BGC-Argo Innovations: Advancing Science for High-Seas Solutions

The high seas, which constitute about two-thirds of the ocean, have long been regarded as a shared resource and responsibility for the global community. They offer crucial services such as climate regulation by absorbing heat and carbon dioxide, ensuring food security, providing habitats for diverse species, and supporting rich marine biodiversity. However, increasing anthropogenic pressures and climate change threaten these services. Moreover, some carbon mitigation strategies, such as marine Carbon Dioxide Removal (mCDR) are being proposed without a full assessment of their effectiveness or potential impacts on ecosystems. As a result, the need for robust ocean governance, informed by ocean science and observations, is growing. The BGC-Argo mission, relying on a global fleet of profiling floats measuring five essential oceanic variables (EOVs), has already revolutionized ocean observation by providing real-time data at the global scale from the surface to the deep ocean on vital biogeochemical processes that drive the ocean’s role in carbon storage, climate regulation, and offer insights into ocean health.Alongside the primary mission of BGC-Argo, our team is designing the next generation of these ocean profiling robots, so-called enhanced BGC-Argo floats (eBGC-Argo). These advanced floats are developed to support long-term missions and integrate a range of state-of-the-art sensors for detailed monitoring of surface and mesopelagic plankton ecosystems, as well as improved quantification of carbon exchange between the ocean surface and deeper layers. Key advances include: hyperspectral light measurements for quantifying the ocean color (remote sensing reflectance), aligned with the capabilities of next-generation satellites like PACE, to assess surface phytoplankton composition and abundance; optical sensors that quantify carbon flux at 1000 meters depth, enabling the first carbon export time series of the global ocean; and imagers capable of counting and sizing particles that drive carbon transfer from surface to depth, with AI-based classification of dominant zooplankton groups. After three years of deployment, promising results showcase these innovations. Moving forward, new sensors, such as passive acoustic devices for monitoring meteorological conditions and marine mammals, and active acoustics for studying macroplankton and small mesopelagic fishes, are currently being tested. These technological advances will significantly enhance ecosystem characterization and carbon flux quantification.The expanding diversity of observations and derived metrics or data products provided by multidisciplinary remote platforms, whether operated as regional or global fleets, underscores their potential for fostering science-based governance. Two examples illustrate this potential: (1) A developing eBGC-Argo-based observation system is being deployed in the Central American Thermal Dome, a prime candidate for designation as a high seas marine protected area (MPA) due to its status as a biodiversity hotspot with rich fisheries, mineral resources, and strategic trade routes; (2) The current BGC-Argo system offers significant potential in establishing a baseline for ocean biogeochemical states, enabling reliable future assessments of mCDR impacts, with eBGC-Argo playing a key role in supporting activities related to Monitoring, Reporting, and Verification.