Contamination of 8.2 ka cold climate records by the Storegga tsunami in the Nordic Seas

• Published in: Nature communications Vol. 15; no. 1; p. 2904
• Main Authors: Bondevik, Stein, Risebrobakken, Bjørg, Gibbons, Steven J., Rasmussen, Tine L., Løvholt, Finn
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 04-04-2024; Nature Publishing Group; Springer Nature; Nature Portfolio
• Subjects: 704/106/413; 704/4111; 704/829; Cold; Contamination; Cooling; Flow velocity; Humanities and Social Sciences; Isotopes; Landslides; multidisciplinary; Ocean floor; Oxygen isotopes; Science; Science (multidisciplinary); Sea currents; Sediments; Tsunamis; Water depth
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-024-47347-9

The 8200-year BP cooling event is reconstructed in part from sediments in the Norwegian and North Seas. Here we show that these sediments have been reworked by the Storegga tsunami – dated to the coldest decades of the 8.2 ka event. We simulate the maximum tsunami flow velocity to be 2–5 m/s on the shelf offshore western Norway and in the shallower North Sea, and up to about 1 m/s down to a water depth of 1000 m. We re-investigate sediment core MD95-2011 and found the cold-water foraminifera in the 8.2 ka layer to be re-deposited and 11,000 years of age. Oxygen isotopes of the recycled foraminifera might have led to an interpretation of a too large and dramatic climate cooling. Our simulations imply that large parts of the sea floor in the Norwegian and North Seas probably were reworked by currents during the Storegga tsunami.
Tsunamis can disturb sea floor sediments. This study shows that climate records of the famous 8200-year-old cold spell inferred from Norwegian Sea sediments are likely contaminated by tsunami waves from the giant Storegga Landslide.