Glacial Southern Ocean Expansion Recorded in Foraminifera‐Bound Nitrogen Isotopes From the Agulhas Plateau During the Mid‐Pleistocene Transition

Abstract

Around 1 million years ago (Ma), Antarctica and the Southern Ocean witnessed expansion of polar ice sheets and Southern Ocean sea ice (Starr et al., 2021) and increases in iron delivery and biological productivity in the Subantarctic Zone (SAZ) (Kemp et al., 2010;Martínez-García et al., 2009). Alongside evidence for increased deep ocean carbon storage (Farmer et al., 2019), these surface changes implicate a Southern Ocean driver in the extension and amplification of glacial-interglacial cycles from 40 to ∼100 Kyr pacing during the Mid-Pleistocene