Episodic release of CO 2 from the high-latitude North Atlantic Ocean during the last 135 kyr

Antarctic ice cores document glacial-interglacial and millennial-scale variability in atmospheric pCO 2 over the past 800 kyr. The ocean, as the largest active carbon reservoir on this timescale, is thought to have played a dominant role in these pCO 2 fluctuations, but it remains unclear how and where in the ocean CO 2 was stored during glaciations and released during (de)glacial millennial-scale climate events. The evolution of surface ocean pCO 2 in key locations can therefore provide important clues for understanding the ocean's role in Pleistocene carbon cycling. Here we present a 135-kyr record of shallow subsurface pCO 2 and nutrient levels from the Norwegian Sea, an area of intense CO 2 uptake from the atmosphere today. Our results suggest that the Norwegian Sea probably acted as a CO 2 source towards the end of Heinrich stadials HS1, HS4 and HS11, and may have contributed to the increase in atmospheric pCO 2 at these times.