Rapid anthropogenic changes in CO2 and pH in the Atlantic Ocean: 2003-2014

The extended multilinear regression method is used to determine the uptake and storage of anthropogenic carbon in the Atlantic Ocean based on repeat occupations of four cruises from 1989 to 2014 (A16, A20, A22, and A10), with an emphasis on the 2003-2014 period. The results show a significant increase in basin-wide anthropogenic carbon storage in the North Atlantic, which absorbed 4.4 +/- 0.9 Pg C decade(-1) from 2003 to 2014 compared to 1.9 +/- 0.4 Pg C decade(-1) for the 1989-2003 period. This decadal variability is attributed to changing ventilation patterns associated with the North Atlantic Oscillation and increasing release of anthropogenic carbon into the atmosphere. There are small changes in the uptake rate of CO2 in the South Atlantic for these time periods (3.7 +/- 0.8 Pg C decade(-1) versus 3.2 +/- 0.7 Pg C decade(-1)). Several eddies are identified containing similar to 20% more anthropogenic carbon than the surrounding waters in the South Atlantic demonstrating the importance of eddies in transporting anthropogenic carbon. The uptake of carbon results in a decrease in pH of similar to 0.0021 +/- 0.0007 year(-1) for surface waters during the last 10 years, in line with the atmospheric increase in CO2.