Increased Drake Passage through-flow triggered abrupt re-invigoration of Atlantic Overturning Circulation during the last deglaciation
Abstract
The position of Antarctic Circumpolar Current (ACC) fronts in the Drake Passage is important for the supply of low-density intermediate water into the Atlantic, and is thus key to the stability of Atlantic Meridional Overturning Circulation (AMOC). We examined changes in the position of ACC fronts by reconstructing flow speed and temperature in the Drake Passage over the last 25,000 years. A dramatic convergence of flow speeds and temperatures at the entrance and exit of Drake Passage 14,700 years ago indicates a significant southward shift of the sub-Antarctic Front from a position north of Drake Passage. The timing of this southward shift coincides with an abrupt re-invigoration of AMOC at the onset of the Bølling-Allerød. We argue that 14,700 years ago, a southward shift in the position of the ACC fronts relative to Drake Passage enabled low-density intermediate water to enter the Atlantic; this accentuated the meridional density gradient in the Atlantic causing an abrupt re-invigoration of AMOC.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFMPP13C..06R
- Keywords:
-
- 1605 Abrupt/rapid climate change;
- GLOBAL CHANGEDE: 1616 Climate variability;
- GLOBAL CHANGEDE: 1620 Climate dynamics;
- GLOBAL CHANGEDE: 4901 Abrupt/rapid climate change;
- PALEOCEANOGRAPHY