Identification

Title

Oceanic sources, sinks, and transport of atmospheric CO₂

Abstract

We synthesize estimates of the contemporary net air-sea CO₂ flux on the basis of an inversion of interior ocean carbon observations using a suite of 10 ocean general circulation models (Mikaloff Fletcher et al., 2006, 2007) and compare them to estimates based on a new climatology of the air-sea difference of the partial pressure of CO₂ (pCO₂) (Takahashi et al., 2008). These two independent flux estimates reveal a consistent description of the regional distribution of annual mean sources and sinks of atmospheric CO₂ for the decade of the 1990s and the early 2000s with differences at the regional level of generally less than 0.1 Pg C a⁻¹. This distribution is characterized by outgassing in the tropics, uptake in midlatitudes, and comparatively small fluxes in thehigh latitudes. Both estimates point toward a small (∼ -0.3 Pg C a⁻¹) contemporary CO₂ sink in the Southern Ocean (south of 44°S), a result of the near cancellation between a substantial outgassing of natural CO₂ and a strong uptake of anthropogenic CO₂. A notable exception in the generally good agreement between the two estimates exists within the Southern Ocean: the ocean inversion suggests a relatively uniform uptake, while the pCO₂-based estimate suggests strong uptake in the region between 58°S and 44°S, and a source in the region south of 58°S. Globally and for a nominal period between 1995 and 2000, the contemporary net air-sea flux of CO₂ is estimated to be -1.7 ± 0.4 Pg C a⁻¹ (inversion) and -1.4 ± 0.7 Pg C a⁻¹ (pCO₂-climatology), respectively, consisting of an outgassing flux of river-derived carbon of ∼+0.5 Pg C a⁻¹, and an uptake flux of anthropogenic carbon of −2.2 ± 0.3 Pg C a⁻¹ (inversion) and -1.9 ± 0.7 Pg C a⁻¹ (pCO₂-climatology). The two flux estimates also imply a consistent description of the contemporary meridional transport of carbon with southward ocean transport throughout most of the Atlantic basin, and strong equatorward convergence in the Indo-Pacific basins. Both transport estimates suggest a small hemispheric asymmetry with a southward transport of between -0.2 and -0.3 Pg C a⁻¹ across the equator. While the convergence of these two independent estimates is encouraging and suggests that it is now possible to provide relatively tight constraints for the net air-sea CO₂ fluxes at the regional basis, both studies are limited by their lack of consideration of long-term changes in the ocean carbon cycle, such as the recent possible stalling in the expected growth of the Southern Ocean carbon sink.

Resource type

document

Resource locator

Unique resource identifier

code

http://n2t.net/ark:/85065/d7v125tt

codeSpace

Dataset language

eng

Spatial reference system

code identifying the spatial reference system

Classification of spatial data and services

Topic category

geoscientificInformation

Keywords

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keyword value

Text

originating controlled vocabulary

title

Resource Type

reference date

date type

publication

effective date

2016-01-01T00:00:00Z

Geographic location

West bounding longitude

East bounding longitude

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South bounding latitude

Temporal reference

Temporal extent

Begin position

End position

Dataset reference date

date type

publication

effective date

2009-02-18T00:00:00Z

Frequency of update

Quality and validity

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Conformity

Data format

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version of format

Constraints related to access and use

Constraint set

Use constraints

Limitations on public access

None

Responsible organisations

Responsible party

contact position

OpenSky Support

organisation name

UCAR/NCAR - Library

full postal address

PO Box 3000

Boulder

80307-3000

email address

opensky@ucar.edu

web address

http://opensky.ucar.edu/

name: homepage

responsible party role

pointOfContact

Metadata on metadata

Metadata point of contact