Actions should further the understanding of the resilience to climate change and temporal and regional variability of the natural carbon inventory in the ocean. Actions should further the understanding of how the biological pump and the deep ocean carbon sink will respond to the rapid and ongoing anthropogenic changes to our planet—including warming, acidification, and deoxygenation of ocean waters. Actions should advance the scientific understanding of marine pelagic and benthic invertebrate and vertebrate carbon, the carbon services they provide (i.e. trophic cascade carbon, biomixing carbon, carbon mineralisation, bony fish carbonate, whale pump, twilight zone carbon, biomass carbon, deadfall carbon and marine vertebrate mediated carbon), and the intricate biological pathways involved in carbon cycling and the associated implications for climate regulation.

Actions should assess and model the marine vertebrate carbon services and should link them to population dynamics, with a view to gathering enough evidence to enable their inclusion in the models of carbon cycling. Actions should assess and model the as yet poorly quantified carbonate-forming invertebrate species in the deep sea, such as reef-building scleractinians, as well as their resilience to cumulative impacts of global changes. Actions should contribute to ocean observations and the Digital twin of the oceans by providing an ocean carbon-modelling environment. Actions should improve the sampling of regions and metrics for marine organisms and should gather evidence and data to estimate and quantify the global CO2 sequestration potential of protecting and restoring populations of invertebrates and vertebrates to previous levels.

The importance of polar regions in the carbon cycle needs to be kept in mind. Among the stressors, the effects of trawling, drilling, overfishing, deep-sea mining and dredging on carbon cycling and sediment dynamics should be included and investigated using marine monitoring techniques. Actions should link science on the changing ocean physics and chemistry, and more generally on climate, with the study of the marine biota and their evolution.

All in-situ data collected through actions funded from this call should follow INSPIRE principles and be available through open access repositories supported by the European Commission (Copernicus, GEOSS, and EMODnet).