In the article published by IEEE Spectrum, researchers from Monterey Bay Aquarium Research Institute (MBARI) describe how a network of “biogeochemical” profiling floats, part of the Global Ocean Biogeochemistry Array (GO-BGC) and the larger Argo program, is shedding light on underwater carbon cycles and how the ocean responds to marine heatwaves.
These cylindrical floats, built to withstand deep-ocean pressure, drift and dive to depths of around 2,000 meters, measuring parameters such as oxygen, pH, nitrate, chlorophyll, temperature, conductivity, and depth. With over 330 floats deployed by MBARI and more than 4,000 worldwide in the Argo network, this autonomous fleet provides continuous data independent of ship-based surveys.
The data reveal that the ocean’s ability to sequester carbon is more vulnerable than thought. For example, in the Gulf of Alaska following major marine heatwaves (“The Blob” and its successor event), the floats showed changes in plankton structure and carbon export depth: carbon was not sinking as deeply, which means it may return to the atmosphere rather than being stored long-term.
The engineering behind the floats is noteworthy. Each cycle involves descending to about 1,000 meters for roughly 10 days of drifting, then the float dives further to ~2,000 meters before rising again to surface and transmit its collected data via satellite. The cycle is repeatable many times over a lifespan of up to seven years.
While satellites capture surface phenomena and ships perform detailed surveys, these floats operate year-round, through storms, winter, and remote regions, offering a persistent “vital-signs” view of the ocean’s metabolism.
This robotics-enabled measurement system is providing a finer and continuous view of how climate stressors alter ocean processes. For engineers and climate scientists alike, it highlights how layered sensing systems (surface, ship, float) work together and how underwater platforms can drive new insights into the Earth’s carbon system.