Enhancement of the North Atlantic CO 2 sink by Arctic Waters

• Published in: Biogeosciences
• Main Authors: J. Olafsson, S. R. Olafsdottir, T. Takahashi, M. Danielsen, T. S. Arnarson
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2021
• Subjects: Ecology; QH540-549.5; Life; QH501-531; Geology; QE1-996.5; Arctic; Iceland; North Atlantic; Northwest Atlantic
• Online Access: https://doi.org/10.5194/bg-18-1689-2021; https://doaj.org/article/84a3df5c95f546e4b5d411ad2b808cbc

The North Atlantic north of 50 ∘ N is one of the most intense ocean sink areas for atmospheric CO 2 considering the flux per unit area, 0.27 Pg-C yr −1 , equivalent to −2.5 mol C m −2 yr −1 . The northwest Atlantic Ocean is a region with high anthropogenic carbon inventories. This is on account of processes which sustain CO 2 air–sea fluxes, in particular strong seasonal winds, ocean heat loss, deep convective mixing, and CO 2 drawdown by primary production. The region is in the northern limb of the global thermohaline circulation, a path for the long-term deep-sea sequestration of carbon dioxide. The surface water masses in the North Atlantic are of contrasting origins and character, with the northward-flowing North Atlantic Drift, a Gulf Stream offspring, on the one hand and on the other hand the cold southward-moving low-salinity Polar and Arctic waters with signatures from Arctic freshwater sources. We have studied by observation the CO 2 air–sea flux of the relevant water masses in the vicinity of Iceland in all seasons and in different years. Here we show that the highest ocean CO 2 influx is to the Arctic and Polar waters, respectively, <math xmlns="http://www.w3.org/1998/Math/MathML" id="M13" display="inline" overflow="scroll" dspmath="mathml"><mrow><mo>-</mo><mn mathvariant="normal">3.8</mn><mo>±</mo><mn mathvariant="normal">0.4</mn></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="52pt" height="10pt" class="svg-formula" dspmath="mathimg" md5hash="bbacc4c36339bdcb3a2b068c678194a7"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-18-1689-2021-ie00001.svg" width="52pt" height="10pt" src="bg-18-1689-2021-ie00001.png"/></svg:svg> and <math xmlns="http://www.w3.org/1998/Math/MathML" id="M14" display="inline" overflow="scroll" dspmath="mathml"><mrow><mo>-</mo><mn mathvariant="normal">4.4</mn><mo>±</mo><mn ...