Continental shelves as a variable but increasing global sink for atmospheric carbon dioxide

It has been speculated that the partial pressure of carbon dioxide ( p CO 2 ) in shelf waters may lag the rise in atmospheric CO 2 . Here, we show that this is the case across many shelf regions, implying a tendency for enhanced shelf uptake of atmospheric CO 2 . This result is based on analysis of long-term trends in the air–sea p CO 2 gradient (Δ p CO 2 ) using a global surface ocean p CO 2 database spanning a period of up to 35 years. Using wintertime data only, we find that Δ p CO 2 increased in 653 of the 825 0.5° cells for which a trend could be calculated, with 325 of these cells showing a significant increase in excess of +0.5 μatm yr −1 ( p