TY  - JOUR
A1  - Meier, Karl J. F.
A1  - Bahr, André
A1  - Chiessi, Cristiano Mazur
A1  - Albuquerque, Ana Luiza
A1  - Raddatz, Jacek
A1  - Friedrich, Oliver
T1  - Role of the tropical atlantic for the interhemispheric heat transport during the last deglaciation
T2  - Paleoceanography and paleoclimatology
N2  - Abstract
During the last deglaciation abrupt millennial-scale perturbations of the Atlantic Meridional Overturning Circulation massively altered the interhemispheric heat distribution affecting, for example, continental ice volume and hydroclimate. If and how the related cross-equatorial heat transport was controlled by the interplay between the southward-flowing Brazil Current (BC) and northward-flowing North Brazil Current (NBC) remains controversial. To assess the role of tropical heat transport during the last deglaciation, we obtained a high-resolution foraminiferal Mg/Ca-based sea surface temperature (SST) record from the BC domain at 21.5°S. The data reveal a yet undocumented warming of at least 4.6°C of the BC during Heinrich Stadial 1 at ∼16 ka indicating massive oceanic heat accumulation in the tropical South Atlantic. Simultaneously, a strongly diminished NBC prevented the release of this excess heat into the northern tropics. The observed magnitude of heat accumulation substantially exceeds numerical model simulations, stressing the need to further scrutinize atmospheric and oceanic heat transport during extreme climatic events.

Plain Language Summary
The Atlantic overturning circulation underwent abrupt millennial-scale perturbations. Such phases of sluggish oceanic circulation resulted in a substantial reduction of northward heat transport. As a consequence, substantial cooling occurred in the Northern Hemisphere and warming occurred in the Southern Hemisphere with severe effects on tropical precipitation. The distribution of heat within the western tropical Atlantic is accomplished by the southward-flowing BC and the northward-flowing NBC. By reconstructing SSTs for the interval between 20,000 and 10,000 yr before present, we assess the role of both currents in the interhemispheric heat transport during weak Atlantic overturning. We found that a sluggish overturning circulation resulted in anomalous southward heat transport by the BC in concert with a weak NBC, which lead to a yet undocumented warming of at least 4.6°C in the western tropical South Atlantic. This warming significantly exceeds reconstructions based on numerical simulations. This points to the need to further improve our understanding of changes in the cross-equatorial oceanic and atmospheric heat transport in response to rapid changes in ocean circulation, in particular as a significant weakening of the Atlantic overturning circulation is predicted in the wake of anthropogenic climate change.
KW  - Bipolar seesaw
KW  - Brazil Current
KW  - foraminiferal geochemistry
KW  - Heinrich Event 1
KW  - North Brazil Current
KW  - tropical South Atlantic
Y1  - 2021
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/61462
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-614620
SN  - 2572-4525
VL  - 36
IS  - 5, e2020PA004107
SP  - 1
EP  - 14
PB  - Wiley
CY  - Hoboken, NJ
ER  -