IPICS International Partnerships in Ice Core Sciences

KEYNOTE: Dansgaard-Oeschger and Heinrich event temperature anomalies in the North Atlantic: follow the heat

3 Oct 2022, 08:30

30m

Oral presentation Rapid changes and teleconnections

Speaker

Joel Pedro (Australian Antarctic Division; Kingston; Tasmania & Australia Australian Antarctic Program Partnership; Institute for Marine and Antarctic Studies; University of Tasmania; Hobart; Tasmania; Australia. )

Description

Here, using eighteen timescale-synchronised near-surface temperature reconstructions spanning 10–50 thousand years before present, we clarify the spatial extent and amplitude of Dansgaard-Oeschger (D-O) and Heinrich (H) event temperature anomalies in the North Atlantic. The North Atlantic Drift region shows D-O temperature variations (of ca. 2–5°C) with Greenland-like structure. The Western Iberian Margin region also shows D-O temperature variations with Greenland-like structure, but with much greater 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. The spatial pattern and amplitude of these D-O and H event temperature anomalies are matched remarkably closely in results from a new global climate model simulation that features spontaneous (D-O-like) and fresh-water forced (H-like) abrupt climate changes. We use the model and observations to show how 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. Our results support the view that D-O events are part of an oscillatory climate mode that is not reliant on a systematic trigger.