In April 2017, SOLAS and IMBER have disbanded their two carbon working groups that, based on the Joint SOLAS/IMBER Carbon Implementation Plan, were charged with coordination and synthesis of ocean carbon research related to both: ocean surface and ocean interior. Seeking new science directions, SOLAS and IMBER proposed an open discussion amongst all and any programs interested in ocean carbon research. IOCCP, GCP, CLIVAR, WCRP C-challenge and SOLAS and IMBER representatives expressed interest in such discussion and an initial, scoping side-meeting during the ICDC10 in Interlaken was organized. The meeting was attended by 13 participants representing the above mentioned programs and was chaired by Nicolas Gruber, a former chair of the SOLAS/IMBER Carbon Working Group 2.

The meeting started with a quick round of introductions, followed by an outline of the key discussion items for this meeting. It was positively noted that all major international programs dealing with the ocean carbon cycle were represented at this meeting. The following questions were discussed: 1) is there a need for an international coordination in ocean carbon cycle research that goes beyond what is currently done? 2) If the answer to 1 is yes, then (i) how broad should such an activity be, (ii) what are the key questions that should guide this activity, and (iii) what kind of organizational setup do we envisage/is possible?

The answer to the first question was a clear yes, perhaps most strongly expressed by IOCCP, who is currently lacking a scientific partner to develop and implement a science-based strategy related to marine carbon cycle. But the gap left after disbanding of the SOLAS-IMBER Carbon working groups 1 and 2 is felt by the other organisations, too. For example, the lack of coordinated ocean carbon cycle simulations was mentioned both with regard to CMIP6 and in the context of GCP's efforts to establish annual carbon budgets. Many programs are currently including ocean carbon related activities in their science plans, but in none of these organizations the ocean carbon cycle obtains adequate attention. This is neither efficient nor effective.

There was a less clear consensus with regard to the question of how broad such a new initiative ought to be. A good fraction of the participants were of the opinion that any new initiative would have to go beyond the (inorganic) carbon cycle, and include other related biogeochemical properties such as nutrients, oxygen, and N₂O, i.e., very much in the spirit of the biogeochemical suite of Essential Ocean Variables that were developed through the GOOS Biogeochemistry Panel (IOCCP). At the highest level, delineating an initiative from the perspective of ocean health was mentioned as a way forward, particularly since such a line of argument would be attractive for potential funders and FutureEarth. A somewhat smaller fraction was arguing more in favour of a rather focused approach, staying mostly with inorganic carbon, i.e., within the scope of the past SOLAS/IMBER working groups 1 and 2.

In terms of the key scientific questions that would drive such a new initiative, most mentioned issues at the interface between biogeochemistry and physical oceanography, while biological processes were not identified. This might have been due to the lack of relevant expertise in the room. Concrete examples included decadal variability, meso- and submesoscale processes, optimal observing system design, multiple stressors considerations, and the interaction of the fluxes of heat and carbon fluxes and their storage. There was also a clear consensus that there should be a single entity dealing with surface and interior ocean carbon issues of interest.

On an organizational level, no clear consensus has emerged yet, although it was strongly stated that a clear narrative about what this organization represents and what its goals and ambitions are is needed. Particularly since the current view from e.g., the Belmont Forum, is that this community is rather fragmented. Associating a carbon-focused activity with CLIVAR was viewed as not feasible/desirable, although the large benefits of a close collaboration were uniformly recognized. RECCAP2 was identified as a potential seed project.

Furthermore, a couple of options for structuring of this new entity were proposed. On one hand there was a proposal that such an organization needs at its core people who run the office and are responsible for coordination who provide scientific leadership. The emerging Ocean Knowledge-Action Network (Ocean KAN) framework was identified as a potential avenue to move forward. The approach offers the stability of a project office and a clear organizational status. Challenges with such an approach include the need for fund-raising related to staff and operations of the program as well as the need to overcome potentially adverse reactions of the community to creating yet another layer of coordination.

An alternative proposed approach was to form an explicitly cross-program group (ocean carbon think-tank) that would be supported jointly by some or all programs with links to but no direct focus on ocean carbon (CLIVAR and/or IMBER and/or SOLAS and/or GCP) and IOCCP. Such a group would include interested members of the member organization SCs as well as others. The approach offers potentially immediate activity and clear and direct connection to all existing interested programs. Challenges with this approach include the need for all involved existing programs to agree to co-sponsor the activities of such a cross-program ocean carbon think-tank and to jointly agree on details of the implementation of developed future activities.

In response, the individual representatives were asked to bring these issues as a discussion items back to their respective organizations to further explore proposed options, while considering others as well.

In conclusion, the need for a science development-focused, international ocean carbon/biogeochemistry program was clearly articulated and supported by all present. As the issue is considered pressing, it's our intention to continue this scoping activity until the community will arrive at a feasible solution.