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

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.

Keyword(s)

Dansgaard-Oeschger event, Heinrich event, abrupt climate change, marine sediment core, ice core, sea ice

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Pedro J.B., Andersson C., Vettoretti G., Voelker A.H.L., Waelbroeck C., Dokken T.M., Jensen M.F., Rasmussen S.O., Sessford E.G., Jochum M., Nisancioglu K.H. (2022). Dansgaard-Oeschger and Heinrich event temperature anomalies in the North Atlantic set by sea ice, frontal position and thermocline structure. Quaternary Science Reviews. 289. 107599 (16p.). https://doi.org/10.1016/j.quascirev.2022.107599, https://archimer.ifremer.fr/doc/00779/89088/

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