Assessing the Ability of Zonal δ¹⁸O Contrast in Benthic Foraminifera to Reconstruct Deglacial Evolution of Atlantic Meridional Overturning Circulation

δ¹⁸O in foraminifera (δ¹⁸O_c) is a useful proxy for density, and the strength of the Atlantic Meridional Overturning Circulation (AMOC) can be reconstructed by the zonal density contrast in the Atlantic. However, whether the deglacial zonal δ¹⁸O_c contrast can represent the AMOC change is still unclear. δ¹⁸O_c contrast across the Florida Straits has been hypothesized as a proxy for the AMOC evolution during the last deglaciation, but the strength of Florida Current could also be influenced by wind forcing. Here we examine the ability of the zonal δ¹⁸O_c contrast to reconstruct AMOC in a deglacial model simulation. The model simulation suggests that the deglacial variation of the Florida Current strength is dominated by AMOC, with the wind effect on the variation of the Florida Current being negligible. Furthermore, the δ¹⁸O_c contrast across the western boundary along the entire Atlantic and the basin-wide δ¹⁸O_c contrast in the North Atlantic in the upper ocean can also be used to reconstruct AMOC. However, using basin-wide δ¹⁸O_c contrast to reconstruct AMOC in the South Atlantic is not possible at all water depths. In the subtropical South Atlantic, the basin-wide δ¹⁸O_c contrast is decoupled from the density contrast between 400 to 600 m through the deglaciation because of the deglacial change of the Antarctic Intermediate Water. Therefore, δ¹⁸O_c is a useful proxy to reconstruct past density and in turn past AMOC, but caution has to be used when using the basin-wide δ¹⁸O_c contrast to reconstruct the basin-wide density contrast in the South Atlantic.