Open AccessImpact of abrupt climate change in the tropical southeast Atlantic during Marine Isotope Stage (MIS) 3
Author(s) -
Hessler Ines,
Steinke Stephan,
Groeneveld Jeroen,
Dupont Lydie,
Wefer Gerold
Publication year - 2011
Publication title -
paleoceanography
Language(s) - English
Resource type - Journals
eISSN - 1944-9186
pISSN - 0883-8305
DOI - 10.1029/2011pa002118
Subject(s) - upwelling , oceanography , marine isotope stage , geology , stadial , teleconnection , globigerinoides , sea surface temperature , northern hemisphere , globigerina bulloides , foraminifera , climatology , ocean gyre , tropical atlantic , glacial period , north atlantic deep water , southern hemisphere , atlantic multidecadal oscillation , thermohaline circulation , benthic zone , interglacial , subtropics , holocene , paleontology , el niño southern oscillation , fishery , biology
High resolution planktonic foraminifera Mg/Ca paleotemperatures and oxygen isotopes of seawater of Ocean Drilling Program (ODP) Site 1078 (off Angola) have been reconstructed and reveal insights into the seasonal thermal evolution of the Angola Current (AC), the Angola‐Benguela Front (ABF), and the Benguela Current (BC) during the last glacial (50–23.5 ka BP). Special emphasis is put on time intervals possibly associated with the North Atlantic Heinrich Stadials (HS), which are thought to lead to an accumulation of heat in the South Atlantic due to a reduction of the Atlantic Meridional Overturning Circulation (AMOC). Within dating uncertainties, Globigerinoides ruber (pink) Mg/Ca‐based sea surface temperature (SST) estimates that represent southern hemisphere summer surface conditions show several warming episodes that coincide with North Atlantic HS, thus supporting the concept of the bipolar thermal seesaw. In contrast, the Mg/Ca‐based temperatures of Globigerina bulloides , representing the SST of the ABF/BC system during southern hemisphere winter, show no obvious response to the North Atlantic HS in the study area. We suggest that surface water cooling during the winter season is due to enhanced upwelling or upwelling of colder water masses which has most likely mitigated a warming of the ABF/BC system during HS. We further speculate that the seasonal asymmetry in our SST record results from seasonal differences in the dominance of atmospheric and oceanic teleconnections during periods of northern high latitude cooling.