Untangling the ocean biological carbon pump
They may be microscopic, but their ability to sequester carbon is phenomenal. We are talking phytoplankton – and scientists working on a project funded by ESA are assessing different aspects of the role that these tiny plants play in the ocean carbon cycle to better understand climate processes.
Our oceans play a fundamental role in Earth’s carbon cycle, and therefore in regulating our climate.
Phytoplankton are at the heart of the biological component of the ocean carbon cycle. These tiny marine plants transfer vast amounts of organic carbon from the surface waters to the deep ocean – a process called the ocean biological carbon pump.
Through photosynthesis, phytoplankton absorb carbon in the ocean surface waters and release oxygen. They absorb as much carbon as all the vegetation on land, despite their biomass being several orders of magnitude smaller.
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Phytoplankton maintain this high production by turning over much faster than plants on land – and when they die, they sink down into deeper waters, taking the carbon with them.
Shubha Sathyendranath at Plymouth Marine Laboratory in the UK leads the Biological Pump and Carbon Exchange Processes (BICEP) project – a project funded by ESA’s Science for Society Programme.
Dr Sathyendranath explains, “The role that phytoplankton play in the ocean carbon cycle cannot be overstated. They are tiny, but versatile and dynamic, with a huge collective impact. Through BICEP, we are gaining greater insight into the complexities of the processes involved and their magnitude, and we rely on data from satellites, such as ocean colour data, to do this.”
Oceans cover two-thirds of the planet and given phytoplankton’s rapid life cycle, it is impossible to get a global view of what is going on from field observations alone.
Phytoplankton change the colour of the surface waters, which can be observed by satellites such as the Copernicus Sentinel-2 and Sentinel-3 missions.
Dr Sathyendranath adds, “Using satellite datasets from ESA’s Climate Change Initiative, we have been able to generate satellite-based products of different pools and fluxes of biological carbon in the surface ocean.
“These products include phytoplankton primary production, phytoplankton carbon, particulate organic carbon, dissolved organic carbon, particulate inorganic carbon and export production.”
While these products may sound a little complicated, together they increase the scientific understanding of the ocean biological carbon pump and its processes and interactions with the Earth system. In turn, this helps us better understand the processes controlling our delicate climate.
Taking the project a step even further, these data products have been turned into a ‘data cube’, which is available through the Earth System Data Lab. A data cube is a simple way of organising and viewing data that can help to yield insights into patterns and trends that might not be immediately apparent otherwise.
The BICEP time series currently runs from 1998 to 2020, but it is being extended and kept up-to-date. Datasets are available through the ESA Open Science Catalogue.
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