341:318–321] more than two decades ago, suggests that an abrupt rerouting of Lake Agassiz overflow through the Great Lakes and St. Lawrence Valley inhibited deep water formation in the subpolar North Atlantic and weakened the strength of the Atlantic Meridional Overturning Circulation (AMOC).More recently, Tarasov and Peltier [2005 Nature 435:662–665] showed that meltwater could have discharged into the Arctic Ocean via the Mackenzie Valley ~4,000 km northwest of the St. Lawrence outlet. Here we use a sophisticated, high-resolution, ocean sea-ice model to study the delivery of meltwater from the two drainage outlets to the deep water formation regions in the North Atlantic. Unlike the hypothesis of Broecker et al., freshwater from the St. Lawrence Valley advects into the subtropical gyre ~3,000 km south of the North Atlantic deep water formation regions and weakens the AMOC by <15%. In contrast, narrow coastal boundary currents efficiently deliver meltwater from the Mackenzie Valley to the deep water formation regions of the subpolar North Atlantic and weaken the AMOC by >30%. We conclude that meltwater discharge from the Arctic, rather than the St. Lawrence Valley, was more likely to have triggered the Younger Dryas cooling.},
doi = {10.1073/pnas.1207381109},
journal = {Proceedings of the National Academy of Sciences of the United States of America},
number = 49,
volume = 109,
place = {United States},
year = {2012},
month = {12}
}

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