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Abstract Accurate reconstructions of export production in the Subantarctic Zone of the Southern Ocean are crucial for understanding the carbon cycle during Earth's past. However, due to the strong bottom water circulation of the Antarctic Circumpolar Current, sediment redistribution complicates age‐model‐derived bulk mass accumulation rates (BMAR). Here, we assess export production and its drivers over the past ∼1.4 Myr near the Drake Passage entrance using BMAR of biogenic barium, organic carbon, biogenic opal, calcium carbonate, and iron from sediment core PS97/093‐2, all of which are corrected for lateral sediment redistribution (corr‐BMAR). To quantify this correction, we explore the relationship between sortable silt as a bottom current strength proxy and²³⁰Th‐derived focusing factors as indicators of lateral redistribution of sediments, respectively. Our findings highlight peak Fe input prior and during glacials of the Mid‐Pleistocene Transition (MPT), likely driven by enhanced Patagonian weathering. The carbonate record indicates increased deep‐ocean corrosivity after around 1 Ma ago and displays a shift in the accumulation pattern post‐MPT, with only isolated peaks in some peak interglacials. The high carbonate values during MIS 11 likely relate toGephyrocapsacoccolithophore propagation, preceded and followed by prolonged carbonate dissolution periods, possibly linked to the Mid‐Brunhes Event. After the MPT, productivity proxies respond to glacial and interglacial intensity, with maxima found during MIS 16, MIS 11, MIS 5, and the Holocene, while minima occur during MIS 15–12. Our findings offer insights into long‐term productivity dynamics and their relationship to important climatic events over the past 1.4 Myr. 

Abstract As the last time period when concentrations were near 400 ppm, the Pliocene Epoch (5.33–2.58 Ma) is a useful paleoclimate target for understanding future climate change. Existing estimates of global warming and climate sensitivity during the Pliocene rely mainly on model simulations. To reconstruct Pliocene climate and incorporate paleoclimate observations, we use data assimilation to blend sea‐surface temperature (SST) proxies with model simulations from the Pliocene Modeling Intercomparison Project 2 and the Community Earth System Models. The resulting reconstruction, “plioDA,” suggests that the mid‐Pliocene (3.25 Ma) was warmer than previously thought (on average 4.1°C warmer than preindustrial, 95% CI = 3.0°C–5.3°C), leading to a higher estimate of climate sensitivity (4.8°C per doubling of , 90% CI = 2.6°C–9.9°C). In agreement with previous work, the tropical Pacific zonal SST gradient during the mid‐Pliocene was moderately reduced (°C, 95% CI = –0.4°C). However, this gradient was more reduced during the early Pliocene (4.75 Ma, °C, 95% CI = –°C), a time period that is also warmer than the mid‐Pliocene (4.8°C above preindustrial, 95% CI = 3.6°C–6.2°C). PlioDA reconstructs a fresh North Pacific and salty North Atlantic, supporting Arctic gateway closure and contradicting the presence of Pacific Deep Water formation. Overall, plioDA updates our view of global and spatial climate change during the Pliocene, as well as raising questions about the state of ocean circulation and the drivers of differences between the early and mid‐Pliocene.