Orbital and millennial-scale upper ocean dynamics in the Pacific Southern Ocean since the Mid-Pleistocene Transition

From orbital (10 to 100 thousand years or kyr) to millennial (1 to 10 kyr) timescales, the Southern Ocean is thought to substantially modulate global climate and ocean variability by affecting global heat, salt, and nutrient distribution and the processes influencing storage and outgassing of atmospheric CO2. The millennial-scale variability remains underexplored, as little high-resolution records are available. This variability is unknown across the Mid-Pleistocene Transition (MPT), a period when Earth´s ice ages lengthened and intensified between ~1,250 and ~750 kyr ago (ka). We take advantage of the unique location of IODP Site U1539 in vicinity of the present subantarctic front. This location is characterised by unusual high sedimentation-rates (~10-50 cm/kyr), mainly because Site U1539 is reached by the northerly extended opal belt during glacials with high diatom deposition. This unique setting provides a high-resolution pelagic sediment archive in an area with strong oceanographic gradients. We reconstructed and present sea-surface temperature, primary productivity, opal content, and current strength over the past 1,400 ka at an unprecedented resolution.