Hydrological variability in Florida Straits during Marine Isotope Stage 5 cold events

Modeling and proxy studies indicate that a reduction of Atlantic MeridionalOverturning Circulation (AMOC) strength profoundly impacts temperatures and salinitiesin the (sub)tropical Atlantic, especially on subsurface levels. While previous studiesfocused on prominent periods of AMOC reduction during the last deglaciation, we aim totest whether similar reconfigurations of the subtropical hydrography occurred during themoderate climatic alterations punctuating the last interglacial Marine Isotope Stage (MIS) 5.Here, we present temperature and salinity records from a Florida Straits core by combiningd18O and Mg/Ca analyses on surface (Globigerinoides ruber, white) and deep‐dwelling(Globorotalia crassaformis) foraminifera covering MIS 5 in high resolution. The datareveal increasing salinities at intermediate depths during interglacial cooling episodes,decoupled from relatively stable surface conditions. This probably indicates the spatialexpansion of saline subtropical gyre waters due to enhanced Ekman downwellingand might also point to a changed density structure and altered geostrophic balance inFlorida Straits. Notably, these oceanographic alterations are not consistently occurringduring periods of AMOC reduction. The data suggest that the expansion of gyre watersinto Florida Straits was impeded by the increasing influence of Antarctic IntermediateWater (AAIW) from MIS 5.5 to ∼107 kyr BP. Afterward, increasingly positive benthicd13C values imply a recession of AAIW, allowing the temporary expansion of gyre watersinto Florida Straits. We argue that the inferred transient subtropical salt accumulationand warm pool expansion might have played a pivotal role in reinvigorating meridionaloverturning and dampen the severity of interglacial cold phases.