High anthropogenic carbon content in the eastern Mediterranean

This work presents data of dichlorodifluoromethane (CFC‐12), dissolved inorganic carbon and total alkalinity from a cruise to the Mediterranean Sea during October–November 2001, with the main focus on the CFC‐12 data and on the eastern basin. Using the transit time distribution method, the anthropogenic carbon concentrations in the basin were estimated. Results were cross‐checked with a back‐calculation technique. The entire water column of the Mediterranean Sea contains anthropogenic CO2, with minimum concentrations of 20.5 μmol kg−1 (error range: 16.9–27.1 μmol kg−1) in the most eastern part of the basin at intermediate depths, where the waters' mean age is >130 yr. Column inventories of up to 154 mol m−2 (132–179 mol m−2) are found and a total inventory of 1.7 Pg (1.3–2.1 Pg) of anthropogenic carbon in the Mediterranean Sea was estimated. There is a net flux of 38 Tg yr−1 (30–47 Tg yr−1) of dissolved inorganic carbon through the Strait of Gibraltar into the Atlantic Ocean and an opposite net flux of 3.5 Tg yr−1 (−1.8–9.2 Tg yr−1) of anthropogenic carbon into the Mediterranean Sea.