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Find Carbon Dioxide Sponge Amidst Volcanic Rubble in the South Atlantic
By Madisen Kim;
The Lawrenceville School, NJ
The carbon cycle, or the processes in which carbon is cycled through different carbon reservoirs, originated when Earth did, regulating atmospheric temperatures, sustaining ecosystems and plants, and providing the backbone of all living things by building DNA and proteins. Yet today, an excess of atmospheric carbon dioxide poses many threats to the earth and leads many to fear for its health.
Carbon dioxide, a greenhouse gas that once naturally and steadily cycled from living things to the environment, has been emitted into the atmosphere at a significantly faster rate and is being stored less and less in underground carbon reservoirs, leading to increased atmospheric carbon dioxide levels and accelerated climate change.
The carbon cycle is split into two parts: the slow carbon cycle and the fast carbon cycle. The slow carbon cycle comprises long-term processes that can take millions of years, including rock weathering, the accumulation of volcanic activity, and the formation of fossil fuels. These processes trap carbon in subterranean reservoirs for millennia, in contrast to the days or months that plants store carbon through the rapid carbon cycle via processes such as photosynthesis and cellular respiration. As humans extract fossil fuels like oil and coal from depths of several kilometers, sequestered carbon interacts with oxygen, releasing more carbon dioxide into the atmosphere.
Although human-led processes, like oil and natural gas extraction, have decreased stored carbon in the long-term carbon cycle, scientists have recently discovered hopeful news about long-term carbon reservoirs. For a long time, scientists have known that eroded underwater mountains produce large volumes of volcanic rubble, commonly referred to as breccia. This year, however, scientists have discovered that breccia can capture dissolved carbon dioxide in the ocean.
For years, researchers have examined how cooled fragments of lava and volcanic rock drilled from deep below the South Atlantic accumulate, trapping carbon. Recently, researchers from the University of Southampton conducted an experiment in which, by drilling below the South Atlantic, they were able to recover the first cores of 60-million-year-old rock samples. These rock cores are part of volcanic rock that has spent tens of millions of years rafting across the seafloor as tectonic plates spread apart. Researchers learned that as seawater flows through these porous, permeable deposits, calcium carbonate condenses and cements the breccia, allowing the rock to store large volumes of dissolved oceanic carbon dioxide. In the South Atlantic specifically, scientists found that the lava rubble there contains between two and forty times more dissolved carbon dioxide than previous samples. Scientists now understand that breccia is a carbon reservoir that has substantial carbon-holding ability and unveils its subsequent ability to regulate atmospheric carbon.
In the past, humans have more commonly drilled breccia in search of uranium, gold, silver, and sulfide. Fortunately, scientists have not identified breccia as an easy source of fossil fuels. In contrast to sedimentary rock that can be drilled and extracted for compressed carbon molecules, the carbon in the breccia is permanently mineralized in the calcium carbonate or “carbon cement.”
The discovery of breccia that stores immense quantities of carbon marks a shift in scientists’ previous understanding of the long-term carbon cycle. Researchers now understand a new hidden mechanism: how breccia rock stabilizes global warming and the climate by absorbing large amounts of excess carbon.
Works Cited
Scientists find a massive hidden CO2 sponge beneath the ocean floor. (2025). ScienceDaily.
Carter, E. (2025, November 24). How we discovered a giant geological sponge for carbon in
rocks deep below the seafloor. Research Communities by Springer Nature; Springer Nature.https://communities.springernature.com/posts/how-we-discovered-a-giant-geological-sponge-for-co2-in-rocks-deep-below-the-seafloor
Coggon, R. M., Carter, E. J., Lewis, Evans, A. D., Lowery, C. M., Damon, Kempton, P. D.,
Cooper, M. J., Routledge, C. M., Albers, E., Estep, J., Christeson, G. L., Harris, M., Belgrano, T. M., Sylvan, J. B., Reece, J. S., Estes, E. R., & Williams, T. (2025). A geological carbon cycle sink hosted by ocean crust talus breccias. Nature Geoscience, 18(12), 1279–1286. https://doi.org/10.1038/s41561-025-01839-5
4C Climate Classroom Global Carbon Cycle | Climate-Carbon Interactions in the Current
Century (4C). (2021). 4c-Carbon.eu. https://4c-carbon.eu/latest-news/project-news/4C
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