Dansgaard-Oeschger and Heinrich event temperature anomalies in the North Atlantic set by sea ice, frontal position and thermocline structure
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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.
|Tidsskrift||Quaternary Science Reviews|
|Status||Udgivet - 1 aug. 2022|
This research was supported by the European Research Council under the European Community's Seventh Framework Programme ( FP7/2007–2013 )/ ERC grant agreement 610055 (the ice2ice project) and by the ChronoClimate project funded by the Carlsberg Foundation . A.V. acknowledges funding support from FCT - Foundation for Science and Technology through projects UIDB/04326/2020 and IF/01500/2014 . J.B.P acknowledges support from the Australian Government Department of Industry Science Energy and Resources , grant ASCI000002 . C.W. acknowledges support from the European Research Council grant ACCLIMATE/339108 . S.O.R. acknowledges support from the IceFlow project funded by the VILLUM Foundation . The authors thank ice2ice project colleagues and the many palaeoceanographers who made their data available. We are grateful to the anonymous reviewers for constructive comments that improved the manuscript.
© 2022 The Authors