A decrease in the sink for atmospheric CO2 in the North Atlantic

Abstract

Global ocean carbon models and available syntheses of the oceanic CO2 flux suggest that the North Atlantic subpolar gyre (50°N-70°N, 80°W-10°W) is a region of increasing uptake of CO2 from the atmosphere, with the oceanic partial pressure of CO2 (pCO2) increasing more slowly than the atmospheric CO2 over time. Our analysis of available CO2 data shows that, on the contrary, seawater pCO2 has increased faster than the atmosphere in recent decades, especially in summer, resulting in a decrease in uptake from the atmosphere. A decrease in the biological productivity of the region may be the underlying cause of this trend. From the observed trend we estimated a significant decrease in the annual carbon uptake in this region. Copyright 2004 by the American Geophysical Union.