South Atlantic interocean exchange as the trigger for the Bøolling warm event
Journal
Geology
Journal Volume
36
Journal Issue
12
Pages
919-922
Date Issued
2008
Author(s)
Abstract
The North Atlantic Ocean underwent an abrupt temperature increase of 9 °C at high latitudes within a couple of decades during the transition from Heinrich event 1 (H1) to the Bølling warm event, but the mechanism responsible for this warming remains uncertain. Here we address this issue, presenting high-resolution last deglaciation planktic and benthic forami niferal records of temperature and oxygen isotopic composition of seawater (δ18Osw) for the subtropical South Atlantic. We identify a warming of ∼6.5 °C and an increase in 18Osw of 1.2 °C at the permanent thermocline during the transition, and a simultaneous warming of ∼3.5 °C with no significant change in δ 18Osw at intermediate depths. Most of the warming can be explained by tilting the South Atlantic east-west isopycnals from a flattened toward a steepened position associated with a collapsed (H1) and strong (Bølling) Atlantic meridional overturning circulation (AMOC). However, this zonal seesaw explains an increase of just 0.3 in permanent thermocline δ18 Osw. Considering that δ18Osw at the South Atlantic permanent thermocline is strongly influenced by the inflow of salty Indian Ocean upper waters, we suggest that a strengthening in the Agulhas leakage took place at the transition from H1 to the Bølling, and was responsible for the change in δ18Osw recorded in our site. Our records highlight the important role played by Indian-Atlantic interocean exchange as the trigger for the resumption of the AMOC and the Bølling warm event. © 2009 The Geological Society of America.
SDGs
Other Subjects
Atlantic meridional overturning circulations; Deglaciations; Heinrich Events; High Latitudes; High resolution; Indian ocean; Intermediate depths; North Atlantic Ocean; Oxygen isotopic composition; South Atlantic; Temperature increase; Leakage (fluid); Oceanography; Oxygen; Seawater; Stream flow; Sulfur compounds; Uncertainty analysis; Bolling; deglaciation; geological record; Heinrich event; overturn; oxygen isotope; paleoceanography; paleotemperature; seawater; thermocline; warming; water exchange; Atlantic Ocean; Atlantic Ocean (North); Indian Ocean
Type
journal article