Dansgaard-Oeschger and Heinrich event temperature anomalies in the North Atlantic set by sea ice, frontal position and thermocline structure

J. B. Pedro (1, 2, 3) , C. Andersson (4) , G. Vettoretti (3) , A. H. L. Voelker (5, 6) , Claire Waelbroeck (7) , T. M. Dokken (8) , M. F. Jensen (8) , S. O. Rasmussen (3) , E. G. Sessford (8) , M. Jochum (3) , K. H. Nisancioglu (9, 10, 8)

1 AAD - Australian Antarctic Division
2 IMAS - Institute for Marine and Antarctic Studies [Hobart]
3 ITU - IT University of Copenhagen
4 NORCE Norwegian Research Center
5 IPMA - Instituto Português de Investigação do Mar e da Atmosfera
6 CCMAR - Centro de Ciências do Mar [Faro]
7 PROTEO - Processus et interactions de fine échelle océanique
8 UiB - Department of Earth Science [Bergen]
9 BCCR - Bjerknes Centre for Climate Research
10 Center for Earth Evolution and Dynamics, University of Oslo

We use eighteen timescale-synchronised near-surface temperature reconstructions spanning 10-50 thousand years before present to clarify the regional expression of Dansgaard-Oeschger (D-O) and Heinrich (H) events in the North Atlantic. The North Atlantic Drift region shows D-O temperature variations of ca. 2-5° with Greenland-like structure. The Western Iberian Margin region also shows Greenland-like structure, but with more pronounced surface cooling between interstadials and Heinrich stadials (ca. 6-9 °C) than between interstadials and non-Heinrich stadials (ca. 2-3 °C). The southern Nordic Seas show smaller D-O temperature anomalies (ca. 1-2 °C) that appear out of phase with Greenland. These spatial patterns are replicated in a new global climate model simulation that features unforced (D-O-like) and freshwater forced (H-like) abrupt climate changes. The model simulations and observations suggest consistently that the spatial expression and amplitude of D-O and H event temperature anomalies are dominated by coupled changes in the Atlantic Meridional Overturning, sea ice extent, polar front position and thermocline structure.

Keywords: Dansgaard-Oeschger event; Heinrich event; abrupt climate change; marine sediment core; ice core; sea ice

Domains: Sciences of the Universe [physics]; Sciences of the Universe [physics]; Earth Sciences

J. B. Pedro, C. Andersson, G. Vettoretti, A. H. L. Voelker, Claire Waelbroeck, et al.. Dansgaard-Oeschger and Heinrich event temperature anomalies in the North Atlantic set by sea ice, frontal position and thermocline structure. Quaternary Science Reviews, 2022, 289, ⟨10.1016/j.quascirev.2022.107599⟩. ⟨insu-03746437⟩