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Abstract The ocean is one of the most important sinks for anthropogenic CO2emissions. Here, I use an ocean circulation inverse model (OCIM), ocean biogeochemical models, and pCO2interpolation products to examine trends and variability in the oceanic CO2sink. The OCIM quantifies the impacts of rising atmospheric CO2, changing sea surface temperatures, and gas transfer velocities on the oceanic CO2sink. Together, these effects account for an oceanic CO2uptake of 2.2 ± 0.1 PgC yr−1from 1994 to 2007, and a net increase in the oceanic carbon inventory of 185 PgC from 1780 to 2020. However, these effects cannot account for the majority of the decadal variability shown in data‐based reconstructions of the ocean CO2sink over the past 30 years. This implies that decadal variability of the ocean CO2sink is predominantly driven by changes in ocean circulation or biology that act to redistribute both natural and anthropogenic carbon in the ocean.
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Scale‐Dependent Drivers of Air‐Sea CO 2 Flux Variability
Abstract In climate studies, it is crucial to distinguish between changes caused by natural variability and those resulting from external forcing. Here we use a suite of numerical experiments based on the ECCO‐Darwin ocean biogeochemistry model to separate the impact of the atmospheric carbon dioxide (CO2) growth rate and climate on the ocean carbon sink — with a goal of disentangling the space‐time variability of the dominant drivers. When globally integrated, the variable atmospheric growth rate and climate exhibit similar magnitude impacts on ocean carbon uptake. At local scales, interannual variability in air‐sea CO2flux is dominated by climate. The implications of our study for real‐world ocean observing systems are clear: in order to detect future changes in the ocean sink due to slowing atmospheric CO2growth rates, better observing systems and constraints on climate‐driven ocean variability are required.
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- Award ID(s):
- 2019625
- PAR ID:
- 10611071
- Publisher / Repository:
- Geophysical Research Letters
- Date Published:
- Journal Name:
- Geophysical Research Letters
- Volume:
- 51
- Issue:
- 20
- ISSN:
- 0094-8276
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1029/2024GL111911
