The northern European shelf as an increasing net sink for CO<sub>2</sub>

Abstract. We developed a simple method to refine existing open-ocean maps and extend them towards different coastal seas. Using multi-linear regression we produced monthly of surface ocean fCO2 in the northern European seas (the North Sea, Baltic Norwegian Coast Barents Sea) covering time period from 1998 2016. A comparison with gridded Surface Ocean CO2 Atlas (SOCAT) v5 data revealed mean biases standard deviations 0 ± 26 µatm 16 along Coast, 19 Sea 2 42 Sea. used these investigate trends fCO2, pH air–sea flux. The are smaller than atmospheric trend most studied regions. only exception this is western part where sea increases by yr?1, which similar trend. does not show significant Here, variability was much larger expected trends. Consistently, were for an increase pace rise levels. calculated fluxes that regions net sinks CO2. Only southern emitted atmosphere. Especially sink strength increased during period.