Reanalyses of anthropogenic carbon uptake etc

Ocean state estimation is applied to reconstruct the air-sea CO2 flux and anthropogenic carbon inventory of the high northern latitudes and the transports of Dissolved Inorganic Carbon (DIC) over the entrances of the Greenland-Iceland-Norwegian (GIN) Sea and the Arctic Ocean over the last 50 years.

Model: German contribution to the Estimating the Circulation and Climate of the Ocean (GECCO).

Circulation and hydrography are optimized by constraining both the forcing and the initial conditions by assimilating the majority of available ocean observations.

Integrations: years 1852-2011. 

1: fixed preindustrial atmospheric CO2 concentration of 285ppm.

2: realistic, observed CO2 concentrations.

Both, air-sea fluxes and DIC transports over key passages compare reasonably well with the few reported observation-based estimations.

Temporal mean air-sea CO2 fluxes over the GIN Sea (Arctic Ocean) in the last 50 years amounts to 0.10 (0.057) Gt C yr-1 and increased by 50 (105)% when comparing the 1960s with the last ten years. Storage of anthropogenic carbon increased from 0.5Gt to 1.2Gt for the GIN Sea, and from 1.0Gt to 2.4Gt for the Arctic Ocean. Roughly 75% of the anthropogenic carbon is stored in the upper 1000m. DIC transports over key passages of the region all increased strongly. In summary, CO2 air-sea fluxes, as well anthropogenic carbon storage and transports exhibit positive, progressive trends for both the GIN Sea and the Arctic Ocean.

Report, plots etc.