Anthropogenic CO2 accumulation rates in the North Atlantic Ocean from changes in the 13C/12C of dissolved inorganic carbon

• Published in: Global Biogeochemical Cycles
• Main Authors: Quay, P., Sonnerup, R., Stutsman, J., Maurer, J., Körtzinger, Arne, Padín, X. A., Robinson, Carol
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Geophysical Union 2007
• Subjects: Ner; North Atlantic
• Online Access: http://hdl.handle.net/10261/50286; https://doi.org/10.1029/2006GB002761

15 páginas, 11 figuras, 1 tabla The anthropogenic CO2 accumulation rate for the North Atlantic Ocean was estimated on the basis of the decrease in the δ 13C of the dissolved inorganic carbon measured between cruises in 1981 (Transient Tracers in the North Atlantic), 1993 (OACES) and 2003 (Repeat Hydrography). A mean depth-integrated δ 13C change of −15.0 ± 3.8‰ m yr−1 was estimated by applying a multiple linear regression approach to determine the anthropogenic δ 13C decrease at 22 stations where δ 13C depth profiles were compared. The largest and deepest anthropogenic δ 13C decreases occurred in the subpolar ocean and, in contrast, the smallest and shallowest decreases occurred in the tropical ocean. A mean anthropogenic CO2 accumulation rate of 0.63 ± 0.16 mol C m−2 yr−1 (0.32 ± 0.08 Pg C yr−1) in the North Atlantic Ocean over the last 20 years was determined from the mean depth-integrated δ 13C change and a ratio of anthropogenic δ 13C to DIC change of −0.024‰ (μmol kg−1)−1. Only half of the accumulated anthropogenic CO2 in the North Atlantic during the last 20 years was the result of air-sea CO2 uptake, based on a comparison of the air-sea 13CO2 flux to the DIC13 inventory change, with the other half likely a result of northward advective transport. This study was supported in part by the UK Natural Environment Research Council through the Atlantic Meridional Transect consortium (NER/O/S/2001/00680) and core strategic research funding to Plymouth Marine Laboratory. This is contribution 145 of the AMT program. In particular we want to acknowledge the financial support that NOAA’s Office of Global Programs has provided, most recently under the Joint Institute for the Study of Atmosphere and Oceans (JISAO) under NOAA Cooperative Agreement NA67RJ0155. Peer reviewed