The northern European shelf as an increasing net sink for CO 2

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

[学科分类] 大气科学