Status: this preprint is open for discussion and under review for Climate of the Past (CP).
Atlantic water intrusions onto the Scotian Shelf during the past 8.6 ka BP
Henriette M. Kolling,Markus Kienast,Peter Matzerath,Julia Gottschalk,Stephanie Kienast,Daniel A. Frick,Felix Gross,Jack Wharton,David Thornalley,and Ralph R. Schneider
Editorial note: the leadership of Climate of the Past has been alerted that the authors of the paper "Atlantic Water Intrusions onto the Scotian Shelf during the Past 8.6 ka BP" are making extensive use of unpublished data and ideas from a student's PhD thesis. Although the authors correctly cite the thesis in numerous places to support new ideas, they are presenting these ideas for the first time. Kolling et al. as preprint authors, the former PhD student, their supervisor, the Climate of the Past leadership, the handling editor, and Copernicus have decided that the manuscript currently under assessment should be edited to include the PhD student and their supervisor as co-authors. Jack Wharton and David Thornalley were added as co-authors on 25 February 2026.
Abstract. The Scotian Shelf lies at the confluence of warm Gulf Stream (GS) waters and the cold Labrador Current (LC), making it highly sensitive to large- and small-scale climate variability. Modern observations show rapid regional warming accelerated by episodic GS-derived intrusions, yet Holocene paleoceanographic reconstructions from this margin are sparse and often conflicting with respect to the frequency and extent of intrusion events. Here, we present high-resolution Mg/Ca-derived sea-surface temperature (SST) and planktonic δ¹⁸O records from St. Anns Basin on the north-eastern Scotian Shelf that provide new insights into the hydrographic surface-ocean variability of the past 8.5 ka calibrated Before Present (cal BP). While the SST record does not capture the 8.2 ka event, this event is evident in the δ¹⁸O and Ca/Sr records, indicating that its freshwater signal reached the Scotian Shelf. Reconstructed SSTs are generally cold from ~8.5 to ~6.2 cal ka BP, followed by a gradual increase in mean SSTs punctuated by multiple short-lived warm and saline events beginning around 6 cal ka BP, at 6.0–5.8, 5.5–5.4, 5.1–4.9, 3.2–3.1, 2.5–2.2 and 1.05–0.8 cal ka BP, which we interpret as intrusions of GS-sourced slope waters. We attribute these events to basin-scale reorganizations of the GS-LC system, consistent with the minimum/maximum modal state framework of Pickart et al. (1999). Minimum modal state circulation, characterized by a strong onshore LC and an intensified Deep Western Boundary Current (DWBC), which is dominated by Denmark Strait Overflow water, creates a sharp front which restricts intrusions of warm water onto the Scotian Shelf. Maximum modal state conditions feature a weakened LC and increased Labrador Sea Water (LSW) contribution to the DWBC, and reduce cross-slope temperature and salinity gradients that permit GS-derived waters to penetrate the shelf. Overall, our results indicate that warm-water intrusions occurred regularly throughout the past 6.5 ka BP with magnitudes of 6.7 °C and 1.5 psu comparable to those observed today.
Received: 10 Feb 2026 – Discussion started: 17 Feb 2026
Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this paper. While Copernicus Publications makes every effort to include appropriate place names, the final responsibility lies with the authors. Views expressed in the text are those of the authors and do not necessarily reflect the views of the publisher.
Henriette M. Kolling,Markus Kienast,Peter Matzerath,Julia Gottschalk,Stephanie Kienast,Daniel A. Frick,Felix Gross,Jack Wharton,David Thornalley,and Ralph R. Schneider
Editorial note: the leadership of Climate of the Past has been alerted that the authors of the paper "Atlantic Water Intrusions onto the Scotian Shelf during the Past 8.6 ka BP" are making extensive use of unpublished data and ideas from a student's PhD thesis. Although the authors correctly cite the thesis in numerous places to support new ideas, they are presenting these ideas for the first time. Kolling et al. as preprint authors, the former PhD student, their supervisor, the Climate of the Past leadership, the handling editor, and Copernicus have decided that the manuscript currently under assessment should be edited to include the PhD student and their supervisor as co-authors. Jack Wharton and David Thornalley were added as co-authors on 25 February 2026.
Status: open (until 14 Apr 2026)
Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor
| : Report abuse
Henriette M. Kolling,Markus Kienast,Peter Matzerath,Julia Gottschalk,Stephanie Kienast,Daniel A. Frick,Felix Gross,Jack Wharton,David Thornalley,and Ralph R. Schneider
Editorial note: the leadership of Climate of the Past has been alerted that the authors of the paper "Atlantic Water Intrusions onto the Scotian Shelf during the Past 8.6 ka BP" are making extensive use of unpublished data and ideas from a student's PhD thesis. Although the authors correctly cite the thesis in numerous places to support new ideas, they are presenting these ideas for the first time. Kolling et al. as preprint authors, the former PhD student, their supervisor, the Climate of the Past leadership, the handling editor, and Copernicus have decided that the manuscript currently under assessment should be edited to include the PhD student and their supervisor as co-authors. Jack Wharton and David Thornalley were added as co-authors on 25 February 2026.
Henriette M. Kolling,Markus Kienast,Peter Matzerath,Julia Gottschalk,Stephanie Kienast,Daniel A. Frick,Felix Gross,Jack Wharton,David Thornalley,and Ralph R. Schneider
Editorial note: the leadership of Climate of the Past has been alerted that the authors of the paper "Atlantic Water Intrusions onto the Scotian Shelf during the Past 8.6 ka BP" are making extensive use of unpublished data and ideas from a student's PhD thesis. Although the authors correctly cite the thesis in numerous places to support new ideas, they are presenting these ideas for the first time. Kolling et al. as preprint authors, the former PhD student, their supervisor, the Climate of the Past leadership, the handling editor, and Copernicus have decided that the manuscript currently under assessment should be edited to include the PhD student and their supervisor as co-authors. Jack Wharton and David Thornalley were added as co-authors on 25 February 2026.
Viewed
Total article views: 190 (including HTML, PDF, and XML)
HTML
PDF
XML
Total
BibTeX
EndNote
123
55
12
190
7
13
HTML: 123
PDF: 55
XML: 12
Total: 190
BibTeX: 7
EndNote: 13
Views and downloads (calculated since 17 Feb 2026)
Cumulative views and downloads
(calculated since 17 Feb 2026)
Viewed (geographical distribution)
Total article views: 195 (including HTML, PDF, and XML)
Thereof 195 with geography defined
and 0 with unknown origin.
We studied past ocean conditions on the Scotian Shelf to understand how warm Gulf Stream waters reached this region in the past. Using chemical signals preserved in microscopic shells from seafloor sediments, we reconstructed sea surface temperature and salinity over the last 8,500 years. We found repeated warm-water intrusions during the mid to late Holocene, similar in strength to those observed today, providing important context for modern ocean warming.
We studied past ocean conditions on the Scotian Shelf to understand how warm Gulf Stream waters...
