Timing of iceberg scours and massive ice-rafting events in the subtropical North Atlantic

• Published in: Nature Communications
• Main Authors: Condron, Alan, Hill, Jenna C.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Nature Research 2021
• Subjects: National Science Foundation Office of Polar Programs; North Atlantic
• Online Access: https://hdl.handle.net/1912/27579

© The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Condron, A., & Hill, J. C. Timing of iceberg scours and massive ice-rafting events in the subtropical North Atlantic. Nature Communications, 12(1), (2021): 3668, https://doi.org/10.1038/s41467-021-23924-0. High resolution seafloor mapping shows extraordinary evidence that massive (>300 m thick) icebergs once drifted >5,000 km south along the eastern United States, with >700 iceberg scours now identified south of Cape Hatteras. Here we report on sediment cores collected from several buried scours that show multiple plow marks align with Heinrich Event 3 (H3), ~31,000 years ago. Numerical glacial iceberg simulations indicate that the transport of icebergs to these sites occurs during massive, but short-lived, periods of elevated meltwater discharge. Transport of icebergs to the subtropics, away from deep water formation sites, may explain why H3 was associated with only a modest increase in ice-rafting across the subpolar North Atlantic, and implies a complex relationship between freshwater forcing and climate change. Stratigraphy from subbottom data across the scour marks shows there are additional features that are both older and younger, and may align with other periods of elevated meltwater discharge. A.C.’s research was supported by the National Science Foundation Office of Polar Programs through NSF grant OCE-1903427 and the Biological and Environmental Research (BER) division of the US Department of Energy through grant DE-SC0019263. The numerical simulations were carried out using MITgcm on the Woods Hole Oceanographic Institution HPC machine, Poseidon. J.H.’s research was supported by the National Science Foundation Marine Geology and Geophysics Program through NSF grant 1558994 and by the US Geological Survey Coastal and Marine Hazards and Resources Program.