What is it about?

Microscopic organisms living in the sun-lit surface of the ocean called plankton remove carbon dioxide from the atmosphere during photosynthesis. When these plankton die, their remains rapidly sink down through the "Twilight Zone" of the ocean (200 - 1000m) where the carbon from their bodies is stored away from the atmosphere for 100s to 1000s of years. This process is known as the Biological Pump and stores about 2 times the amount of carbon dioxide that is currently in our atmosphere. Because plankton are sensitive to climate change, this carbon pool is likely to change in size which will impact future atmospheric CO2 concentrations. We set out to understand how this pool of carbon will change in the future in response to climate change by looking at the future model projections made for the latest Intergovernmental Panel on Climate Change report.

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Why is it important?

We provide the first comprehensive assessment of future changes in biologically-driven carbon storage in the ocean. Previous studies suggest carbon storage will decrease in the future as the amount of organic carbon leaving the surface ocean decreases. We show that carbon storage will actually increase, helping to remove atmospheric CO2 from the future atmosphere. This research identifies the crucial importance of the Twilight Zone region of the ocean (100 - 1000m) for driving carbon storage. This part of the ocean is still poorly understood because it is so hard to observe but it is also just starting to come under pressures of environmental change, fishing and deep-sea mining. Understanding how the Twilight Zone controls how much carbon is stored by biology in the ocean means we can figure out how to avoid the worst impacts from human practices like fishing and mining.


Natural solutions to mitigating the increase in atmospheric CO2 and geoengineering often focus on the role of marine biology in storing carbon in the ocean. However, we have been focusing on the wrong part of the Biological Carbon Pump which means we don't know the full impact of these proposals. This article outlines that we need a more comprehensive view of the Pump that needs to integrate knowledge about ocean physics, plankton ecology and marine chemistry. This article came out of a 3-day virtual Hackathon event during the COVID pandemic. All of the authors are early career researchers, including students, who took part to learn new programming skills or understand a new topic whilst working at home and adapting to a strange couple of years!

Dr Jamie Devereux Wilson
University of Bristol

Read the Original

This page is a summary of: The biological carbon pump in CMIP6 models: 21st century trends and uncertainties, Proceedings of the National Academy of Sciences, July 2022, Proceedings of the National Academy of Sciences,
DOI: 10.1073/pnas.2204369119.
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