Carbon isotope evidence for a northern source of deep water in the glacial western North Atlantic

• Published in: Proceedings of the National Academy of Sciences
• Main Authors: Keigwin, Lloyd D., Swift, Stephen A.
• Format: Text
• Language: English
• Published: National Academy of Sciences 2017
• Subjects: Physical Sciences; Labrador Sea; North Atlantic
• Online Access: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5358345/; http://www.ncbi.nlm.nih.gov/pubmed/28193884; https://doi.org/10.1073/pnas.1614693114

Understanding glacial ocean circulation is tied to understanding heat transport in the North Atlantic, growth and maintenance of ice sheets, and atmospheric CO2 content. The proxy data are sparse, but, for decades, it has been thought that the North Atlantic did not produce deep water during the Last Glacial Maximum, unlike today. New C isotope results from a core at 5 km in the western North Atlantic indicate a young, glacial deep water may have been formed in the surface Labrador Sea by freezing and brine rejection. These data call for a revised circulation scheme where southern source water centered at 4.2 km would have been sandwiched between glacial North Atlantic intermediate water and the new dense bottom water.