资源环境科技发展态势分析平台

Carbon release from the North Pacific in glacial-interglacial cycles has been mainly linked to the North Pacific Intermediate Water (NPIW) formation and associated carbon/nutrient water upwelling and biological productivity changes. However, relationship between NPIW and atmospheric CO₂ change in the early interglacial remains unclear. Here we report a high-resolution sediment record of NPIW evolution based on paleo-redox changes in the Western North Pacific during the last 400 ka. Our proxy and model results reveal a delayed collapse of NPIW after the glacial termination was coeval with decreased salinity of intermediate water and increased net rainfall in the North Pacific. Such weakened NPIW formation in the North Pacific probably make a contribution to maintain high atmospheric CO₂ concentrations through weakened intermediate-to-deep ocean stratification and reduced subsurface biological pump net efficiency, countering the return to more stratified conditions in the Southern Ocean, which should drive down atmospheric CO₂ during the early interglacial.