Addressing the carbon question: new insights from a synthesis of UK and European observations of marine CO2 and ocean acidification

Chair: Samantha Siedlecki

Clare Ostle (1)*, Naomi Greenwood (2), Silvana Birchenough (2), David Pearce (2), Dorothee Bakker (1) & Phil Williamson (3)

1 University of East Anglia, Norwich, UK
2 Centre for Environment, Fisheries and Aquaculture Science (Cefas), Lowestoft, UK
3 Natural Environment Research Council (NERC), Swindon, UK

Background
Increasing atmospheric concentrations of carbon dioxide (CO2) are altering the carbonate chemistry and carbon uptake capacity of the ocean, with potentially significant ecological and socio-economic consequences. Although often presented as global mean values and projections, ocean acidification processes are highly dynamic, with spatial and temporal variability driven by physical and biological factors.

In recent years, UK-led research efforts have been focussed on monitoring and investigating the carbonate system in the Northwest European shelf seas and surrounding oceanic regions and the implications of potential future changes. Here we present preliminary data from a synthesis project involving a wide range of datasets. Focusing primarily on the 2010-2015 period, we paint an over-arching picture of key findings and trends in a wider European and North Atlantic context.

Methods
Discrete measurements of dissolved inorganic carbon, total alkalinity, pH and sea surface pCO2 (partial pressure of CO2) are collated and investigated regionally.

Findings
Across a range of marine environments, from the open ocean to coastal regions, there is strong variability in carbonate datasets. We discuss the strong seasonal and inter-annual variability in the carbonate system in the context of physical mixing and biological processes.

Conclusions
With the continued increase in atmospheric CO2 and sea surface temperatures, there will likely be a reduction in carbon uptake by the ocean, and a continued negative feedback. Combined, these trends will have significant impacts on carbon flux and are likely to impact ecosystem dynamics and export efficiency. With such high spatio-temporal variability between coastal and open ocean regions, extending and maintaining times series of such datasets is critical to improving our understanding and monitoring of carbon cycling as well as improving climate model accuracy.