Decadal changes of anthropogenic and total carbon in the Atlantic Ocean

Reiner Steinfeldt1, Monika Rhein2 and Dagmar Kieke1, (1)University of Bremen, Bremen, Germany, (2)Univ Bremen, FB1, Bremen, Germany
At present, the ocean takes up about 30% of the global emissions of anthropogenic CO2 (Cant). Cant enters the ocean at the surface by air-sea gas exchange and is transferred into the ocean's interior by the formation and spreading of denser water masses. Due to the presence of recently ventilated North Atlantic Deep Water, the Atlantic has higher Cant column inventories compared to the Pacific and Indian Ocean. Here we will make use of basinwide Atlantic sections occupied within the WOCE, CLIVAR and GO-SHIP programs and the German national project RACE to infer the distribution of total inorganic carbon (TCO2), remineralized and anthropogenic carbon. Cant is calculated by the TTD method based on transient tracer data such as CFCs and SF6 and is thus independent of direct carbon observations. We will show that over the last 30 years, the changes in TCO2 over large areas of the Atlantic are mainly driven by the increase in Cant. In some regions, the variability in ocean ventilation and circulation also have an impact on the Cant concentrations. There, the Cant changes deviate from the expected increase due to the rising atmospheric CO2. As older/younger waters accumulate larger/smaller amounts of remineralized carbon, changes in ventilation age will also effect this quantity. Therefore, we will discuss the influence of changes in ventilation age both on Cant and remineralized carbon.