The stable isotopic composition of seawater and the carbon isotopic composition of dissolved inorganic carbon are essential ocean tracers that have been widely measured since the 1960s. They are in particular used to investigate the hydrological cycle and the exchanges between the ocean with , sea ice, ice sheets, the atmosphere and continental runoffs, as well as the bio-geochemical cycles, the anthropogenic carbon penetration, and the associated acidification of the oceans. Moreover, they are used to validate proxy-tracers measured in natural archives for reconstructing past climate evolution. Modeling studies suggest that the isotopes are currently experiencing large changes linked to global warming and the associated changes in the hydrological and biogeochemical cycles. However, using and interpreting current data sets is often hampered by substantial issues in data collection/measurement, validation, analysis, and synthesis, as well as in their interpretation.

This splinter session is aimed at sharing your experience with such data, whether you are data producers or data users, and discuss what could be done to improve the situation. You are welcome to come with a few slides on a USB key to provide material for discussion. We should in particular discuss the next steps, such as setting a working groups and meetings, maybe also a web site to further share our experience, reports, papers, venues... exchanging water samples or reference materials...