Scholarlink

<p>Glacial atmospheric <i>p</i>CO<sub>2</sub> declines significantly relative to interglacials, with the ocean serving as the primary sink for atmospheric carbon loss. Geological records indicate an increase in carbon storage in the glacial North Pacific, making it an important contributor to the <i>p</i>CO<sub>2</sub> decline. The climate-carbon cycle dynamics driving the increase in deep North Pacific carbon storage remain highly controversial; compared to the abundant data available for the North Atlantic, the research foundation is particularly weak. Based on paleoceanographic carbon cycle proxies from North Pacific sites, previous studies have proposed the “deep convection hypothesis”, suggesting that deep convection may have existed in the glacial North Pacific, enhancing surface nutrient utilization efficiency and thereby increasing deep carbon storage. However, existing research lacks a quantitative understanding of the formation conditions for glacial North Pacific deep convection, its carbon cycle dynamics, and its impact on atmospheric <i>p</i>CO<sub>2</sub>. To address the relationship between glacial North Pacific deep convection and air-sea carbon balance, here we employed a state-of-the-art ocean carbon cycle model to conduct a series of anti-hosing experiments in the North Pacific. We show that, with Southern Ocean processes held constant, the presence of deep convection in the glacial North Pacific would disrupt the North Pacific halocline structure, induce diapycnal mixing, and release carbon from the deep Pacific reservoir, thereby hindering oceanic carbon storage and ultimately attenuating the glacial decline in atmospheric <i>p</i>CO<sub>2</sub>—inconsistent with predictions of the “deep convection hypothesis”. Conversely, with the presence of intermediate-depth convection in the glacial North Pacific, redistribution of surface alkalinity and dissolved inorganic carbon concentrations can reduce the <i>p</i>CO<sub>2</sub> difference between the sea surface and atmosphere, making the North Pacific a carbon sink, aligning with geological records. Further comparisons between numerical simulations and records highlight the complexity of glacial North Pacific carbon cycle processes, necessitating improvements to North Pacific salinity flux schemes in future numerical simulations, while incorporating paleoenvironmental records and taking into account the location, intensity, and depth of possible convection processes.</p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Deep convection in the glacial Pacific can hinder oceanic carbon sequestration: An ocean-biogeochemical model study

  • 期刊论文

  • 发表日期：

    2026年2月6日

查看全文
  • Jinlong Du,
  • Jun Tian

摘要

Glacial atmospheric pCO2 declines significantly relative to interglacials, with the ocean serving as the primary sink for atmospheric carbon loss. Geological records indicate an increase in carbon storage in the glacial North Pacific, making it an important contributor to the pCO2 decline. The climate-carbon cycle dynamics driving the increase in deep North Pacific carbon storage remain highly controversial; compared to the abundant data available for the North Atlantic, the research foundation is particularly weak. Based on paleoceanographic carbon cycle proxies from North Pacific sites, previous studies have proposed the “deep convection hypothesis”, suggesting that deep convection may have existed in the glacial North Pacific, enhancing surface nutrient utilization efficiency and thereby increasing deep carbon storage. However, existing research lacks a quantitative understanding of the formation conditions for glacial North Pacific deep convection, its carbon cycle dynamics, and its impact on atmospheric pCO2. To address the relationship between glacial North Pacific deep convection and air-sea carbon balance, here we employed a state-of-the-art ocean carbon cycle model to conduct a series of anti-hosing experiments in the North Pacific. We show that, with Southern Ocean processes held constant, the presence of deep convection in the glacial North Pacific would disrupt the North Pacific halocline structure, induce diapycnal mixing, and release carbon from the deep Pacific reservoir, thereby hindering oceanic carbon storage and ultimately attenuating the glacial decline in atmospheric pCO2—inconsistent with predictions of the “deep convection hypothesis”. Conversely, with the presence of intermediate-depth convection in the glacial North Pacific, redistribution of surface alkalinity and dissolved inorganic carbon concentrations can reduce the pCO2 difference between the sea surface and atmosphere, making the North Pacific a carbon sink, aligning with geological records. Further comparisons between numerical simulations and records highlight the complexity of glacial North Pacific carbon cycle processes, necessitating improvements to North Pacific salinity flux schemes in future numerical simulations, while incorporating paleoenvironmental records and taking into account the location, intensity, and depth of possible convection processes.