A global estimate of the full oceanic ¹³C Suess effect since the preindustrial

Abstract

We present the first estimate of the full global ocean 13 C Suess effect since preindustrial times, based on observations. This has been derived by first using the method of Olsen and Ninnemann (2010) to calculate 13 C Suess effect estimates on sections spanning the world ocean, which were next mapped on a global 1°× 1°grid. We find a strong 13 C Suess effect in the upper 1000 m of all basins, with strongest decrease in the subtropical gyres of the Northern Hemisphere, where δ 13 C of dissolved inorganic carbon has decreased by more than 0.8‰ since the industrial revolution. At greater depths, a significant 13 C Suess effect can only be detected in the northern parts of the North Atlantic Ocean. The relationship between the 13 C Suess effect and the concentration of anthropogenic carbon varies strongly between water masses, reflecting the degree to which source waters are equilibrated with the atmospheric 13 C Suess effect before sinking.Finally, we estimate a global ocean inventory of anthropogenic CO 2 of 92 ± 46 Gt C. This provides an estimate that is almost independent of and consistent, within the uncertainties, with previous estimates.

Southern Ocean controls of the vertical marine δ<sup>13</sup>C gradient – a modelling study

“…The contribution of biology to the modelled δ 13 C distribution is generally below 45 % and has a steep gradient from the surface to the deep ocean. The (thermodynamic) fractionation effect of air-sea gas exchange on δ 13 C is strongly impeded by the long equilibration time of 13 C, which results in room for biological processes to contribute significantly to δ 13 C and Δδ 13 C (Eide et al, 2017a;Lynch-Stieglitz et al, 1995;Schmittner et al, 2013). In the deep ocean below 250m, the influence 25 of biology increases to 35-45 % due to the remineralisation of POC, with the exception of the Arctic Ocean where no POC production is modelled due to the sea ice cover ( Fig.…”

Coastal primary productivity changes over the last millennium: a case study from the Skagerrak (North Sea)

“…C decrease between the preindustrial and modern period observed in the North Atlantic (Eide et al, 2017). …”

The [simple carbon project] model v1.0

“…C for the effects of industrial emissions (the "Suess" effect) and bomb radiocarbon in the atmosphere using published estimates (Broecker et al, 1980;Key, 2001;Sabine et al, 2004;Eide et al, 2017). For example, Eide et al (2017) establishes a mathematical relationship between Suess δ 13 C and CFC-12 in the ocean, which we applied using GLODAP CFC-12 data to correct the ocean δ 13 C data.…”

“…For example, Eide et al (2017) establishes a mathematical relationship between Suess δ 13 C and CFC-12 in the ocean, which we applied using GLODAP CFC-12 data to correct the ocean δ 13 C data. We force the model with late Holocene average data for atmosphere CO 2 , δ 13 C and ∆ 14 C (data sources in Table 1).…”

“…A mean production rate of 1.57 atom m (Key, 2001). For use in the model, this estimate needs to be converted and Sarmiento (1985) Organic δ 13 C fractionation factor ∼0.975 Toggweiler and Sarmiento (1985) C/P in org "Redfield ratio" 130 Takahashi et al (1985) Rain ratio (carbonate:org in sinking particles) 0.07 Sarmiento et al (2002) CaCO3 dissolution rate (units day −1 ) 0.38 Hales and Emerson (1997) n order of CaCO3 dissolution reaction rate 1.0 Hales and Emerson (1997) Ksp solubility coefficient for calcite Various Mucci (1983) Carbon chemistry solubility and dissociation coefficients Various Weiss (1974), Lueker et al (2000) Atmosphere radiocarbon production rate (atoms s −1 ) ∼1.6 Key (2001) Suess and bomb radiocarbon corrections Various Broecker et al (1980), Key (2001), Sabine et al (2004), Eide et al (2017) Radiocarbon decay rate (yr −1 ) 1/8267 Stuiver and Polach (1977) Volcanic emissions flux CO2 (mol C yr …”