资源环境科技发展态势分析平台

Changes in ocean carbon inventory are considered the likely primary driver of declining glacial atmospheric pCO₂ through the Mid-Pleistocene Transition (MPT). Here, we present global core-top calibrations of the “size-normalized weight” (SNW) of planktonic foraminifera for estimating paleo-deep-water Δ[CO₃ ²⁻]. Then, we apply this approach to reconstruct deep-water Δ[CO₃ ²⁻] in the western tropical Pacific since ∼1.4 Ma. At ∼1.0-0.9 Ma, a rapid weakening of North Atlantic Deep Water (NADW) resulted in a transient increase of ∼10 μmol kg⁻¹ in deep-water Δ[CO₃ ²⁻], after which deep-water Δ[CO₃ ²⁻] declined at ∼0.9-0.7 Ma. Glacial and interglacial deep-water Δ[CO₃ ²⁻] reveals stepwise declines of about 7 and 10 μmol kg⁻¹, respectively, after MIS 20 (0.79-0.81 Ma) and MIS 19 (0.76-0.79 Ma), reflecting increased DIC content in the deep Pacific. We infer that a sustained increase in deep Pacific carbon storage following the MPT was linked to enhanced oceanic stratification and greater influence of CO₂-rich Southern Ocean-sourced waters.