Episodic release of CO<sub>2</sub> from the high-latitude North Atlantic Ocean during the last 135 kyr.

Ezat, Mohamed M; Rasmussen, Tine L; Hönisch, Bärbel; Groeneveld, Jeroen; deMenocal, Peter · Nat Commun · 2017

basic_science · Level V

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Abstract

Antarctic ice cores document glacial-interglacial and millennial-scale variability in atmospheric pCO<sub>2</sub> 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<sub>2</sub> fluctuations, but it remains unclear how and where in the ocean CO<sub>2</sub> was stored during glaciations and released during (de)glacial millennial-scale climate events. The evolution of surface ocean pCO<sub>2</sub> 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<sub>2</sub> and nutrient levels from the Norwegian Sea, an area of intense CO<sub>2</sub> uptake from the atmosphere today. Our results suggest that the Norwegian Sea probably acted as a CO<sub>2</sub> source towards the end of Heinrich stadials HS1, HS4 and HS11, and may have contributed to the increase in atmospheric pCO<sub>2</sub> at these times.