Biological Responses to Ocean Acidification Are Changing the Global Ocean Carbon Cycle

Global Biogeochemical Cycles, Journal Year: 2025, Volume and Issue: 39(3)

Published: March 1, 2025

Abstract Increased oceanic uptake of CO 2 due to rising anthropogenic emissions has caused lowered pH levels (ocean acidification) that are hypothesized diminish biotic calcification and reduce the export total alkalinity ( A T ) as carbonate minerals from surface ocean or their burial in coastal sediments. This “CO ‐biotic feedback” is a negative feedback on atmospheric , elevated increase ocean's capacity . We detect signatures this global for first time using repeat hydrographic measurements seawater property prediction algorithms. Over course past 30 years, we find an 0.072 ± 0.023 μmol kg −1 yr which would have approximately 20 Tmol additional accumulate ocean. finding suggests measurably perturbing cycling carbon planetary scale by disrupting biological patterns. More observations be required understand effects regional basis fully characterize its potential efficiency marine dioxide removal technology.

Language: Английский

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Composite model-based estimate of the ocean carbon sink from 1959 to 2022

Biogeosciences, Journal Year: 2025, Volume and Issue: 22(6), P. 1631 - 1649

Published: March 28, 2025

Abstract. The ocean takes up around one-quarter of anthropogenically emitted carbon and is projected to remain the main sink once global temperatures stabilize. Despite importance this natural sink, estimates its strength over last decades uncertain, mainly due too few unevenly sampled observations shortcomings in models their setups. Here, I present a composite model-based estimate annually averaged from 1959 2022 by combining higher-frequency variability hindcast mode long-term trends fully coupled Earth system models. Ocean reproduce observed climate variability, but spin-up strategy likely leads that are weak, whereas simulate own internal better represent trends. By these two modelling approaches, keep each approach remove respective weaknesses. This 125±8 Pg C similar magnitude best Global Carbon Budget 70 % less uncertain.

Language: Английский

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Mixing Accounts for More Than Half of Biogeochemical Changes Along Mode Water Ventilation Pathways

Geophysical Research Letters, Journal Year: 2025, Volume and Issue: 52(7)

Published: April 10, 2025

Abstract Mode waters are critical for ocean ventilation and carbon sequestration. Using observations, we trace their subduction pathways biogeochemical evolution. Solving modified mixing equations that account respiration reveals less than 50% of the oxygen changes along mode water due to within mass, rest being with oxygen‐poorer surrounding waters. Consequently, measured in or Apparent Oxygen Utilization overestimate by a factor up two, as do derived quantities such remineralized carbon. Measured nitrate either underestimate remineralization depending on concentrations. Mean true rates range from −0.1 −0.4 mol . Applying fixed stoichiometric ratio this respiration, find total export is highest Southern Ocean waters, while subtropical

Language: Английский

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CO₂ Uptake in the Pacific From 1985 to 2018: A Comparative Assessment of Observation‐ and Model‐Based Estimates

Global Biogeochemical Cycles, Journal Year: 2025, Volume and Issue: 39(5)

Published: May 1, 2025

Abstract As a contribution to the second REgional Carbon Cycle Assessment and Processes effort, we compare net anthropogenic sea‐air CO 2 fluxes, accumulation rates in ocean interior their trends Pacific Ocean by analyzing results from state‐of‐the‐art observation‐based estimates global biogeochemistry models (GOBMs) over period 1985–2018. The ensemble‐mean fluxes integrated (44°S–62°N) are −0.41 ± 0.12 PgC yr −1 p products −0.51 0.16 GOBMs. flux GOBMs (−0.71 0.10 ) is 1.4 times as large flux, with particularly uptake equatorial region (−0.34 0.03 significantly offsetting natural outgassing there (+0.72 0.06 ). basin‐wide has increased at similar mean of −0.09 −0.08 0.02 decade GOBMs, respectively, comparable increase −0.10 0.01 However, notable mismatch trend change that exists between (+0.00 (−0.04 yet be resolved. rate +0.76 0.17 . This nearly balanced also encompassed previous estimates.

Language: Английский

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Indian Ocean Acidification and Its Driving Mechanisms Over the Last Four Decades (1980–2019)

Global Biogeochemical Cycles, Journal Year: 2024, Volume and Issue: 38(9)

Published: Sept. 1, 2024

Abstract This paper aims to study the changes in Indian Ocean seawater pH response sea‐surface temperature, salinity, dissolved inorganic carbon (DIC), and total alkalinity (ALK) over period 1980–2019 its driving mechanisms using a high‐resolution regional model outputs. The analysis indicates that rate of change declining Arabian Sea (AS), Bay Bengal (BoB), Equatorial (EIO) is −0.014 0.002, 0.001, −0.015 0.001 unit dec −1 , respectively. Both AS BoB (EIO), highest (lowest) decadal DIC trend found during 2000–2009. surface acidification has accelerated throughout IO region 2010–2019 compared previous decades. Further, our El Ninõ positive Dipole events lead an enhancement acidification. increasing anthropogenic CO 2 uptake by ocean dominantly controls 80% (94.5% 85.7%) net (1980–2019) (BoB EIO), whereas warming 14.4% (13.4% 7.0%) trends EIO). ALK contribute enhancing 5.0%. dominates after EIO and, similar AS, contributes negative 10.7%. In contrast, it buffering effect BoB, suppressing −5.4%.

Language: Английский

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