Abstract The Mid-Pleistocene Transition (MPT) is characterised by cooling and lengthening
glacial cycles from 600–1200 ka, thought to be driven by reductions in glacial CO2 in
particular from~ 900 ka onwards. Reduced high latitude upwelling, a process that retains
CO2 within the deep ocean over glacials, could have aided drawdown but has so far not
been constrained in either hemisphere over the MPT. Here, we find that reduced nutrient
upwelling in the Bering Sea, and North Pacific Intermediate Water expansion, coincided with …