On the temporal increase of anthropogenic CO2 in the subpolar North Atlantic

• Published in: Deep Sea Research Part I: Oceanographic Research Papers
• Main Authors: Friis, K., Körtzinger, Arne, Pätsch, J., Wallace, Douglas W. R.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier 2005
• Subjects: North Atlantic
• Online Access: https://oceanrep.geomar.de/id/eprint/4991/; https://oceanrep.geomar.de/id/eprint/4991/1/1-s2.0-S0967063705000087-main.pdf; https://doi.org/10.1016/j.dsr.2004.11.017

The subpolar North Atlantic (NA) plays a key role in the oceanic uptake of anthropogenic CO2. The availability of a historical high quality data set from the Transient Tracers in the Ocean North Atlantic Study (TTO-NAS) in 1981, together with data from recent studies in 1997 and 1999, makes it possible to assess the temporal increase of anthropogenic CO2 (View the MathML sourceCTant) in the region. We introduce an extension of a previous published empirical approach for estimating temporal increases of View the MathML sourceCTant, which is known as multiple linear regression approach (MLR). The method is based on a multiple linear-regression model employing hydrographic and chemical parameters. The accuracy of the extended MLR calculation (eMLR) proposed here is estimated to be ±3 μmol/kg for a parameterization based on potential temperature, total alkalinity, silicate, and phosphate. Calculated increases of View the MathML sourceCTant (View the MathML sourceΔCTant(PO4)) for the time period 1981–1997 are 1–20 μmol/kg at depths greater than 100 m. The distribution corresponds well to silicate and CFC-12 distributions. Open ocean profiles show a relative minimum between 300 and 1000 m, which is not apparent in profiles of the total View the MathML sourceCTant concentration. The View the MathML sourceΔCTant(PO4) inventory calculation for the northern NA region (40–65°N) yields a change in anthropogenic CO2 storage of 4.2 (±1) pg C over the 16-yr time period 1981–1997. This is equivalent to a mean annual View the MathML sourceCTant increase of 0.27 (±0.06) pg C/yr or more than 10% of the global ocean uptake for this period.