Trends of anthropogenic CO2 storage in North Atlantic water masses

A high-quality inorganic carbon system database, spanning over three decades (1981-2006) and comprising of 13 cruises, has allowed the applying of the phi C degrees(T) method and coming up with estimates of the anthropogenic CO2 (C-ant) stored in the main water masses of the North Atlantic. In the studied region, strong convective processes convey surface properties, like C-ant, into deeper ocean layers and grants this region an added oceanographic interest from the point of view of air-sea CO2 exchanges. Generally, a tendency for decreasing C-ant storage rates towards the deep layers has been observed. In the Iberian Basin, the North Atlantic Deep Water has low C-ant concentrations and negligible storage rates, while the North Atlantic Central Water in the upper layers shows the largest C-ant values and the largest annual increase of its average concentration (1.13 +/- 0.14 mu mol kg(-1) yr(-1)). This unmatched rate of change in the C-ant concentration of the warm upper limb of the Meridional Overturning Circulation decreases towards the Irminger basin (0.68 +/- 0.06 mu mol kg(-1) yr(-1)) due to the lowering of the buffering capacity. The mid and deep waters in the Irminger Sea show rather similar C-ant concentration rates of increase (between 0.33 and 0.45 mu mol kg(-1) yr(-1)), whereas in the Iceland basin these layers seem to have been less affected by C-ant. Overall, the C-ant storage rates in the North Atlantic subpolar gyre during the first half of the 1990s, when a high North Atlantic Oscillation (NAO) phase was dominant, are similar to 48% higher than during the 1997-2006 low NAO phase that followed. This result suggests that a net decrease in the strength of the North Atlantic sink of atmospheric CO2 has taken place during the present decade. The changes in deep-water ventilation are the main driving processes causing this weakening of the North Atlantic CO2 sink.

Full Text

FilePagesSizeAccess
Publisher's official version
19599 Ko
How to cite
Perez F. F, Vazquez-Rodriguez M., Mercier Herle, Velo A., Lherminier Pascale, Rios A. F. (2010). Trends of anthropogenic CO2 storage in North Atlantic water masses. Biogeosciences. 7 (5). 1789-1807. https://doi.org/10.5194/bg-7-1789-2010, https://archimer.ifremer.fr/doc/00006/11706/

Copy this text