Rapid increase of observed \DIC\ and pCO2 in the surface waters of the North Sea in the 2001-2011 decade ascribed to climate change superimposed by biological processes

• Published in: Marine Chemistry
• Main Authors: Clargo, Nicola M., Salt, Lesley A., Thomas, Helmuth, Baar, Hein J.W., De
• Other Authors: CHImie Marine (CHIM), Adaptation et diversité en milieu marin (AD2M), Station biologique de Roscoff Roscoff (SBR), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Station biologique de Roscoff Roscoff (SBR), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Dalhousie University Halifax
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2015
• Subjects: Carbon dioxide (CO2); [SDV]Life Sciences [q-bio]; [SDE]Environmental Sciences; Ocean acidification
• Online Access: https://hal.science/hal-01251671; https://doi.org/10.1016/j.marchem.2015.08.010

Cycles of metals and carbon in the oceans - A tribute to the work stimulated by Hein de Baar International audience Abstract The \CO2\ system in the North Sea over the 2001-2011 decade was investigated using four comprehensive basin-wide datasets covering the late summer periods of 2001, 2005, 2008 and 2011. We find that rises in surface water \DIC\ and pCO2 exceeded concurrent rises in atmospheric pCO2, which we attribute primarily to biological activity in late summer. After accounting for this biological signal, the observed ocean acidification occurs at a rate that is consistent with concurrent atmospheric and open ocean \CO2\ increases over the 2001-2011 decade. Nevertheless, we do find a consistent reduction in \CO2\ undersaturation in the \NNS\ and an increase in \CO2\ supersaturation in the SNS. We propose that the synergistic effects of increasing atmospheric pCO2 and subsequent decrease in seawater buffering capacity, together with rising sea surface temperatures in the future oceans, may reduce the strength of the North Sea as a \CO2\ sink. Such a reduction would diminish the efficiency of this region as a continental shelf pump with respect to uptake of \CO2\ by the sea. Ultimately this would constitute a positive feedback mechanism, i.e. enhancing the airborne fraction of anthropogenic \CO2\ and thus the net rate of increase of atmospheric pCO2 and subsequent global climate change.