The seas are unable to absorb all the carbon dioxide we're producing:
The study's lead author, Dr Pep Canadell, executive director of the Global Carbon Project, explained "Fifty years ago, for every tonne of CO2 emitted, 600 kg were removed by natural sinks. In 2006 only 550 kg were removed per tonne and that amount is falling. In addition to the growth of global population and wealth, we now know that significant contributions to the growth of atmospheric CO2 arise from the slow down of natural sinks and the halt to improvements in carbon intensity."...
"There are regional differences in the efficiency of natural sinks. Half of decline in the efficiency of the ocean sink is due to the intensification and poleward movement of the westerly winds in the Southern ocean", said contributing author Corinne Le Quere of the University of East Anglia.